WO2010025600A1 - 高灵敏度与高选择性气体传感器 - Google Patents

高灵敏度与高选择性气体传感器 Download PDF

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WO2010025600A1
WO2010025600A1 PCT/CN2008/073385 CN2008073385W WO2010025600A1 WO 2010025600 A1 WO2010025600 A1 WO 2010025600A1 CN 2008073385 W CN2008073385 W CN 2008073385W WO 2010025600 A1 WO2010025600 A1 WO 2010025600A1
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gas
sample
sensor
measured
gas sensor
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PCT/CN2008/073385
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English (en)
French (fr)
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韩杰
沈立军
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无锡尚沃生物科技有限公司
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Publication of WO2010025600A1 publication Critical patent/WO2010025600A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment

Definitions

  • the present invention relates to the field of gas sensors, and more particularly to gas sensors having high sensitivity and high selective detection performance for a gas to be measured. Background technique
  • Gas detection in the field of environmental and health safety often requires high sensitivity and high selectivity gas sensors.
  • concentration of benzene and formaldehyde in the living or working environment shall not exceed 90 ppb.
  • the concentration of benzene and formaldehyde in the living or working environment shall not exceed 90 ppb.
  • the lower limit and accuracy of the concentration of nitric oxide in exhaled breath must be Less than 5ppb.
  • the main requirements for this type of testing are large laboratory analytical instruments that are difficult to use on-site.
  • the portable sensor detector that can be used in the field does not meet the sensitivity requirements, and usually only gas with a concentration higher than lOOOOppb or lppm can be detected. When trying to increase sensitivity for lower concentration detection, sensor selectivity is reduced.
  • the Chinese patent No. 200510049517.0 discloses a portable sensor gas analyzer for the detection of low concentrations of formaldehyde and benzene gases in the environment.
  • the invention uses a gas enrichment device in front of the sensor to increase the concentration of the gas to be measured, so that the sensor which can only detect a high concentration can be combined with the simulation calculation method for the analysis of the low concentration gas.
  • This invention reduces the detection limit of oxide semiconductor and carbon nanotube sensors from the original lppm to 10-100 ppb.
  • this method must accurately select the gas-enriched adsorbent material and determine the degree of enrichment, and also requires a program temperature control to achieve a quantitative gas adsorption and desorption process, and carry the enriched gas with a carrier gas such as nitrogen. Inspection, analyzer structure and operation are very complex, even more than portable gas chromatography analyzers.
  • Chinese Patent Publication No. CN1681 635 discloses a portable sensor gas detector for the detection of nitric oxide in exhaled breath.
  • the invention designs a special fluid gas path, including a flow regulating and steady flow device, a humidity control device for humidity control of a gas sample by using a DuPont NAFION tube and a surrounding filling medium, and a semiconductor refrigerant sheet for gas sample and electrochemical A thermostat that controls the temperature of the gas sensor. Due to the precise and quantitative control of airflow, pressure, temperature and humidity, combined with the interference device for the interference gas, the lower limit and accuracy of the detection of nitric oxide concentration is 5 ppb.
  • the detector product capable of detecting low-concentration formaldehyde gas is mainly the xp-308 detector of Japan New Universe Co., Ltd., and the detection limit can reach 10 ppb.
  • the detector is equipped with two filters before the traditional electrochemical formaldehyde gas sensor. One filter removes only formaldehyde and the other does not remove formaldehyde, but instead balances diffusion resistance.
  • the ambient gas is sampled twice, and then passed through two filters and then detected by the gas sensor.
  • the difference between the two detection signals is the concentration of formaldehyde.
  • the difference method deducts the influence of the interference gas in the gas sample to some extent, thus improving the sensitivity and selectivity of the detection.
  • the present invention has developed a high sensitivity and high selectivity gas sensor in view of the deficiencies of the prior art including the above invention.
  • the sensor does not require an enrichment device for increasing the concentration of the gas to be measured, and does not require precise control of gas, temperature, humidity, pressure, etc. of the gas sample.
  • the device does not need to be sampled separately.
  • the sensor proposed by the invention only needs one sampling of the circulating gas path to perform two measurements, thereby effectively eliminating the influence of interference gas, air flow, temperature, humidity and pressure, and achieving high sensitivity and high selectivity detection.
  • the gas sensor provided by the present invention comprises: a gas pump for sampling and transporting gas for detection and discharge, a gas sensor for detecting a gas sample, a filter capable of removing a gas to be measured, and a sample for temporarily storing a gas sample. Chamber and airflow direction control valves, and a circulating air path formed by them between the gas sample inlet and outlet.
  • the gas sample is first detected by the gas inlet through the gas sensor.
  • the detected signal may contain other gas components and the temperature, humidity, pressure and gas flow state of the environment or gas itself, in addition to the contribution of the gas to be measured. influences.
  • the gas after the detection is then passed through the filter to remove the gas to be tested and returned to the gas sensor for a second detection.
  • the detected signal no longer contains the contribution of the gas to be measured, but only contains the unremoved interference gas and temperature. , humidity, pressure and airflow speed effects. Therefore, the difference between the two tests contains only the signal of the gas being measured, minus the effect of all the two measurements remaining the same.
  • a sample chamber is set up to temporarily store the gas sample, and the constant flow of the air pump and the control valve is utilized to maintain the same air flow and temperature as one measurement. Degrees, humidity, pressure, and conditions of interfering gases are measured twice.
  • the sample chamber volume should account for more than 99% of the total volume of the circulating gas path, and it must be ensured that the gas in the sample chamber is completely replaced by the gas sample after one measurement.
  • the advantage of the present invention is that the complexity and cost of system design and operation are significantly reduced and reliability is increased compared to gas sensor technology employing gas enrichment or using constant current, constant pressure, constant temperature and constant humidity devices.
  • An advantage of the present invention is that it avoids the detection errors resulting from two samples and the inconsistencies in the results compared to sensor techniques that employ two separate samples for analysis.
  • the sensor provided by the invention is easy to integrate and modular, and is suitable for the production of existing sensor gas detector production lines, and maintains the convenience of using such products.
  • Figure 1 is a structural diagram of the high sensitivity and high selectivity gas sensor of the present invention
  • the detection signals of commonly used electrochemical, metal oxide and carbon nanotube semiconductors and catalytic combustion type gas sensors mainly reflect the mass transfer or reaction rate associated with the measured gas concentration.
  • the most important factors affecting this rate are temperature, humidity, pressure, gas flow state and other gases (commonly known as interfering gases) that may be involved in the reaction or mass transfer process.
