Gas measurement system

The priority of the gas measurement system requires this application to enjoy the priority of the U.S. application 11/368, 832 filed on March 6, 2006 in accordance with 35U.SC §120/365.

TECHNICAL FIELD The present invention relates to a mainstream respiratory gas measurement system with integrated signal processing and improved optical design, and a method of combining the system.

BACKGROUND Respiratory gas measurement systems have gas detection, measurement, processing, communication and display functions. Think of it as either turning or side flow or non-turning or main flow. The turning gas measurement system transports a part of the sampled gas from the sampling point to the gas sensor that measures the gas composition through the sample tube. The measurement point is usually a breathing circuit or a patient flow path. The non-steered or mainstream gas measurement system does not allow gas to leave the breathing circuit or airway, but uses a gas sensor installed on the breathing circuit to measure the gas composition flowing through the breathing circuit.

Conventional mainstream gas measurement systems include gas detection, measurement, and signal processing elements required to convert detection or measurement signals, such as voltage, into values that can be used by the system to determine the detected gas composition, such as transmittance. In a conventional mainstream gas measurement system, the gas sensor is connected to a sample cell placed in the breathing tube. The gas sensor located on the airway adapter provided in the breathing circuit only includes the components required to output signals corresponding to the characteristics of the gas to be detected. Setting the sample cell directly on the breathing tube creates a "clear" waveform that reflects the bias pressure of the gas measured in the airway, such as carbon dioxide or oxygen, in real time. The sample cell, also called a test tube or airway adapter, is located in the breathing gas stream, eliminating the gas sampling and purification required in a sidestream gas measurement system.

For a conventional gas measurement system capable of measuring carbon dioxide, the gas sensor includes a source that emits infrared radiation, which includes the absorption band of carbon dioxide. Emit red in a direction perpendicular to the breathing airflow path

200780000861.8 The outer ray. The carbon dioxide in the sample gas absorbs radiation at some wavelengths and passes other wavelengths. Conventional gas sensors include photodetectors that measure emitted radiation.

For a gas measurement system that can measure oxygen by using luminescence quenching measurement technology, the gas sensor may include an excitation source that excites a photosensitive chemical disposed on or in the substrate and emits visible light rays, and measures the impact of the chemical when exposed to oxygen. Detector that emits radiation. A known relationship such as the stemVolmer relationship can be used to determine the gas concentration from the time response of light emission.

The conventional mainstream host system includes an electronic device that controls the transmitter in the gas sensor and provides a gas measurement function based on the output signal of the detector. The mainstream gas measurement system known in the prior art transmits analog signals along the cable between the host system and the gas sensor, which is usually 6 to 8 feet in length, and is also susceptible to electromagnetic interference (EMI). This is particularly important for the trend toward the requirement to be consistent with the increased levels of electromagnetic immunity in the international medical equipment standards. Examples of this conventional mainstream gas measurement system are shown in U.S. Patent Nos. 4,914,720 issued to Knodle et al. and 5,793,044 issued to Mace et al.

The measurement and signal electronics are located in the host system, and the existing mainstream gas measurement systems are complicated and expensive to connect to the host system. The host system usually includes circuits that perform functions such as: (1) generating time signals; (2) supplying pulsating energy to the solid-state infrared transmitter; (3) measuring and accurately controlling the temperature of the infrared detector; (4) measuring and controlling Airway adapter heater; (5) Signal adjustment including filtering and programmable gain settings; and (6) Prevent accidental damage to the monitor circuit of the infrared transmitter.

In addition, for clinical application, the mainstream system measurement system must be designed to be robust so that it is not affected by the usual mechanical misuse and environmental changes in temperature and humidity. The instrument, or at least the gas measurement system part of the instrument, must be small and light so as not to hinder the movement of the patient or other medical equipment or treatment. In order to achieve the goal of being small and light, the optical part of the gas measurement system must also be designed so that it occupies as little space and as little weight as possible.

Given these known complexities of conventional gas measurement systems, it is desirable to provide a mainstream gas measurement system that is small, lighter, and easier to connect to the host system. It is also expected that the system provides an improved assembly method over known gas measurement systems.

200780000861.8 Summary of the Invention Therefore, the object of the present invention is to provide an optical platform that overcomes the shortcomings of the known luminescence quenching light platform based on gas measurement systems. According to the present invention, this goal is achieved by providing a gas measurement system assembly, which includes a cover suitable for being arranged on the airway adapter and a luminescence quenching gas measuring assembly arranged in the cover. The luminescence quenching gas measurement assembly includes a light source arranged in a first plane, and at least one detector also arranged in the first plane. A filter is provided on the at least one detector to pass the wavelength of the rays quenched by the luminescence and substantially block other wavelengths. A light shield is provided around at least a part of the light source. This structure provides a relatively compact structure of the luminescence quenching gas measurement assembly.

Considering the following description and appended claims with reference to the accompanying drawings will make it clearer these and other objectives, properties and features of the present invention, as well as the method of operation and the functions and component combinations and manufacturing costs of the related structural elements, all of these drawings form this One part, in which the same reference numerals in the various drawings refer to corresponding parts. However, it can be clearly understood that the drawings are only used for description and explanation, and not used to define the limitations of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a gas measurement system according to the principles of the present invention, which is connected to a host system and configured to be detachably fixed to an airway adapter assembled with a patient's breathing circuit element; FIG. 2 is A perspective view of a gas measurement system configured to be connected to a host system; FIG. 3 is a perspective view of a gas measurement system configured to be detachably fixed to an airway adapter; FIG. 4 is a gas measurement system with a cover shown and an electro-optical assembly of the gas measurement system An exploded view of the gas measurement system; Figure 5 is an exploded view of the electro-optical components of the gas measurement system; Figure 6 is an exploded view of the gas measurement system with the illustrated cover, electronic circuit board, and optical components of the gas measurement system; Figure 7 It is an exploded view of the optical assembly of the gas measurement system with the structural basic unit, the detector assembly and the source assembly shown; Figure 8 is an exploded view of the detector assembly; Figures 9 and 10 are parts of the photomask assembly of the detector assembly Exploded view

200780000861.8 Fig. 11 is a cross-sectional view of the combined mask assembly; Fig. 12 is an exploded view of the source assembly; Fig. 13 is an exploded view of the emitter cover of the source assembly; Fig. 14 is a combined gas measurement along the line 14-14 in Fig. 4 A cross-sectional perspective view of the system; Figure 15 is a flattened view of the combined components of the gas measurement system before being placed in the cover; Figure 16 is the ray tracing of the optical path in the gas measurement system according to the principles of the present invention; Figure 17 is according to the present invention Principle gas measurement system structure diagram; Figure 18 is a schematic diagram of a four-channel optical system in a simple linear structure of the detector assembly optical component according to the principles of the present invention; Figure 19 is a diagram showing a splitter wavelength relative to the filter wavelength Diagrams of embodiments; Figure 20 is a schematic diagram of a four-channel optical system in a zigzag structure; Figure 21 is a schematic diagram of a four-channel optical system in a square array structure; Figure 22 is a schematic diagram of a four-channel optical system in a linear system with a lens structure; Fig. 23 is a schematic diagram of a four-channel optical system in a zigzag structure with a lens structure; Fig. 24 is a schematic diagram of a four-channel optical system in a dogleg structure; Fig. 25 is a schematic diagram of a four-channel optical system in a serpentine structure; 26 is a schematic diagram of a four-channel optical system in a channel structure; FIG. 27 is a side view of an embodiment of a four-channel optical system in a linear structure; FIG. 28 is an exploded view of a part of an optical assembly of a gas measurement system according to the principles of the present invention; and Figure 29 is an exploded view of the luminescence quenching measurement circuit board in the gas measurement system of Figure 28.