  • interfering gases commonly known as interfering gases
  • the most important feature of the present invention is a circulation gas path composed of a gas sensor, a sample chamber and a filter for removing the gas to be measured, and the air flow state is controlled by the air pump and the control valve, thereby eliminating the difference method by two measurements.
  • Various types of interference effects enable high sensitivity and high selectivity detection.
  • Figure 1 is a structural view of a highly sensitive and highly selective gas sensor of the present invention.
  • the sensor comprises an air inlet 1, a three-way valve 2 and 7, an air outlet 8, an air pump 3, a gas sensor 4, a sample chamber 5 and a filter 6. They form a circular gas path between the inlet and outlet.
  • the gas sample flows from the air inlet 1 through the control valve 2 to the air pump 3, and enters the gas sensor 4 for detection.
  • the detection signal includes the gas to be measured and the interference factor.
  • the gas sensor of the present invention is connected in series with a sample chamber. According to Fig. 1, the gas detected by the gas sensor 4 continuously enters the sample chamber 5, and pushes the other gas originally existing inside to be vented through the outlet 8 through the control valve 7 in the form of a plug flow.
  • the air path for one test is 1234578.
  • the time of one test must be greater than the full response time of the gas sensor.
  • the detected gas volume is the product of the detection time and the gas flow rate.
  • the gas path 23457 mainly the capacity of the sample chamber, must be smaller than the sample gas volume to ensure that the other gas originally present in the detection gas path is completely replaced by the gas sample, and the sample chamber is completely filled with the gas sample without other gas.
  • the inlet and outlet ports 1 and 8 are closed by the control valves 2 and 7, respectively, and the circulation gas path 576234 is opened.
  • the air pump 2 continues to drive the sample gas from the sample chamber 5 to the filter 6 to remove the gas to be measured, and then to the gas sensor 4 for detection.
  • the time during which all five gases in the sample chamber pass through the filter 6 and the gas sensor 4 is the sample chamber volume divided by the gas flow rate.
  • the time of the secondary detection must be greater than the full response time of the gas sensor to the sample from which the gas to be measured is removed. Depending on these time values, the secondary test may require multiple cycles until a stable test value is obtained.
  • One method proposed by the present invention is to maintain the entire gas path, mainly in a turbulent state in which the state of the gas flow in the sample chamber is a flat distribution of the plug flow or the gas flow velocity. In this state, according to the principles of fluid mechanics, the gas will not produce significant mixing (called back mixing or axial mixing) along the flow direction.
  • One way is to use an elongated pipe for a fixed flow rate.
  • the gas sensor 4 and the air pump 3 must be placed on the side of the gas path separated by the gas valves 2 and 7, and the filter 6 is placed on the other side.
  • the air pump 3, the gas sensor 4 and the sample chamber 5 can be interchanged with each other.
  • the sample chamber 5 can also be placed on one side of the filter 6 or even an elongate line connecting some or all of the components, including the nozzle.
  • the positional change of the sample chamber is reflected on the time curve of the gas sensor output signal.
  • the output signal from the sensor provided in Figure 1 is primarily the response to the gas sample being measured. If the position of the air pump 3 and the sample chamber 5 in Fig.
  • the initial output signal is first of all a response to the gas originally stored in the sample chamber 5, This is followed by a response to the gas sample being tested.
  • the choice of the location of the sample chamber will depend on the specific application requirements.
  • the sample chamber is upstream of the sensor.
  • the air pump 3 described in the present invention is mainly a gas sampling pump which is usually employed in a sensor gas detector.
  • the sensor structure In addition to meeting the installation requirements of the supplier, such as the use of air intake filter at the air inlet to remove dust and other harmful substances affecting the pump delivery performance, the sensor structure must also consider the requirements of the flow rate and steady flow of the air pump. This requirement is mainly reflected in the pressure drop of the airflow through the sample chamber and the pulsation of the airflow state that may be caused when the two detections are switched.
  • other gas delivery methods such as microfans or fans, and micromotors that are driven by gears or wheels, can also be used in place of the micropump.
  • the gas valves 2 and 7 described herein can be manually, pneumatically, electromagnetically and mechanically adjusted in direction and flow or pressure control valves. In view of the degree of automation, a solenoid valve is preferred.
  • the two two-position three-way solenoid valves in Figure 1 can also be replaced with simple two-way solenoid valves.
  • the three-way valve 2 can be replaced by two two-way valves, which are respectively mounted on the side of the inlet 1 and the gas filter 6, and are in a normally-on and normally-closed state, respectively. When switching from one detection to the second detection, the two valves are energized at the same time, and are switched to the closed and on states respectively.
  • a similar three-way valve 7 can also be replaced by two two-way valves, or even a normally-on two-way valve mounted at the outlet 8. At the time of one measurement, since the gas path on the side of the filter 6 is closed, the gas can still be vented from the outlet 8 only through the valve. During the second measurement, the solenoid valve is energized to close.
  • a three-way valve can be replaced by a two-way valve and one or two check valves.
  • the materials of all the other components are inert to the gas to be measured, and do not cause any enrichment or dilution of the gas to be measured.
  • the filter 6 is composed of an adsorbent and a catalyst which can detect the gas in the gas sample by adsorption or reaction, and the specific selection will be determined according to the specific application, and the removal efficiency can also be repeated several times. And improve. If the selected gas sensor consumes the gas to be measured, the gas filter can even be dispensed with, and the gas sensor can effectively remove the gas to be measured by the cyclic measurement method described in the present invention.
  • the high-sensitivity and high-selective sensor described in the present invention provides a flexible and wide selection and design space for the gas sensor, the air pump, the sample chamber, the control valve, etc., which can meet different application requirements and be convenient for specific Implementation.
  • the invention only proposed to detect one or two specific gases with high sensitivity or high selectivity of a specific gas sensor or sensor.
  • the following application examples will further illustrate the advantages of the application of the invention and the ease of implementation.
  • Application Example 1 This example is intended to illustrate how the present invention detects the concentration of nitric oxide in the ppb range of exhalation. Exhaled nitric oxide, a marker of airway inflammation, can be used to diagnose and track respiratory diseases such as asthma. European and American countries have also developed standards to encourage and recommend such non-immersion diagnostic techniques, and the requirements for detection accuracy and lower limit must not exceed 5 ppb.
  • a nitric oxide electrochemical gas sensor is used.
  • the gas sensor is currently widely used for industrial safety and environmental gas detection. Since many gases in air or exhalation, such as CO, CO2, NO2, oxygen, etc., can produce a response contribution in the range of 10 to 100 ppb, the detection limit and accuracy of the gas sensor are around 0.1-1 ppm. However, in the laboratory, the gas distribution without any interfering gas is used, and the temperature of the gas distribution (22 degrees) and humidity (70%) and the temperature of the gas sensor (22 degrees) are strictly controlled. The lower limit and accuracy of the gas sensor are detected. Can reach 5 -10 ppb.
  • the test device of this embodiment is shown in Fig. 1.
  • the filter 6 is formed by pressing a porous filler such as potassium permanganate, and can filter nitric oxide to a concentration of less than 5 ppb.
  • the air pump 3 uses a domestically produced GminiP model domestic micro air pump, 18 grams in weight and a maximum size of 20 mm.
  • the control valves are 2 and 7 are commercially available miniature two-position three-way solenoid valves.
  • the sample chamber 5 is a Teflon tube having an inner diameter of 6 mm and a length of 70 cm and a capacity of 20 ml. The connections of the components are all connected to the Teflon interface.
  • This embodiment conducted two sets of experiments using the sensor test apparatus formed in accordance with Fig. 1.
  • One group is made using a known concentration of gas in the laboratory. The other group was to test the exhalation of volunteers. Breath samples were obtained from air bag sampling in the expiratory nitric oxide test procedure recommended by the European and American 2005 standards. A 500 ml Teflon sampling bag supplied with inlet and outlet valves is available on the market. For comparison, a chemiluminescence spectrometer (US General Electric Apparatus, model NOA280), which is called a nitric oxide analysis gold standard, was also used. All tests were carried out in indoor conditions. The gas flow rate of the test device of the present invention was 3 ml/sec. The total detection time is 2 minutes.
  • Figure 2 shows the two sets of results: One is the comparison of two test methods for the known concentration of nitric oxide (nitrogen as a carrier gas) (top), the other is The results of the detection of three breath samples respectively (the following figure are the three sets of three response curves, respectively).
  • the first set of tests shows that the test device and the chemiluminescence method of the present invention are both in the concentration range of 0 to 300 ppb.
  • the known gas distribution concentration is basically the same, and the error of the average value of the two methods does not exceed l ppb, which is within the resolution and precision of the chemical spectrometer.
  • the detection limit and accuracy of the test device of the present invention are 2-3.
  • Ppb the value close to the chemiluminescence method. Comparing the results of the three breath samples in the lower graph of Fig. 2, it can be seen that the present invention Sensor test apparatus exhibits a higher noise (pulsation). The reason is that the measurement circuit of the electronic signal and influence airway airflow conditions possible fluctuations.
  • This example is intended to illustrate how the present invention detects formaldehyde concentrations in the ppb range of air.
  • the highest concentration required by environmental regulations shall not exceed 80 ppb, and the accuracy of the test analysis shall be at least 10 ppb.
  • the problems in this environmental test are: Standard chemical spectrophotometer and gas chromatograph can meet the analytical requirements, but it is difficult to carry to the field; the sensor detector that can be carried to the field can not meet the analysis requirements, can only be used Qualitative alarm safety monitoring of environmental pollution.
  • the gas sensing element can have a detection limit of 10 ppb in a strictly controlled laboratory gas distribution and detection environment.
  • the reliable and stable concentration detection range is above 100 ppb.
  • Another significant problem with all current electrochemical gas sensors is the rapid attenuation of sensitivity and humidity. The effect of temperature and interfering gases on the response of the gas sensor is not negligible. This embodiment shows that the present invention can not only improve the sensitivity and selectivity of detection, but also improve the stability and reliability of detection.
  • the test device of this embodiment is shown in Fig. 1.
  • the air pump, sample chamber, control valve and take-over settings in Application Example 1 are still used in this application example.
  • the formaldehyde filter used consists of a porous material composed of a mixture of sodium hydrogen sulfite and alkali lime, which is capable of filtering formaldehyde to a concentration of less than 10 ppb.
  • test apparatus of the present invention is substantially close to or achieves the analytical performance of gas chromatography, and the lower limit of detection and resolution that can be achieved under laboratory conditions is substantially 10 ppb.
  • a prominent problem with formaldehyde electrochemical detectors today is the rapid zero and sensitivity drift.
  • the advantages of the test device of the present invention in this respect are more prominent. For example, samples of the same concentration are tested at the same time every day for 7 days, while the cumulative change in response signal of the device of the present invention is less than 3%.
  • the electrode activity of the electrochemical gas sensor in the conventional gas detector is combined with the influence of humidity and interference gas, causing zero point and sensitivity drift, requiring frequent and timely calibration.
  • the sensor of the present invention effectively eliminates these effects for each detection, it is still possible to maintain high sensitivity and zero point correction is no longer required.
  • This example is intended to illustrate how the present invention detects the concentration of benzene vapor in the ppb range of ambient air.
  • the maximum concentration required by environmental regulations shall not be higher than 90 ppb, and the lower limit and accuracy of the test analysis shall be 10 ppb.
  • a single-walled carbon nanotube semiconductor gas sensor prepared by the inventors is selected, and the carbon nanotube modified by palladium-ruthenium metal is dispersed on the platinum electrode.
  • the gas sensing element has a linear range of detection of benzene in nitrogen of from 100 to 5000 ppb at room temperature. Further experimental evaluations show that the effects of changes in humidity, oxygen and nitrogen oxide concentrations in the air on the gas sensor are significant, can cause magnitudes of 10 - 100 ppb and greater interference, and the effects of humidity also cause zero or baseline Severe drift.
  • the low selectivity, especially the sensitivity to humidity, of carbon nanotube semiconductor gas sensors is a significant problem reported in many literatures and is also the main reason why they are still in the laboratory development stage. This embodiment shows a solution to this problem.
  • the test device of this embodiment is shown in Fig. 1.
  • the air pump, control valve and take-over settings in Application Example 1 are still used in this application example.
  • the response time and recovery time of carbon nanotube semiconductor gas sensors are relatively long, close to 30 and 60 seconds, respectively.
  • the filter packing is a TENAX gas chromatographic column packing for adsorbing benzene-based organic substances, and is a porous polymer carrier of 2,6-diphenyl-p-phenylene ether.
  • the benzene organic vapor in the air is collected by using the TENAX adsorption tube, and then taken back to the laboratory for heating and desorption, and the benzene organic content is determined by a gas chromatograph.