DETAILED DESCRIPTION A gas measurement system 100 according to the principles of the present invention includes all signal and data processing, which are required to generate continuous values of partial pressure or gas concentration flowing through an airway adaptor that interacts with the patient The airways are in fluid communication. The gas measurement system is located on the "measuring head" mounted to the airway adapter. The gas measurement system includes the measurement and calculation of the continuous value of infrared absorbing gas such as carbon dioxide and luminescence quenching gas such as oxygen, and the connection of the gas measurement system to the host system.

200780000861.8 The first electronic circuit. In an exemplary embodiment, the gas measurement system 100 collects and processes analog signals, and then transmits digitized patient parameters and waveforms through the interface cable 120 as a series of data streams.

The gas measurement system of the present invention does not require an additional electronic board in the host system that is needed to process the detector output signal, thereby saving space in the host system and reducing the cost of end users. Through design efficiency and miniaturization, the resulting gas measurement system is almost as small and light in weight as existing mainstream gas measurement sensors. The addition of signal processing without significant increase in size or weight is particularly important in applications where the gas measurement system has an airway adapter very close to the patients face at the distal end of the endotracheal tube or nasal cannula to monitor the patients breathing.

Illustrated in FIGS. 1-3 are exemplary embodiments of the airway adapter 40 and the gas measurement system 100 constructed in accordance with the principles of the present invention and adopting the principles of the present invention. The conventional gas measurement system does not set the signal processing and control electronics in the gas measurement system, but sets any of the features in the host system. The present invention utilizes highly integrated digital signal processing (DSP) technology to perform many complex electronic interface functions in a small single-chip processor including program and data storage and analog-to-digital conversion.

Many of the efficiencies obtained in the integrated breathing gas measurement system are the result of repositioning the electronic equipment in the gas measurement system. For example, this repositioning affects the design aspects of the interface cable 120, such as the number of conductors, shielding requirements, and therefore cable thickness, weight, and cost. The cable requires fewer conductors and is therefore smaller, lighter and more flexible, while at the same time placing less load and tension on the sensor. The exemplary embodiment uses 7 wires and one shield, while the conventional device uses 16 wires and two shields.

Compared with conventional gas measurement systems, the present invention has a number of additional advantages, including free/simplified connection to the host system 70, and enhanced immunity to radio frequency interference. With simplified hardware and software interfaces, the host system 70 only requires a simple and small connector to the serial port, and a few power supply voltages. In clinical applications, usually attention is paid to adding weight to the patient's pipeline near the endotracheal tube (ET tube, endotracheal tube), especially for children and neonatal applications. The present invention provides a significant improvement in this regard because the weight and potential delay of the cable can be reduced. The existing cables to the host system are larger in diameter, heavier and less flexible.

Conventional gas measurement systems with components located on or near the patient's airway often struggle to meet the existing 3V/meter immunity standard. Update to the international standard for electromagnetic compatibility of medical equipment

200780000861.8 The first increase to 20V/m. Due to the susceptibility to interference from analog signals transmitted via cables, it will be very difficult and expensive to make these standards meet existing designs. In the present invention, it is not necessary to transmit analog signals to the host system via a cable, and all components and signals that are susceptible to radio frequency interference (RFI) are located near the measuring components in the gas measuring system.

Do not need all the complicated external interface electronic equipment greatly reduces the system cost. The effective use of interconnection technologies such as rigid-flex circuit boards and other manufacturing functions makes the total system cost lower than the cost of existing stand-alone mainstream gas measurement systems.

The measurement and signal processing electronics of the integrated gas measurement system increase the waste heat generated in the gas measurement system 100. The compact nature of the design requires careful consideration of thermal design. For example, the gas measurement system 100 is configured to allow waste heat generated by the transmitter and electronic equipment of the gas measurement system to heat the window of the airway adapter to reduce fog. This feature of the invention allows the removal of ceramic heaters (also called box heaters) used in conventional gas measurement systems. In addition, the elimination of the ceramic heater along with other effects of this design reduces the total power consumption of the present invention from approximately 5 watts (W) to 1.25W.

Figure 1 is a perspective view of a gas measurement system 100 connected to a host system 70 and configured to be detachably secured to an airway adapter 40, which is combined with a patient breathing circuit 20 element. The airway adapter 40 is usually assembled in the breathing tube 20 between the elbow 25 and the "Y" tube 30. The elbow 25 is a connection to the patient interface such as a mask or inner trachea. The "Y" tube 30 is connected. To positive pressure generators such as ventilation equipment. The host system 70 supplies power to the gas measurement system 100, receives the gas concentration signal and the measurement value output from the gas measurement system, and displays the measurement value when the gas concentration signal is a carbon dioxide concentration signal. For example: (a) Carbon dioxide in the patient's breath Concentration, (b) inhaled carbon dioxide, (ο) respiration rate, and (d) end-tidal carbon dioxide. Similarly, where the gas concentration signal is an oxygen concentration signal, the host system 70 displays measured values such as (a) the oxygen concentration in the patient's breath, (b) the inhaled oxygen, (c) the breathing rate, and (d) the tidal air. End oxygen.

As described above, the cable 120 connects the gas measurement system assembly 100 and the host system 70 together. The distal end 110 of the cable 120 is reliably and detachably connected to the host system. The proximal end 123 of the cable 120 includes a strain relief element 130 that allows tension to be applied to the cable 120 without affecting the conductors therein. Power is supplied from the host system to the gas measurement system via the cable. However, the present invention also considers that the gas measurement system can be integrated

200780000861.8 Complete or separate battery pack power supply and wirelessly transmit its data to the host system, thus eliminating the need for cable 120. Consider using protocols known in the prior art such as Bluetooth, Zigbee, and Ultra Wideband (UWB) wireless communications used in body area networks (BAN) and personal area networks (PAN). The gas measurement system can also be connected to a network hub via a cable, which integrates the signal of the gas measurement system with other physiological measurement values of the gas.