  • the gas distribution of benzene vapor was carried out in accordance with the National Standard "Air Quality Determination of Toluene, Xylene, and Styrene by Gas Chromatography" (GB14677). At the same time, the analysis was carried out using the gas chromatograph (Agilent 7890) method described in the standard. The test data of Fig. 4 was compared with the gas chromatographic analysis value as the concentration standard (the abscissa in the figure), and the test performance of the test apparatus of the present invention in the range of 0-1000 ppb benzene concentration was compared.
  • test apparatus of the present invention is substantially close to or achieves the analytical performance of gas chromatography, and the lower limit of detection and resolution that can be achieved under laboratory conditions is substantially 10 ppb.
  • the average error (about 5 ppb) of the test apparatus of the present invention and the gas chromatograph is substantially within the accuracy range of the chromatograph itself.
  • This example is intended to illustrate how the present invention detects the concentration of acetone in the range of ppb in exhalation.
  • acetone has been a concern for diabetes as a marker of diabetes.
  • the concentration indicates the degree of disease.
  • the concentration of acetone in the breath of diabetic patients is higher than 1 ppm or 1000 ppb, which is needed for early diagnosis of diabetes.
  • the concentration detected must be much smaller than this value, for example up to 100
  • the lower detection limit of ppb and the detection accuracy of 100 ppb organic vapors such as acetone and benzene are also required by the regulations for exhalation testing of personnel exposed to such gases.
  • the specified lower limit of detection is 480 ppb. Such requirements are usually only met by laboratory analytical instruments.
  • Some include oxide semiconductors and photoionized gas sensors that detect low concentrations of acetone, but their selectivity is extremely poor, and the measured signal contains almost the same level of contribution from gases of similar structure or nature, so it simply cannot Gases for very selective and reliable requirements are especially breath detection.
  • This application embodiment shows a solution.
  • the single-walled carbon nanotube semiconductor gas sensor selected in this embodiment is substantially the same as that described in the third embodiment.
  • the palladium-ruthenium alloy used to modify the carbon nanotubes differs from the aging heat treatment process of the gas sensor in order to obtain higher selectivity for acetone.
  • the voltage or current output of the gas sensor in the range of acetone concentration 0 - 5 ppm (ie 5000 ppb) is substantially linear, and the contribution of humidity and interference gas is also significant. The change in humidity causes a significant drift in the detection zero or baseline.
  • the implementation of this embodiment is also basically the same as that of the third embodiment.
  • the inventor also tested the breath sample after inhaling acetone-containing air.
  • the test was carried out in accordance with the sampling and analysis methods specified in the Chinese Ministry of Health industry standard “Gas Chromatographic Method for Determination of Acetone in Exhaled Gas” (Standard No. WS/T175-1999).
  • the present embodiment is provided with a filter for filtering microbial bacteria and particles in the exhalation at the air inlet, and a 3A activated carbon for appropriately reducing the saturated humidity in the exhalation and adsorbing the water molecules. Filter.
  • the results of the test are shown in Figure 5.
  • the gas chromatograph and the sensor detecting device of the present invention are consistent in the concentration detection of acetone vapor in the concentration range of the test detection of 0-5 ppm.
  • the average difference between the two lies within the accuracy range of the gas chromatograph itself.
  • the lower limit of detection of the sensor test apparatus of this embodiment can reach 200 ppb or 0.2 ppm.
  • the concentration of volunteer exhalation in Figure 5 is below lppm, indicating no diabetes problems.
  • the existing gas sensor, gas sensor and gas detector can greatly improve the sensitivity and selectivity, and close to, or even exceed, the detection performance of the laboratory analysis instrument including the gas chromatograph, and maintain It has the characteristics of convenient carrying and simple operation.
  • This significant, even intrinsic, improvement not only satisfies the ever-increasing requirements for the detection of gas sensors in industrial environmental safety, but also allows gas sensors to enter applications such as the environmental safety and health testing described above in the application examples.

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Description

高灵敏度与高选择性气体传感器
技术领域
本发明涉及气体传感器领域， 更具体地说， 涉及对被测气体具有高灵 敏度与高选择性检测性能的气体传感器。 背景技术
环境与健康安全领域涉及的气体检测通常需要高灵敏度与高选择性 气体传感器。 例如， 为防止中毒或保证健康安全， 生活或工作环境中苯与 甲醛的浓度规定不得超过 90 ppb; 而对于哮喘等呼吸病的呼气检测， 呼气 中一氧化氮浓度的检测下限与精度必须低于 5ppb。 目前能够满足这种检测 要求的主要是难以现场使用的大型实验室分析仪器。 而可以现场使用的便 携式传感器检测仪却满足不了灵敏度要求， 通常只能检测到浓度高于 lOOOppb或 lppm的气体。 当试图提高灵敏度用于较低浓度检测时， 传感器 选择性则随之降低。 此时， 传感器检测信号中， 环境与气体样品的温度、 湿度、 气流、 压力以及其它气体的贡献接近甚至超过被测气体的响应， 以 至于无法区分而失去选择性。 解决灵敏度与选择性的矛盾问题一直是气体 传感器检测技术研究与应用开发的首要任务。
申请号为 200510049517.0的中国专利公布了一种便携式传感器气体 分析仪， 用于环境中低浓度甲醛和苯系气体的检测。 该发明在传感器之前 采用气体富集装置， 提高被测气体的浓度， 从而使本来只能检测高浓度的 传感器可以结合模拟计算的方法用于低浓度气体的分析。 该发明使氧化物 半导体与碳纳米管传感器的检测下限从原来的 lppm 降低到 10-100ppb。 然而这种方法必须精确的选择对气体富集的吸附材料与确定富集的程度， 而且还需要采用程序温控实现定量的气体吸附和脱附过程， 用氮气等载气 携带富集的气体进行检测， 分析仪结构与操作均十分复杂， 其程度甚至超 过便携式气相色谱分析仪。
公开号为 CN1681 635的中国专利（对应的美国专利申请号 US20O10082872) 公布了一种便携式传感器气体检测仪， 用于呼气中一氧化氮的检测。 该发 明设计了特殊的流体气路， 包括流量调节稳压稳流装置、 采用美国杜邦公 司 NAFION管与周围填充介质对气体样品进行湿度控制的恒湿装置、 以及 半导体制冷片对气体样品以及电化学气敏元件进行温度控制的恒温装置。 由于气流、 压力、 温度与湿度等得到精密定量的控制， 结合对干扰气体的 过滤装置， 对一氧化氮浓度的检测下限与精度达到 5ppb。然而这种方法必 须依靠精心设计与加工的湿度、温度、压力、流量与气体过滤等控制装置， 使得检测仪结构十分复杂、 成本显著增加， 而且只能在室内条件下实现有 效的恒温与恒湿控制， 限制了其应用范围或条件。
能够检测低浓度甲醛气体的检测仪产品主要是日本新宇宙公司的 xp-308检测仪， 检测下限可以达到 10ppb。 该检测仪在传统的电化学甲醛 气敏元件之前配备了 2个过滤器。 一个过滤器仅除去甲醛， 另一个过滤器 不除去甲醛， 而是用于平衡扩散阻力。 检测时对环境气体先后两次取样， 分别通过二个过滤器后由气敏元件分别进行检测。 两个检测信号的差值即 为甲醛的浓度。 该差值法一定程度上扣除了气体样品中干扰气体的影响， 因此提高了检测的灵敏度与选择性。 但由于两次检测需要的两次取样条件 (温度、 湿度、 压力与干扰气体等） 并不完全一致 （相当于分析的是两个 样品） ， 因此作为差值的检测结果含有两个样品之间的差异， 而这种差异 对高灵敏度检测的一致性要求是不容忽略的。 此外， 由于两次取样需要用 户人为的操作控制， 也可能产生因人而异的测量误差等问题。 发明内容