The end of the airway adapter 40 (Figures 1 and 3) is designed to connect to the patient interface and the respiratory system. For example, the airway adapter may be provided between the inner trachea (not shown) inserted into the patient's trachea and the breathing circuit of the positive pressure generator or the ventilator 75. In an exemplary embodiment, the gas measurement system 100 is used to measure the patient's carbon dioxide and oxygen levels. The particular airway adapter 40 described in Figures 1 and 3 is not itself part of the invention. Likewise, the present invention contemplates that the gas measurement system of the present invention can be used with any conventional airway adapters, including absorption or luminescence quenching adapters. U.S. Patent Application No. 09/841,451 and U.S. Publication No. 2002/0029003 ("the '451 Application'") issued to Mace et al. disclose adapters suitable for gas measurement through infrared absorption and luminescence quenching. The content is combined and referenced here. The airway adapter 40 is typically molded from polycarbonate or equivalent polymers.

In the exemplary embodiment of the present invention shown in Figures 3 and 14, the airway adapter 40 has a generally parallelepiped central portion 42 and two cylindrical ends 44 and 46, with a sampling channel 47 passing through the adapter from One end to the other. The end portions 44 and 46 and the central portion 42 are axially aligned. The central part 42 provides a seat for the gas measurement system 100. The overall U-shaped box element 48 positively positions the gas measurement system 100 forward on the adapter and along the transverse direction indicated by the arrow 50 in FIGS. 1 and 3. The arrow 50 also shows the direction in which the airway adapter 40 is moved to combine it with the gas measurement system 100. Holes 52, 53, and 54 are formed in the central portion 42 of the airway adapter 40.

Assemble the gas measurement system 100 to the airway adapter, for example, aligning the holes 52 and 54 along the optical path 56 as shown in FIG. 14. The light path 56 extends laterally from the light source assembly or the emitter 400 in the gas measurement system 100 through the airway adapter 40 and one or more gases flowing through the airway adapter. The light path continues to extend from the airway adapter to the detector assembly 300 in the gas measurement system 100. In order to prevent the gas flowing through the airway adapter 40 from escaping through the holes 52 and 54 to unacceptably weaken the infrared rays that cross the optical path 56, and to prevent external materials from entering the airway adapter, the infrared ray transmission window 58 and 60 dense

200780000861.8 Seal the hole. In addition, the hole 53 is covered by a window 49. In physical contact with the window 49 and located inside the airway adapter 40 is a sensitive film with photosensitive chemicals. The chemical emits radiation in response to excitation when the chemical is exposed to a gas such as oxygen. It should be understood that the airway adapter may include one or more holes 52, 53, and 54, and one or more gas measurement techniques using the holes.

4 is an exploded view of the gas measurement system 100 including the polymer cover 210 and the gas measurement system electro-optical component 220. Perhaps the gas measurement system electro-optical assembly 220 best shown in Figures 4 and 7 includes the following elements: (a) infrared radiation source assembly 400 (shown in more detail in Figures 12-13), (b) infrared radiation detection The device assembly 300 (shown in more detail in FIGS. 8-11), and (c) select the luminescence quenching measurement circuit board 235. In the combined gas measurement system, the strain relief element 130 is held in place by the walls 214 and 252 provided on the bottom 250 and the cover 210. When the cover is attached to the base, the wall 214 and the wall 252 cooperate. This can be achieved by using any conventional technique such as an engagement fit or a friction lock structure.

The gas measurement system electro-optical component 220 and the flexible circuit 230, the bracket 232, the luminescence quenching measurement circuit board 235, and the optical component represented by 240 generally including the optical element of the gas measurement system are combined in FIGS. 5-6. together. The light source and detector components in the optical assembly are connected to the "U"-shaped base 250 and mechanically and electrically connected to the flexible circuit board, which is folded around these components and connected to the base 250. This assembly allows the active components of the gas measurement system to be tested to be used as a unit rather than stand-alone before assembly. Therefore, it is not necessary to wait until the gas measurement system is fully assembled to determine whether it meets the performance specifications. The result is a significant reduction in cost, which is also a goal promoted by reducing wiring and significantly reducing assembly costs.

FIG. 5 is an exploded view of the gas measurement system electro-optical component 220 having the flexible circuit 230 separated from the gas measurement system optical component 240, the bracket 232, and the luminescence quenching measurement circuit board 235. The flexible circuit 230 includes rigid board portions 225, 226, 227, and 228 (see FIG. 15). The rigid part is connected to each other by the flexible part. The flexible circuit board includes analog and digital circuits that drive the infrared source and convert the signal of the detector assembly into an output value of an infrared absorbing gas such as carbon dioxide, and/or convert the signal of the luminescence quenching assembly into an output value of a gas such as oxygen. . The circuit board 235 includes circuits and optical elements for detecting oxygen by luminescence quenching technology. The optical assembly 240 includes a detector assembly 300, a light source assembly 400, and a heater flexible circuit 245 for controlling the temperature of the oxygen film. The heater flexible circuit 245 and the gas measuring optical assembly 240 on the top of the "U"-shaped base 250 are combined together. Before welding'

200780000861.8 The needle 246 at the distal end of the heater flexible circuit 245 is inserted into the corresponding hole 237 in the end of the luminescence quenching measurement circuit board 235. Similarly, the needle 381 of the detector flexible jumper 380 is inserted into the corresponding hole 231 along the edge of the board portion 226 of the flexible circuit 230.

6 is an exploded view of the gas measurement system 100 showing the cover, the electronic circuit board, and the optical components of the gas measurement system. The gas measurement system electro-optical assembly 220 having the flexible circuit 230, the bracket 232, and the circuit board 235 is shown as being separated from the gas measurement system optical assembly 240.

FIG. 7 is an exploded view of the gas measurement system optical assembly 240 showing the structural base element 250, the detector assembly 300, and the source assembly 400. As shown in FIG. The base element 250 of the gas measurement system 100 supports the source assembly 400 in the source assembly chamber 253 and supports the detector assembly 300 in the detector assembly chamber 254. A generally rectangular gap 66 is provided between the chambers 253 and 254 brackets. The gap 66 is provided to engage the central portion 42 of the airway adapter 40. The two pairs of complementary cavities in the first end 258 and the second end 257, mostly defined by the side walls and edges of the base member 250, cooperate to define the infrared radiation source chamber 253 and the infrared radiation detector chamber 254, respectively. The gas measurement system base element 250 can be molded from polycarbonate or any other suitable polymer. In the exemplary embodiment described, the base element 250 has a flat side wall and an integrated edge perpendicular to the side wall.

A source hole 256 is defined in the cover wall to provide an optical path for the radiation generated by the source assembly 400 to enter the cell portion of the airway adapter. A source hole 255 is defined in the cover wall to provide an optical path for the radiation passing through the existing airway adapter to reach the detector assembly 300. In the described embodiment, a luminescence quenching hole 260 corresponding to the hole 53 is also provided in the cover to measure the luminescence of the material quenched by oxygen in the sample gas. It will be understood that the luminescence quenching feature and the absorption feature of the present invention can be used alone or in combination. Therefore, depending on the use of one or two of these gas measurement techniques, the holes 255, 256, and 260 can be eliminated.

FIG. 8 is an exploded view of the detector assembly 300 of the gas measurement system 100, and FIG. 9 is an exploded view of the detector optical assembly 350. The detector assembly 300 includes detectors 340 and 345 arranged on a heat sink 330, a heat sink spacer 320, and a detector assembly circuit board 310. The heat sink 330 is connected to the heat sink spacer 320, and the heat sink 320 is connected to the detector assembly circuit board 310. The resulting support assembly 325 is assembled to the detector optical assembly 350 by aligning the holes 335, 336, and 337 in the light block 370 and the corresponding positioning pins in the heat sink 330. The detector optical assembly 350 includes optical elements such as lenses

200780000861.8 No.

364, filters 356 and 358, mirror 354 and beam splitter 352, and are combined with detector support assembly 325.

Provided in the groove of the heat sink 330 are the data and reference detectors 340 and 345 aligned in the same plane (ie, coplanar), thereby allowing the detector to be temperature-regulated more effectively. Since lead selenide has sensitivity to infrared radiation including the wavelength of interest, it is preferable to manufacture the detector with lead selenide detector elements. In addition, the lead selenide data and reference electrodes 340 and 345 are very sensitive to temperature. Therefore it is important to maintain the two detectors at the same temperature, preferably not exceeding a tolerance of 0.02°C. The detector heating system maintains the detectors 340 and 345 at the selected operating temperature. The detector heating system includes detector heating elements 391 and 392, a temperature control thermistor (not shown), and the detector assembly circuit board 310 and Operation/control circuit (not shown) in the flexible circuit 230.

The detectors 340 and 345 are connected to the detector assembly circuit board 310, and a bias voltage is applied to the circuit board 310 across the infrared radiation detection element portion of the detector of the same configuration and size. The gap between the detector and the boundary of the groove accommodating the detector in the thermostatic support is used to electrically insulate the detector from the conductive and thermostatic support. The thermal resistor (not shown) is set so that its center is located in the groove 322 of the fin spacer 320. The heating elements 391 and 392 are located at the ends of the diffuser 330 and are in close contact with the heat sink. The heating elements 391 and 392 include a flexible circuit portion having a remote surface set resistance for transferring heat.

Two pins 388 and 389 are provided in the heating element to connect them to the detector assembly circuit board 310. The flexible circuit portions of the heating elements 391 and 392 are in close contact with the heat sink 330. In an exemplary embodiment, an epoxy resin preferably having high thermal conductivity is used to bond the flexible circuit portion of each heating element to the heat sink 330. The needles 388 and 389 of the heating elements 391 and 392 are inserted into the corresponding holes 386 and 387 on the circuit board 310 of the detector assembly. The detector flexible jumper 380 connects the detector assembly circuit board 310 to the board portion 226 of the flexible circuit 230 through an interface. The needle 382 of the detector flexible jumper 380 is inserted into the corresponding hole 383 along the edge of the circuit board 310 of the detector assembly. The needle 381 of the flexible jumper 380 of the detector is inserted into the hole 231 of the board portion of the flexible circuit 230.

The detector optical assembly 350 will be described with reference to FIGS. 9-11. The detector optical assembly 350 includes a beam splitter 352, a mirror 354, filters 356 and 358, and a detector lens 364. The beam splitter is generally a parallelepiped structure. The element is made from a material such as silicon or sapphire, which is basically sensitive to the wavelength of interest

200780000861.8 The first electromagnetic energy is transparent. The exposed front surface of the beam splitter is completely covered with a coating that can reflect electromagnetic energy that strikes the beam splitter and has a wavelength longer than the selected value. In the described embodiment of the invention, the coating will reflect energy with wavelengths greater than about 4 microns to the data filter 356 and the data detector 340. On the contrary, energy of a shorter wavelength is emitted to the mirror 354 and the reference filter 358 and the reference detector 272 through the beam splitter 352.

The beam splitter 352 is glued to the frame-shaped protrusion 351 formed integrally with the light block 370 by epoxy resin or in other ways to fix the beam splitter 352 in a suitable place. Precisely determining that the beam splitter 352 is located in the optical block 370 has the advantage that there is no need to adjust the direction of the beam splitter subsequently. Similarly, the mirror is glued to the frame-shaped protrusion 353 by epoxy resin or in other ways to fix the mirror 354 in a suitable place, and the protrusion and the light block 370 are integrated. Moreover, the electro-optical assembly of the present invention has an optimal focal length, which makes it possible to use a smaller and less expensive detector assembly of a gas detection system.

The band pass filters 356 and 358 define the infrared radiation energy that is reflected from the beam splitter 352 and the beam splitter 352 which emits and strikes the data and reference detectors 340 and 345 to reach the energy in the selected bandwidth, respectively. In the exemplary embodiments and applications of the invention discussed and described in the drawings, the reference detector filter 358 is nominally centered at a wavelength of 3.7 microns. Such a filter emits the maximum energy in the vicinity of the carbon dioxide band absorbed by the data detector 340. The maximum energy absorption in the adjacent bandwidth is selected so that the output of the reference detector 345 will be at least as large as the output of the data detector 340. This is obviously beneficial to improve the accuracy of the gas concentration representation signal obtained by subsequently determining the ratio of the data to the reference signal.

The data detector bandpass filter 356 is nominally centered at a wavelength of 4.26 microns. The carbon dioxide absorption curve is very narrow and strong, and the band pass filter 356 is centered on the emission band within the absorption curve. Therefore, if there is a change in the level of carbon dioxide in one or more of the gases analyzed, the maximum modulus of the specified change in the level of carbon dioxide can be obtained. The data and reference band pass filters 356 and 358 are glued into the grooves 360 and 362 of the light block 370. When the light block 370 is connected to the detector circuit board, the data and reference bandpass filters 356 and 358 are aligned with the data and reference detectors 340 and 345, respectively.

All the energy of the infrared ray beam propagating along the optical path 56 and reaching the detector assembly 300 with a wavelength greater than the selected interception and at the same interval is reflected to the data detector 340. Similarly, the energy of the shorter wavelength is transmitted to the reference detector 345 through the beam splitter 286. Because of this, the aforementioned detector 340

200780000861.8 The physical relationship between No. 345 and No. 345, and the size and structure of the energy interception detection elements of those detectors, both detectors "see" the same image of the electromagnetic energy beam. This significantly improves the accuracy of the detector assembly 300.

In other words, optically, the data and reference detectors 340 and 345 that are accurately positioned relative to each other and the beam splitter 352 is arranged in the above-described manner, these elements operate as if two detectors are precisely stacked on top of each other. Therefore, the electromagnetic energy of the beam reaches the two detectors in the same spatial pattern. By optically making the two detectors 340 and 345 spatially consistent, and simultaneously electronically sampling the detector output, the ratio of the subsequent data and the reference detector output signal can also be used to effectively eliminate the interference attributable to the above-mentioned gas. The accuracy of the foreign material collected by any of the lane adapter optical windows 58 and 60, the window 460 of the source assembly, or the window 364 of the detector assembly 300 described below is adversely affected.