本发明针对目前技术包括上述发明的不足开发了一种高灵敏度与高 选择性气体传感器。 与先前技术明显不同的是， 在使用传统气敏元件的基 础上， 该传感器不需要用来提高被测气体浓度的富集装置， 不需要对气体 样品进行气流、 温度、 湿度、 压力等精密控制的装置， 也不需要分别两次 取样。 本发明提出的传感器仅需要一次取样的循环气路进行两次测量， 便 可以有效地消除干扰气体、 气流、 温度、 湿度与压力等影响， 实现高灵敏 度与高选择性的检测。
本发明提供的气体传感器包括： 一个用来取样并输送气体进行检测和 排放的气泵、 一个对气样进行检测的气敏元件、 一个能够除去被测气体的 过滤器、 一个临时存放气体样品的样品室与气流方向控制阀， 以及由它们 在气体样品进出口之间构成的一个循环气路。
气体样品由进气口流经气敏元件进行第一次检测， 检测的信号除了含 有被测气体的贡献外， 还可能含有其它气体组分以及环境或气体本身温 度、 湿度、 压力与气流状态的影响。 该次检测后的气体然后通过过滤器除 去被测气体后回到气敏元件进行第二次检测， 此时检测的信号不再含有被 测气体的贡献， 而仅含有未除去的干扰气体以及温度、 湿度、 压力与气流 速度的影响。 因此两次检测的差值仅含有被测气体的信号， 减去了所有两 次测量保持相同的因素的影响。 因此设置一个样品室， 用来临时存放气体 样品， 并利用气泵和控制阀的恒流作用， 保持与一次测量相同的气流、 温 度、 湿度、 压力以及干扰气体的条件， 进行二次测量。 为保证测量精度， 样品室体积应占循环气路总体积 99%以上， 而且必须保证在一次测量后样 品室内的气体被气体样品完全置换。
相比于采用气体富集或者采用恒流、 恒压、 恒温与恒湿装置的气体传 感器技术， 本发明的优点是系统设计和操作的复杂程度与成本均显著降 低、 而可靠性增加。 相比于采用分别两次取样进行分析的传感器技术， 本 发明的优点是避免了两次取样产生的检测误差以及结果的不一致性问题。 与所有先前技术相比， 本发明提供的传感器便于集成化与模块化， 适合于 现有传感器气体检测仪生产线生产， 并保持了该类产品使用方便的特点。 本发明上述的以及其它的特征、 性质和优势将通过下面结合附图、 具 体实施说明以及实施例的描述而变得更加明显。 附图说明
将参照附图结合在下面的具体实施说明、 实施例与权利要求更加详细 地描述本发明。 在附图中， 相同的附图标记始终表示相同的特征， 其中： 图 1是本发明的高灵敏度与高选择性气体传感器结构图；
图 2 是本发明实施应用例一对呼气一氧化氮的检测结果；
图 3是本发明实施应用例二对环境甲醛气体的检测结果；
图 4是本发明实施应用例三对环境中苯蒸汽的检测结果；
图 5是本发明实施应用例四对呼气丙酮蒸汽的检测结果； 具体实施方式
常用的电化学、 金属氧化物与碳纳米管半导体以及催化燃烧型气敏元 件的检测信号主要反映的是与被测气体浓度相关的传质或反应速率。 除了 被测气体外， 影响这一速率最主要的因素是温度、 湿度、 压力、 气流状态 与可能参与反应或传质过程的其它气体 （通称干扰气体） 。 对于 ppm数量 级的检测， 这些因素的影响大部分是可以接受的， 而对于 ppb数量级的检 测， 这些因素的影响与响应信号相比已不可忽略， 因此有必要进一步消除 或更精确的量化这些影响。本发明最主要的特征是由气敏元件，样品室与除 去被测气体的过滤器构成的循环气路， 并利用气泵与控制阀实现气流状态 的控制， 从而通过两次测量的差值方法消除各类干扰效应， 实现高灵敏度 与高选择性的检测。 图 1是本发明的高灵敏度与高选择性气体传感器的结构图。 该传感器 包括进气口 1、 三通阀 2与 7、 出气口 8、 气泵 3、 气敏元件 4、 样品室 5 与过滤器 6。 它们在进出口之间形成一个循环气路。
第一次检测时， 气体样品从进气口 1流经控制阀 2到气泵 3， 进入气 敏元件 4接受检测， 检测信号包括被测气体与干扰因素两部分贡献。 与传 统或其它发明提及的传感器设计最为不同的是， 本发明的气敏元件串联了 一个样品室。 按图 1， 经气敏元件 4检测的气体连续的进入样品室 5， 并 推动内部原来存在的其它气体以活塞流的方式通过控制阀 7经出口 8 放 空。 一次检测的气路为 1234578。 一次检测的时间必须大于气敏元件完全 的响应时间。检测的气体容量为检测时间与气体流量的乘积。气路 23457、 主要是样品室的容量必须小于样品气量以保证该检测气路中原来存在的 其它气体被气体样品完全置换， 时该样品室全部充满气体样品而无其它气 体。
一次检测结束时， 由控制阀 2与 7分别关闭进、 出气口 1与 8， 开通 循环气路 576234。此时气泵 2继续驱动样品气体由样品室 5到过滤器 6除 去被测气体， 然后到气敏元件 4进行检测。 将样品室 5种气体全部经过过 滤器 6与气敏元件 4的时间为样品室容积除以气体流量。 二次检测的时间 必须大于气敏元件对除去被测气体的样品的完全响应时间。 取决于这些时 间数值， 二次检测可能需要多次循环， 直至获得稳定的检测数值。
为保证检测结果的可靠性， 必须避免气体样品与气路中原来存在的气 体的混合效应。 本发明提出的一种方法是保持整个气路、 主要使样品室中 的气流状态均为活塞流或气流速度呈平坦分布的湍流状态。 该状态下， 按 流体力学原理， 气体沿流动方向将不产生显著的混合 （称为返混或轴向混 合） 。 其一种方式是对固定的流速采用细长的管道。 当气体样品由进气口 1进入气路后，便以活塞流的方式推动原来存在于气路与样品室中的气体， 并经出气口 8排空， 而气体样品则占据气路与样品室所有的空间。 也可以 使用其它活塞流装置、 包括设有挡板的流动装置与列管流动装置。
按本发明， 必须将气敏元件 4与气泵 3放置在气体阀门 2与 7分隔的 气路一侧， 而过滤器 6放置在另外一侧。 除此之外， 气泵 3、 气敏元件 4 与样品室 5可以相互调换位置。 样品室 5也可以放在过滤器 6的一侧或甚 至一个连接部分或全部部件的细长管路， 包括接管。 样品室的位置变动会 反映到气敏元件输出信号的时间曲线上。 图 1提供的传感器开始的输出信 号主要是对被测气体样品的响应。如果将图 1 中气泵 3与样品室 5的位置 互换， 则开始的输出信号首先是对原来存放在样品室 5中气体的响应， 其 后才是对被测的气体样品的响应。 样品室的位置的选择将视具体的应用要 求而定。 优选为样品室在传感器上游。
本发明描述的气泵 3主要是传感器气体检测仪通常采用的气体采样 泵。 使用时除了满足供货商要求的安装条件、 例如在进气口采用进气过滤 器除去灰尘等影响气泵输送性能的有害物质外， 还必须考虑该传感器结构 对气泵流量大小与稳流的要求。 这种要求主要体现在气流通过样品室压降 以及当两次检测切换时可能引起的气流状态的脉动。 按本发明， 其它气体 输送方式、 例如微型电扇或风机、 微型电机通过齿轮或轮盘驱动的活塞充 气 （抽气） 装置也可代替微型气泵使用。
本发明描述的气体阀门 2与 7可以是手动、 气动、 电磁与机械调节的 方向与流量或压力的控制阀。 考虑到自动化程度， 优选的是电磁阀。 图 1 中两个二位三通电磁阀也可以用简单的开关式二通电磁阀取代。 例如， 三 通阀门 2可以用两个二通阀取代， 分别安装在进口 1与气体过滤器 6的一 侧， 并分别处在常通和常闭的状态。 从一次检测切换到二次检测时， 这两 个阀门同时通电动作， 分别切换到闭和通的状态。 类似的三通阀门 7也可 以用两个二通阀、 甚至一个安装在出口 8处的常通型二通阀取代。 一次测 量时， 由于过滤器 6—侧的气路被关闭， 气体仍然只能通过该阀门从出口 8放空。 二次测量时， 该电磁阀被通电关闭。 此外， 一个三通阀也可以被 一个二通阀与一个或两个单向阀取代。