The electromagnetic energy in the light beam propagating along the optical path 56 reaches the beam splitter 352 through the hole 366 defined in the front wall 339 of the light block 370. An infrared ray transparent lens 364 usually made of sapphire crosses the hole 366 and prevents carbon dioxide and other foreign materials from entering the light block 370. The lens 364 is bonded to the light block in any convenient and suitable manner.

The infrared ray source assembly 400 will now be described with reference to FIGS. 12 and 13. The infrared ray source assembly 400 emits infrared rays in the form of a light beam 480 (see FIGS. 14 and 16) propagating along the optical path 56. The infrared ray source assembly includes an infrared ray emitter 445, converters/lead frames 446 and 447 arranged in the light source ring assembly 420, and a lens 460 arranged in a lens holder 440 connected to the light source ring assembly 420. The infrared ray emitter 445 includes a substrate formed of a material with low thermal conductivity. This is important because it significantly reduces the energy required to heat the transmitter to operating temperature. When a current is applied to the emission layer 448 of the emitter 445, the emission layer and the substrate are heated, and the substrate grows or increases in length due to thermal expansion, and the growth is adapted by the elastic adhesive instead of limiting. Therefore, the stress that will be applied to the transmitter if the two ends are strictly fixed is avoided, which eliminates possible damage to the transmitter or complete failure of the component if high mechanical strain is applied.

The emitter 445 energizes the emitter 445 of the light source assembly 400 to heat it to a certain operating temperature, at which temperature it emits infrared rays in a suitable bandwidth range by influencing the current from a suitable power source through the emitting layer 448. The power supply is connected to the emitter layer 44 via conductive leads 451 and 452 & the lead is soldered

200780000861.8 First or otherwise physically and electrically connected to the opposite ends of the adapters 446 and 447.

The adapters 446 and 447 are installed in the source ring 420 of the source assembly 400. Due to the heating of the emission layer 448 of the infrared ray emitter 445, the environment in which the element operates can reach an increased temperature. Therefore, the source ring is made of a polymer whose structure is stable at the temperature reached by the infrared ray emitter 445 when it is operating. In the described exemplary embodiment, the source ring 420 has a cylindrical structure including an integrated wall 454 and a bottom 453. Protruding from the bottom 453 in the same direction are component setting bosses or protrusions 456, 457, 458, and 459. Spaced apart protrusions 456 and 457 and supplementary spaced apart protrusions 458 and 459 surround opposite sides of the adapters 446 and 447. The bosses or protrusions 461 and 462 separate the adapter parts while providing a gap therebetween to electrically insulate the two adapter parts. This is necessary so that a voltage can be generated on the transmitter 445 to allow the operating current to flow through the transmitter.

Referring now to FIGS. 14-16 and FIGS. 12 and 13, the infrared rays output by the infrared ray emitter 445 emission layer 448 are focused and propagated along the optical path 56 through the lens 430 disposed in the lens holder 440. The outer material is separated from the inside of the infrared ray source assembly 400 by a sapphire or other infrared ray transmission window 460 that spans and closes the hole in which the lens 430 is disposed. The window 460 is joined or otherwise adhered to a frame-like protrusion or groove 442 formed in the lens holder 440 of the infrared ray source assembly 400.

The gas of interest (usually carbon dioxide) flowing through the airway adapter absorbs the energy that can be carried to a degree commensurate with the concentration of the gas. Thereafter, the attenuated infrared ray beam passes through the hole 306 in the front wall 308 of the detector portion of the cover 210, is intercepted by the beam splitter 352, and is reflected to the data detector 340 or is transmitted to the reference detector 345 after being reflected by the mirror 354. The bandpass filters 356 and 358 in front of those detectors limit the energy reaching them to a specific (and different) energy band. Each of the detectors 340 and 345 outputs an electrical signal whose magnitude is commensurate with the intensity of the energy striking the detector. The signal is amplified by the electronic circuit on the detector system circuit board 310, and the signal is transmitted to the digital signal processor on the board portion 225 of the flexible circuit 230. The processor usually determines the signal ratio of the detector to generate a third signal that accurately reflects the gas concentration being monitored.

The light path 56 is shown, which is traversed by infrared rays between the windows 58 and 60 provided in the holes 52 and 54 respectively, and is located within the overall "U"-shaped box element 48 of the airway adapter 40. easy

200780000861.8 The optical alignment feature of the bottom 250 is clear from the cross-sectional view. The feature of the lens holder 440 attached to the source ring assembly 420 is used to properly align the source assembly 400 in the bottom 250. Similarly, the features of the detector optical assembly 350 are used to properly align the detector assembly 300 in the bottom 250.

The luminescence quenching optical system 236 is assembled to the luminescence quenching measurement circuit board 235. The luminescence quenching measurement circuit board 235 includes a circuit that drives the excitation source 243 and measures the response of the detectors 238 and 239 using a detection technique based on amplitude or phase. An exemplary luminescence quenching optical system 236 includes an excitation source 243 and detectors 238 and 239 on each side of the excitation source 243 (see FIG. 29).

Figure 15 is a flattened view of the gas measurement system assembly before being placed in the cover. Before assembling the detector assembly 300 and the source assembly 400 to the "U" shaped bottom 250, these components are physically and electrically connected to the flexible circuit 230. The detector assembly 300 is connected to the board of the flexible circuit 230 with the detector flexible jumper 380 226 (See Figures 5 and 8). The ends of the lead wires 443 and 444 (FIG. 12) of the source assembly 400 and the connector of the cable 120 are connected to the board portion 227 of the flexible circuit 230. To combine the flattened electro-optic assembly 222 to the bottom 250, the source assembly 400 and the detector assembly are connected to the bottom 250. The board portion 225 of the flexible circuit 230 is placed on the top of the "U" shape of the bottom 250. The plate part 228 is folded to fit the detector assembly chamber 254, and the plate part 227 is folded to fit the source assembly chamber 253.

Figure 16 shows the ray trajectory of the optical path in the combined gas measurement system. The ray 480 in FIG. 16 is only descriptive and is represented as a point source as the emitting layer of the emitter 445. The infrared rays from the emitter 445 are aligned by the hemispherical lens 430. The shape of the airway side of the lens is used to "converge" the rays into parallel lines. The ray strikes the infrared absorbing gas and substance that is absorbed and scattered in the airway adapter. The remaining rays pass through the window of the airway adapter and enter the detector assembly 300. The ray passes through the lens 364 and is collimated/focused on the beam splitter 352, where nearly half of the ray is reflected and passed through the filter 356 and the detector 340, while the other half is transmitted and reflected by the mirror 354 to the filter 358 and pointing detector 345.