本发明描述的传感器中除气体过滤器外， 其余所有部件的材质对被测 气体都是惰性的， 不产生对被测气体有任何增浓或稀释的作用。 而过滤器 6则是由对被测气体能够通过吸附或反应去处气体样品中被测气体的吸附 剂与催化剂构成， 具体的选用将根据具体的应用而定， 去除的效率也可以 通过多次循环而提高。 如果选择的气敏元件消耗被测气体， 该气体过滤器 甚至可以省去， 由该气敏元件通过本发明描述的循环测量的方式有效的去 除被测气体。
本发明描述的高灵敏度与高选择性传感器对其中的气敏元件、 气泵、 样品室、 控制阀等均提供了较为灵活与广泛的选择和设计空间， 既能满足 不同的应用要求、 又便于具体实施。 而以往的发明则仅是提出一个特定的 气敏元件或传感器高灵敏度或高选择性的检测一中或两种特定的气体。 下 面的应用实施例将进一步体现本发明应用面广并且便于具体实施的优势。 应用实施例一 本例用来说明本发明如何检测呼气中 ppb范围内的一氧化氮浓度。 呼 气一氧化氮作为气道炎症的标志物可以用来诊断与跟踪监护哮喘等呼吸 病。 欧美国家还制定了标准鼓励和推荐这种无浸入性诊断技术， 对检测精 度与下限的要求不得高于 5 ppb。
本例选用的是一氧化氮电化学气敏元件。 该气敏元件目前广泛用于工 业安全与环境的气体检测。 由于空气或呼气中许多气体、 例如 CO、 CO2、 NO2、 氧气等可以产生 10到 100 ppb范围内的响应贡献， 该气敏元件的检 测下限与精度在 0.1-1 ppm左右。 但在实验室内采用无任何干扰气体的配 气、并严格控制配气温度（22度）与湿度（70%)以及气敏元件的温度（22 度） ， 该气敏元件的检测下限与精度可以达到 5 -10 ppb。
本实施例测试装置参见图 1。 过滤器 6采用的是高锰酸钾等多孔填料 压制而成， 可以过滤一氧化氮到低于 5 ppb的浓度。 气泵 3采用的是市场 上供应的 GminiP型号的国产微型气泵， 18克重， 最大尺寸为 20毫米。 控 制阀是 2与 7是市场上供应的常通式微型两位三通电磁阀。 样品室 5采用 内径为 6毫米、 长度为 70厘米的聚四氟乙烯管， 容量为 20毫升。 各部件 的连接均使用聚四氟乙烯接口与接管。
本实施例利用按图 1形成的传感器测试装置进行了两组实验。 一组是 利用实验室已知浓度的配气进行。 另一组是对志愿者进行呼气检测。 呼气 样品按照欧美 2005年标准推荐的呼气一氧化氮检测程序中的气袋取样获 得。 采用的是市场上供应的有进、 出口阀门控制的 500毫升的聚四氟乙烯 取样袋。 作为对比， 还使用了被称为一氧化氮分析金标的化学发光光谱仪 (美国通用电气仪器， 型号 NOA280 进行了测试。所有检测在室内条件进 行。 本发明测试装置的气体流量为 3毫升 /秒， 全部检测时间为 2分钟。 图 2分别给出了两组结果： 一组是两种测试方法对已知浓度的一氧化氮 （氮 气作为载气） 的检测对比 （上图） ， 另一组是分别对三个呼气样品的检测 结果 （下图， 分别为左右两组三条响应曲线） 。 第一组试验表明在 0 到 300 ppb 的浓度范围内， 本发明的测试装置与化学发光方法均与已知的配 气浓度基本吻合， 两种方法平均值的误差不超过 l ppb， 在化学法光光谱 仪的分辨率与精度之内。 本发明的测试装置可以达到的检测下限与精度为 2-3 ppb, 接近化学发光方法的数值。 比较图 2下图中分别对三个呼气样品 的检测结果可以看出， 本发明的传感器测试装置显示了较高的噪音 （脉 动）。其原因是测量电路电子信号与气路气流状态可能存在的波动的影响。
此外顺便提及根据欧美推荐标准本应用实例图 2表示的诊断意义。 图 2中志愿者 1的呼气浓度 14 ppb NO， 表明无气道炎症问题； 志愿者 2 的 呼气浓度为 23 ppb NO, 表明可能有轻微的气道炎症或者呈现呼吸病的早 期症状； 志愿者 3 的呼气浓度为 44 ppb NO， 表明气道炎症导致的支气管 哮喘 （25-50 ppb 之间） 。 继续升高的呼气一氧化氮浓度预示着更严重的 呼吸病。 应用实施例二
本例用来说明本发明如何检测空气中 ppb量级的甲醛浓度。 环境法规 要求的最高浓度不得高于 80 ppb, 实行检测分析的精度至少 10 ppb。 目前 该项环境检测存在的问题是： 标准的化学分光光度仪与气相色谱仪能满足 分析要求， 但难以携带到现场使用； 而可以携带到现场的传感器检测仪不 能满足分析要求， 只能用于环境污染定性的报警安全监控。
本例选用的是甲醛电化学气敏元件。 如同应用实施例一中的一氧化氮 气敏元件一样， 该气敏元件在严格控制的实验室配气与检测环境下的检测 下限可以达到 10ppb。 但对于通常的室内外空气环境进行实地检测， 可靠 稳定的浓度检测范围则在 100 ppb以上。 目前所有甲醛电化学气敏元件的 另一个显著问题是灵敏度的快速衰减及湿度,温度与干扰气体对气敏元件 响应信号的影响不可忽略。 该实施例表明本发明不仅能够提高检测的灵敏 度与选择性， 而且还能够提高检测的稳定性与可靠性。
本实施例测试装置参见图 1。 本应用实例中仍然采用应用实例一中的 气泵、 样品室、 控制阀与接管设置。 选用的甲醛过滤器为亚硫酸氢钠与碱 石灰混合物构成的多孔材料构成， 能够将甲醛过滤到低于 10 ppb的浓度。 甲醛配气按照国家标准 《公共场所空气中甲醛测定方法》
(GB/T18204.26-2000) 的方法进行。 同时采用该标准描述的气相色谱仪 (Agilent7890) 方法进行分析。 图 3的测试数据以气相色谱分析值作为浓 度标准 （图中横坐标） ， 比较了本发明测试装置在 0-1000ppb 甲醛浓度范 围的测试性能。 可以看出本发明的测试装置基本上接近或达到气相色谱的 分析性能，在试验室条件下能够达到的检测下限与分辨率基本上为 10 ppb。
目前甲醛电化学检测仪的一个突出问题是快速的零点和灵敏度漂移。 本发明的测试装置在这方面的优势更为突出。 例如， 对同一浓度样品进行 连续 7天、 每天同一时间检测一次， 而本发明装置的响应信号累计变化小 于 3%。 随着使用次数的增加， 传统的气体检测仪中电化学气敏元件电极 活性下降结合湿度以及干扰气体的影响， 造成了零点和灵敏度漂移， 需要 频繁及时的标定。 但由于本发明传感器对每次检测都有效的消除了这些影 响， 因此仍然能够保持较高的灵敏度并且不再需要零点校正。 应用实施例三
本例用来说明本发明如何检测环境空气中 ppb范围内的苯蒸汽的浓 度。 环境法规要求的最高浓度不得高于 90 ppb, 实行检测分析的下限与精 度为 10 ppb。 目前仅气相色谱等实验室分析仪器能满足分析要求。 几乎所 有的传感器检测仪由于较差的灵敏度或选择性而尚未用于该项环境检测。
本实施例选用的是发明者自己制备的单壁碳纳米管半导体气敏元件， 由钯铱金属修饰的碳纳米管分散在铂金电极上构成。 在室温下， 该气敏元 件对氮气中苯的检测的线性范围为 100 - 5000ppb。 进一步的实验评价表 明，空气中湿度、氧气与氧化氮浓度的变化对该气敏元件的影响是显著的， 可以造成 10 - 100 ppb量级以及更大的干扰，湿度的影响还使零点或基线严 重漂移。 碳纳米管半导体气敏元件的低选择性、 尤其是对湿度的敏感效应 是许多文献公开报道的显著问题， 也是它们目前还处在试验室开发阶段的 主要原因。 本实施例表明对该问题的一个解决方案。
本实施例测试装置参见图 1。 本应用实例中仍然采用应用实例一中的 气泵、 控制阀与接管设置。 相比于电化学气敏元件， 碳纳米管半导体气敏 元件的响应时间与恢复时间均比较长， 分别接近 30与 60秒。 过滤器填料 为用来吸附苯系有机物的 TENAX气相色谱柱填料， 为 2， 6—二苯基对苯 醚多孔聚合物担体。在室内环境检测标准中，规定使用 TENAX吸附管采集 空气中苯系有机物蒸汽， 然后带回试验室加热脱附后由气相色谱仪确定苯 系有机物含量。