FIG. 17 is a structural diagram of a gas measurement system 500 according to the principles of the present invention. The microprocessor 510 provides the control, measurement, and signal processing functions of the present invention. An exemplary processor is TMS320F2812 DSP manufactured by Texas Instruments. The microprocessor 510 provides a source time signal to the source component 400, which is driven by a 5.0 VDC pulse voltage in a unipolar mode. The source emitter monitor 511 monitors the source pulse width and maintains it within an allowable window. The system is used to reset the generator 520 during the power-up sequence so that

200780000861.8 The processor resets the processor only when the stable voltage is reached and during the power-down sequence so that an orderly power-down sequence will occur.

An executable program that can be stored in an electrically erasable programmable read-only memory (EEPROM) 530 or elsewhere is transferred to the microprocessor 510. The data from the detector assembly 300 and the reference channel signal are amplified by the digital attenuation 540 before the analog-to-digital conversion in the microprocessor 510. The microprocessor 510 controls the detector heater 590 located in the detector assembly 300 through a feedback loop. The low-level signal of the detector is AC coupled, amplified and level converted to collect the signal completely. Double sampling and keeping the platform in the ADC allow simultaneous sampling of the data and reference channels. Active gain and offset adjustments compensate for the optical and electronic variables in the signal chain. The detector heater driver controls to send energy to the detector while the detector thermal resistance driver provides thermal resistance signals to the processor. Control algorithms such as PID controllers are used to adjust the temperature, which is usually between 40°C and 50°C, to within ±0.02°C. The detector heater is powered by the +5V DC power supply, which is also used to power the analog circuit regulator. The window heater 245 includes a temperature detection element and a heating element. The electronic equipment on the circuit board 235 and the microprocessor control the transmission of energy to the heating element. The control algorithm in the microprocessor 510 that detects the temperature maintains the temperature of the heating element at a temperature much higher than the ambient temperature in the airway adapter. CODEC 555 has an integrated digital-to-analog converter and analog-to-digital converter Decoders and encoders. The CODEC 555 connected to the microprocessor 510 uses the outputs of the detectors 238 and 239 to modulate the excitation source 243 in a way of performing phase-based lifetime measurement. The serial driver 570 uses transmission and reception lines denoted by Tx and Rx for bidirectional communication. To provide signal return and digital-to-analog grounding, the power supply 560 receives power from the VSRS and VA lines.

The above-described exemplary embodiment of the present invention shows an optical assembly of an infrared detector system having a linear configuration, which includes a single beam splitter, a single mirror, two filters, and two detectors. This configuration is very suitable for detecting a single gas flowing through the sample chamber. However, the need to measure additional gas with a transducer of the same size as the transducer used for single-gas measurement is increasing. To this end, the present invention considers other embodiments of a gas measurement system including an infrared spectrometer portion capable of measuring a variety of gases. For example, a four-channel system will allow the concentration of carbon dioxide, nitrous oxide, and certain anesthetics to be quantified along with a reference channel. The present invention is also suitable as an effective non-dispersive infrared multi-channel gas analysis configuration using one or more of the following novel features and combinations:

200780000861.8 No.

a) Divide the spectrum into multiple two-color beam splitters in a binary sequence, and select a specific wavelength with a narrow band pass filter;

b) Combine two or more two-color separators on a single substrate

c) Among them, all the detectors are set on a single plane and the geometric configuration of a multi-channel single turning mirror can be used;

d) Broadband bandpass filter instead of two two-color splitters;

e) Ring focusing lens, and combined sapphire or wrong lens; and/or

f) The lenses located on both sides of the beam splitter element compactly provide independent control of reflected and transmitted light. * Fig. 18 is a schematic diagram of an exemplary embodiment of an optical system arranged in a linear structure according to the principles of the present invention. The optical system in this embodiment is composed of four channels, and each channel has a narrow band pass filter and a detector. Each filter/detector assembly 611, 612, 613, and 614 uses similar detectors, but each filter has a different band pass. After passing through the sample chamber, the beam of the infrared source enters the optical system. The light beam is indicated by reference numeral 600 in the drawing. The light beam 600 strikes the first dichroic beam splitter 601. The first dichroic beam splitter 601 may be configured to pass the shortest wavelength of interest or to pass the longest wavelength of interest. All other wavelengths will be reflected. The second and third dichroic beam splitters 602 and 603 sequentially split other wavelengths or channels from the reflected beam. The order of the splitters is somewhat arbitrary. The final element, the plane mirror 604, reflects the final channel to the filter/detector assembly 614. The use of this mirror allows all the detectors to be in the same plane (ie, coplanar).

Figure 19 depicts the filter characteristics of the short (low) bandpass splitters 605, 606, and 607 as a function of wavelength, relative to the filters of the bandpass filters 615, 616, 617, and 618 of each channel of the linear system of Figure 19 feature. Each detector has a narrow-band filter to select the wavelength required for detection, with more features than can be accomplished with a two-color beam splitter. Note that this logic can be reversed, meaning that the first optical splitter can pass the longest wavelength 618 and reflect other wavelengths to the filters 615, 616, and 617. Then, the following optical splitter can be short-pass, in which the order will be 617, 616, and 615, or it can be long-pass, in which the order is 615, 616, and 617.

Alternatively, the long band pass and the short band pass can be mixed in a certain order. Note that the dual-color splitter is used instead of

200780000861.8 A more conventional broadband splitter is used to substantially improve the amount of signal energy that will reach the detector, especially the final detector. The linear system has the advantage of simple design, and all the detectors are on the same plane. However, the beam basically extends along the path length to the last detector, so the energy collected by the last detector is less than the previous detector.

Fig. 20 is a schematic diagram of an optical system having a zigzag structure. This system takes advantage of the fact that the dielectric bandpass filter will reflect all non-transmitted wavelengths. In essence, there is conservation of energy. In terms of the zigzag shape, the first element is the mirror 621. Each of the splitters 626, 627, 628, and 629 is a narrow band pass filter. Not all energy selected from a particular channel is reflected to other channels, so the order of filter/detector components 622, 623, 624, and 625 is arbitrary. Note that each filter must be designed to operate at the selected angle (usually 40° to 45°). Because the narrow band pass filter performs the dual function of ordering channels and narrowly limiting the desired wavelength, the system has a shorter path length and a smaller number of parts. The detector is now on two planes, but the detector components are the same. The system shown shows the optical path from the light source to the final detector on the same plane. To facilitate packaging, the components behind the mirror 621 can be rotated 90 degrees around the optical axis, so that the optical axis of the light source is perpendicular to the plane of the glyph.

Fig. 21 is a schematic diagram of an optical system having a square array structure. A two-color beam splitter is used in a more straightforward binary selection process. For example, using the characteristics of the filter and beam splitter shown in FIG. 21, the first beam splitter 631 can be set at 4 microns to split the spectrum of interest in half. The reflected half is separated again at 4.4 microns, and the reflected part directly reaches the narrow band pass filter/detector assembly 632, and then the passed part is reflected at the mirror 636 to the narrow band pass filter/detector assembly 633. The mirror 638 reflects the half passed by the beam splitter 631 to the beam splitter 637 set to 3.45 microns. As in the first described leg, the beam splitter 637 splits the beam and directs the beam to the narrow bandpass filter/detector assembly 634 and 635θ respectively. The mirror 636 and the beam splitter 631 rotate the beam channels 1 and 2 around the optical axis and The path of channels 3 and 4. Through the "rotating leg" device, all the detectors can be set very close on the same plane. In addition, in this system, two mirrors shown as mirrors 636 can be manufactured as a single piece, and a beam splitter shown as beam splitter 637 can also be formed on a single substrate.

It should be noted that the combined beam splitter can be constructed as a pair of overlapping two-color beam splitters, one on each side of the sapphire substrate, or it can be constructed as a broadband pass filter, where the band edge forms a wavelength division function

200780000861.8 Number. The system described below may be similar in overall structure, but it includes focusing elements in the form of sapphire lenses, concave spherical mirrors, or non-concave spherical mirrors.

The advantage of adding a focusing element to the system is that the energy collection efficiency is greatly improved on each detector. Without the focusing element, the light beam emitted by the light source will be much larger than the detector on the plane of the detector. The oversize is due to two reasons: system enlargement, and deformation. The ratio of the numerical aperture of the light source to the numerical aperture on the detector is the magnification. The numerical aperture is the sine of the half-angle time of the refractive index beam (in this embodiment, 1). Depending on where the focus is set, the magnification is from 5 to 7. The diameter of the light source is approximately 0.02", so the image on the detector plane will be in the range of 0.16" to 0.2". But the detector diameter is usually 0.08 (it is possible to use larger detectors, but the cost increases rapidly with size). In addition, although the source lens produces a very good image in the center of the field, the points on the source edge are deformed, which increases the magnification of the basic image. However, if the positive focusing element can be placed near the detector, the magnification can be reduced radially, and the deformation can also be reduced in an absolute sense. In the example system, compressing the beam can improve the detection efficiency by a factor of four or more. Note that taking into account the deformation of the beam, it is not feasible to make a simple lens form a good image on the detector, but in fact, because the goal is only to collect as many infrared rays as possible, a good image is not required.

Fig. 22 is a schematic diagram of an optical system having a linear system configuration including a lens in an optical assembly. This configuration is similar in layout to the linear configuration of FIG. 18, with the addition of a lens 645 inserted along the optical path, usually located between the beam splitters 642 and 643 and the filter/detector assemblies 652 and 653. The function of the lens is to compress the beam energy to the detector assembly 653 and the detector assembly 654, which will improve the detection efficiency in these channels. The function of the lens is to reduce the magnification of the system. In addition, lenses 655-658 can be added to each channel, further reducing the magnification, and improving and balancing the efficiency of all detectors.

FIG. 23 is a schematic diagram of an optical system having a zigzag configuration in which a lens is included in the optical assembly again. In this configuration, which is essentially a modification of the configuration shown in Figure 20, a lens is added to each channel to compress the beam size. If a single lens is added between the beam splitter and the detector, only the transmitted beam will be affected, and the reflected beam will be magnified more than expected in the final channel. But if a single lens is added in front of a beam splitter that is strong enough to compress the beam suitable for the detector, it will be reversed.

200780000861.8 The influence of the first beam will be doubled and will be too strong.

The present invention solves this problem by dividing the lens into two elements with one part on either side of the narrow band pass filter. For example, the split lens/filter assembly 669 includes lenses 666 and 668 and a filter 667. By dividing the lens on each channel in this way, the transmitted part and the reflected part each receive the effect of the full lens. Optionally, the two lenses on each channel can be different, so that, for example, the transmitted beam is more compressed than the reflected beam. Note that the use of this system eliminates the two-color beam splitter.

Fig. 24 is a schematic diagram of an optical system having a bent structure. The structure is similar to the square array in that the two-color beam splitter is used to split the beam by wavelength in a binary manner. The two-color beam splitter 682 performs the first division. The reflected beam reaches the reflector 68L. This is one of the four focusing mirrors added to compress the beam to improve detection efficiency. These mirrors may be spherical, but preferably they are non-spherical. Because a spherical element with a high angle of incidence will produce two different focal points, one in the plane of incidence and the other perpendicular to the plane of incidence, the above-mentioned preference is produced. In other words, such a mirror will produce astigmatism. By making the radii of curvature on the two axes different, astigmatism can be corrected. Aspheric is the general term for non-spherical surfaces. The mirror shown here is a ring, a subset of the general category. In this case, even if a good image is not required, the non-spherical mirror can produce a more uniform circular beam pattern.

The reflected and refocused light beam is split again at the dichroic beam splitter 675. Again, the reflected light beam is refocused onto the band pass filter/detector assembly 672. The transmitted light beam reaches the filter/detector assembly 671. The light beam transmitted from the beam splitter 682 is refocused by the focusing lens 683 and divided by the beam splitter 678 again. Like the other two channels, the light beam reaches the filter/detector assembly 674 or passes through the focusing lens 677 to the filter/detector assembly 673. Note that this system provides high collection efficiency and a compact single-plane detector array.

Fig. 25 is a schematic diagram of an optical system having a serpentine structure. The "snake" structure is similar to a linear array, except that focusing mirrors 691-694 are added to each channel. The first division is performed by the two-color beam splitter 681, followed by the beam splitters 682 and 683 and the mirror 684. Focusing mirror may be spherical, but the collection efficiency of the non-spherical mirror rate greatly improved. In an exemplary embodiment of the present invention, the mirror is constructed in a single long mode. Filter/detector components 685, 686, 687, and 688 consist of narrow band pass filters and detectors, and other front

200780000861. 8 The first described embodiment is the same.

Fig. 26 is a schematic diagram of an optical system having a channel structure. Infrared energy can be distributed to the planar array of detectors in different ways. The energy of the source 698 can be directed to the tube 696 by the mirror 699, or can become an optical channel. If the inside 695 of the tube is a mirror, and if the tube is long enough (on the order of ten times the diameter), the energy at the end of the tube will mix well geometrically. That is, any structure of the input beam will be undetectable at output (although the total energy level will drop) due to insufficient airway or liquid falling onto the airway window, for example. Similarly, if the input beam is not precisely at the correct position or at the correct angle, there will be essentially no effect on the output end.

The concept of this embodiment is to place a planar array 697 of narrow bandpass filters and related detectors at the output. The function of the tunnel will distribute the energy symmetrically to the detector. Note that the energy at the output end is radially symmetric, but will be uneven in this area. Since the output of the tube is circular, but the array is square (for four detectors) and further the area of each detector is part of the total output area, the described system is not very efficient. The loss of efficiency can be mitigated by making the tube square to match the detector array or optionally placing a set of channels at the output. These channels will be used as a group to receive all the energy of the pipeline, divide it in a variety of ways to match the number of tunnels, and converge the energy down to the size of the detector. In this figure, the side of the tube (and source mirror) is cut out for description. The detector plane does not show the array.

FIG. 27 is a side view of an embodiment of a four-channel optical system 700 disposed in a linear structure on a substrate 705. As shown in FIG. The infrared rays enter the detector/optical assembly 700 through the lens 710 first. Then, the beam splitters 743, 753, and 763 continuously divide and reflect the infrared rays. The transmitted infrared rays pass through filters 740, 750, and 760, respectively, before entering the detectors 745, 755, and 765. The remaining infrared rays reflected by the focusing mirror 720 and passing through the beam splitter 763 pass through the filter 770 and reach the detector 775. The heaters 735 and 730 are used to maintain the detector block 780 at a constant temperature.

In the above embodiment, a plurality of absorption type detector assemblies are provided to detect various gas components in the gas flowing into the sample chamber. It will be understood that the present invention also considers a single or combined absorption type detector to provide multiple gases for the luminescence quenching type gas detector. Multiple luminescence quenching gas detectors will require multiple sources and detectors, and filters and multiple chemicals are provided on the substrate of the airway adapter.

200780000861.8 Fig. 28 is a perspective exploded view of the optical component 240 of the gas measurement system and the luminescence quenching measurement circuit board 235 with the bracket 232. The detector filter 233 removed from the luminescence quenching optical system 236 is shown in FIG. 29, and is combined to the luminescence quenching measurement circuit board 235. The luminescence quenching measurement circuit board 235 includes a circuit for driving the excitation source 243 and measuring the response of the detectors 238 and 239 using known detection techniques.

Fig. 29 is a perspective exploded view of the luminescence quenching measurement circuit board. This exemplary luminescence quenching optical system 236 includes an excitation source 243, detectors 238 and 239 on each side of the excitation source 243, a detector filter 233, a selective excitation source filter 241, and a shield 234. All components are arranged on the same plane that allows reduction in size and weight. The exemplary excitation source consists of green light emitting diodes. The excitation source 243 and the detectors 238 and 239 are separated from each other by an electric shield and an optical filter. The exemplary detector consists of photodiodes. It will be understood that the present invention contemplates providing a photodetector ring surrounding or partially surrounding the source 243. The ring can be a single detector or multiple detectors and can have a suitable pattern, such as circle, square, triangle, rectangle, etc.

In an exemplary embodiment, the detector filter 233 is a rectangular filter structure having a hole 229 through which rays are emitted from the excitation source. The optical characteristic of the detector filter is that the following radiation wavelengths are basically transmitted through the filter: this radiation involves the quenching of the luminescence of the sensitive film/chemical, and responds to contact with one or more gases to be measured, which will not be involved. This kind of interacting rays basically does not pass through the filter. The detector filter can be band pass, high pass, low pass, or any other filter type known in the prior art. In addition, the optical excitation source filter 241 can be used to limit the radiation emission to the wavelength of the radiation at which the sensitive film is excited so as to prevent unwanted wavelengths from reaching the sensitive film.

Preferably, the sensitive film sensitive to the gas of interest is arranged on a plane parallel to and shifted from the first plane of the exemplary luminescence quenching optical system 236. To minimize the unwanted interaction between the excitation source and the detector, a shield 234 is placed around the excitation source. In the exemplary embodiment, the inner surface of the shield 234 is substantially reflective to the radiation emitted by the excitation source and serves two purposes. This allows it to redirect the external light back to the sensitive film while improving the efficiency of the system. In addition, excitation sources such as LEDs emit light to a larger angle than the opposite of the sensitive film. Preferably, the shape of the shield is set to block light from directly reaching the detector and affect the luminescence measurement.

In the exemplary embodiment shown, the rays emitted from the excitation source 243 are transmitted through the filter 241

200780000861. 8 The sum passes through the hemispherical window 247 and is incident on the sensitive film. Based on the concentration of oxygen, the sensitive film emits radiation at different wavelengths, and the radiation is transmitted back through the window 247 and filtered by the detector filter 233 and measured by two detectors provided in the detector filter 233.

In addition, an index matching layer (not shown) can be optionally placed between the detector and the detector filter to minimize reflection loss. The radiation emitted by the sensitive film is emitted in all directions and only a small part of the emitted radiation is directed to the detector. Due to Fresnel reflection, the rays are further attenuated at each interface along the optical path. Therefore, filling the air gap with a material such as an index matching material allows this reflection loss to be minimized.

The heater flexible circuit 245 is electrically connected to the luminescence quenching detection circuit board 235 as described above. Because temperature affects the amount of light emitted by the sensitive film, temperature control or compensation is required. To maintain a constant temperature on the film, the window heater 245 thermally communicates with the flat side of the window 247, which is generally sapphire. The heater maintains the window 247 at a constant temperature, which in turn maintains the temperature of the sensitive film. The window heater 245 is designed in a ring shape to be kept outside the light path. The window 247 is hemispherical rather than flat to improve thermal contact with the sensitive film. The close contact between the two elements and the curved profile also has the effect of improving the amount of light transmitted through the sensitive membrane and back to the detector. As described above, an exemplary embodiment of the luminescence quenching optical system 236 suitable for use in the present invention is disclosed in the '451 application.

It will be understood that the luminescence quenching feature of the present invention and the absorption feature of the present invention can be employed alone or in combination and in a side flow structure.

Now consider several alternative structures of the present invention. For example, the present invention considers using a prism or an aspheric lens before the excitation source to distribute light more evenly on the sensitive film. It is also considered to exchange the positions of the excitation source and the detector, that is, to use a single large detector surrounded by two or more excitation sources. The present invention also considers turning or tilting the detector so that the detector surface is substantially perpendicular to the radiation emitted from the luminescent material to improve detection efficiency.

The present invention also considers providing a display 800 on the cover of the gas measurement system (see FIG. 3). The display can be any suitable display, such as LEDs, OLEDs, LCDs, and so on. Providing a display on the cover on the gas measurement system allows physicians or other users to display warning or report information, waveforms, trends, and other related information directly from the unit near the patient without having to reposition themselves to see the conventional monitoring screen, because In conventional systems, the monitor screen is usually a few feet away from the patient, so this is usually

200780000861.8 The first is necessary. This is particularly important in adverse medical events that require urgent attention and physician response.

Although the present invention has been described in detail for descriptive purposes based on what is now considered to be the most practical and preferred embodiment, it will be understood that the details are only used for this purpose and the present invention is not limited to the disclosed embodiments, but on the contrary, it is desired to cover additional Changes and equivalent arrangements within the essence and scope of the claims. For example, it will be understood that the present invention considers combining one or more features of any embodiment with one or more features of any other embodiment as much as possible.

200780000861.8