苯蒸汽的配气按照按照国家标准 《空气质量甲苯、 二甲苯、 苯乙烯的 测定气相色谱法》 （GB14677) 进行。 同时， 并采用该标准描述的气相色 谱仪 （Agilent7890) 方法进行分析。 图 4的测试数据以气相色谱分析值作 为浓度标准 （图中横坐标） ， 比较了本发明测试装置在 0-1000ppb 苯浓度 范围的测试性能。 可以看出本发明的测试装置基本上接近或达到气相色谱 的分析性能， 在试验室条件下能够达到的检测下限与分辨率基本上为 10 ppb。 本发明测试装置与气相色谱仪的平均误差 （5ppb左右） 基本上在色 谱仪本身的精度范围之内。 应用实施例四
本例用来说明本发明如何检测呼气中 ppb范围内的丙酮的浓度。 呼气 中丙酮作为一种糖尿病的标志物而一直引起关注， 其浓度高低表明了患病 的程度， 通常糖尿病患者呼气中丙酮的浓度高于 l ppm或 1000 ppb， 而用 来糖尿病早期诊断需要检测的浓度必须远远小于这个数值， 例如达到 100 ppb 的检测下限与 100 ppb 的检测精度。 此外， 丙酮和苯等有机蒸汽也是 法规要求的对接触该类气体的人员进行呼气检测的内容， 规定的检测下限 为 480 ppb。 而这样的要求通常只有试验室分析仪器才能满足。 一些包括 氧化物半导体与光离子化气敏元件可以检测到低浓度的丙酮， 但它们的选 择性极差， 测量的信号包含来自于类似结构或性质的气体几乎量级相同的 贡献， 因此根本不能用于选择性与可靠性要求非常严格的气体尤其是呼气 检测。 本应用实施例表明了一个解决方案。
本实施例选用的单壁碳纳米管半导体气敏元件与实施例三描述的基 本相同。 但是用来修饰碳纳米管的钯铱合金与气敏元件的老化热处理过程 有所不同， 目的是对丙酮获得更高的选择性。该气敏元件在丙酮浓度 0 - 5 ppm (即 5000 ppb) 范围内的电压或电流输出基本是线性的， 湿度与干扰 气体的贡献也是显著的， 湿度的变化引起检测零点或基线的显著漂移。
本实施例的实施也基本与实施例三相同。 除了采用试验室配气方法 外， 还检测了发明者吸入含有丙酮空气后的呼气样品。 检测按照中国卫生 部行业标准《呼出气中丙酮的气相色谱测定方法》（标准号 WS/T175 - 1999) 规定的取样与分析方法进行。 对不采用取样袋的直接的呼气检测， 本实施 例在进气口处设置了过滤呼气中微生物细菌和微粒的过滤器以及适当降 低呼气中饱和湿度、 对水分子吸附的 3A活性炭构成的过滤器。 检测的结 果表明在图 5中。 可以看出， 在试验检测 0-5 ppm的浓度范围内， 气相色 谱和本发明的传感器检测装置对丙酮蒸汽的浓度检测结果是一致的。 两者 之间的平均差异位于气相色谱仪本身具有的精度范围之内。 本实施例的传 感器测试装置的检测下限可以达到 200 ppb或 0.2 ppm。 顺便提及的是图 5 中志愿者呼气的浓度均在 lppm 之下， 表明无糖尿病问题。 通过上面详细描述的具体实施方案与实施应用例， 可以清楚的看出本 发明提供的许多优点。 根据本发明， 目前现有的气敏元件、 气体传感器与 气体检测仪可以极大程度的提高灵敏度与选择性， 接近、 甚至超过包括气 相色谱在内的试验室分析仪器的检测性能， 并且保持了其本身具有的携带 方便、 操作简单的应用特点。 而这种显著、 甚至本质上的改进不仅能够满 足工业环境安全对气体传感器不断提高的检测应用要求外， 还可以使气体 传感器进入例如上面实施应用例描述的生活环境安全与健康检测的应用 领域。
上述实施例是提供给熟悉本领域内的人员来实现或使用本发明的， 熟 悉本领域的人员可在不脱离本发明的发明思想的情况下， 对上述实施例进 行种种修改或变化， 因而本发明的保护范围并不被上述实施例所限， 而应 该是符合权利要求书提到的创新性特征的最大范围。

Claims

权 力 要 求 书
1. 一种高灵敏度与高选择性气体传感器， 其特征在于， 包括：
进气口， 气体样品由此进入传感器；
气泵， 该气泵用来输送所述气体样品；
气敏元件， 该气敏元件对所述气体样品检测， 检测信号主要包括被测 气体的贡献；
过滤器， 该过滤器除去所述气体样品中的被测气体；
样品室： 用于存储部分所述气体样品；
控制阀， 控制所述气体样品的气流方向与压力等流动状态；
出气口， 所述气体样品由此离开传感器。
2. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述气泵、 气敏元件、 样品室、 过滤器和控制阀在进气口与出气口之 间形成循环气路， 对同一气体样品在相同的温度、 湿度、 压力、 气流等条 件下进行两次测量：
一次测量： 气敏元件对含有被测气体的气体样品的测量；
二次测量： 气敏元件对除去被测气体的气体样品的测量；
对被测气体的检测结果是两次测量的差值。
3. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述进气口为气体样品进入传感器的管路、 包括进气过滤器， 用来除 去对传感器中气泵、 控制阀、 样品室、 过滤器、 气敏元件等有损坏或影响 性能的有害物质。 气体样品包括环境气体、 呼吸气体、 工业或机动车辆排 放气体、 工业处理以及加工气体等， 其中的有害物质包括气体微细颗粒、 病毒细菌、 腐蚀性气体以及冷凝水等。
4. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述气泵为微型气泵或其它所有可以驱动气体流动的装置， 优选的气 泵为流量或压力恒定或稳定的装置， 该装置的材质是惰性的， 对被测气体 无任何吸附与反应。
5. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述气敏元件为电化学、 半导体、 催化燃烧、 光学、 热导等气体检测 元件，主要对被测气体响应，但检测的信号可能包括环境或气体样品温度、 湿度、 压力、 气流以及干扰气体的次要贡献； 优选的气敏元件为电信号输 出的电化学与半导体气敏元件。
6. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述过滤器用来去除被测气体， 去除的效率保证其残余量不足以引起 气敏元件可检测的信号； 也允许去除其它对气敏元件无信号贡献的气体； 优选的过滤器由固态或液态的吸附剂或催化剂构成； 如果被测气体在气敏 元件中通过反应或吸附所消耗， 所述过滤器可以省去。
7. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述样品室用来存储所述部分气体样品,其内部与气体样品接触的材 料对被测气体无任何化学或物理作用， 包括各类化学反应和吸附过程； 其 结构优选为能够避免气体沿流动方向混合的活塞流装置， 包括细长管道、 设有挡板的流动装置、 列管流动装置或者所述传感器内部的所有气体空 间。
8. 如权利要求 1所述的高灵敏度与高选择性气体传感器， 其特征在于， 所述控制阀用来控制气流方向， 包括各种类型的气体阀， 优选的是可 以自动控制的微型电磁阀， 包括单向阀、 二通阀、 三通阀、 四通阀与它们 之间等效的组合。
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CN116870678B (zh) * 2023-09-01 2024-01-16 武汉怡特环保科技有限公司 一种气体冷凝捕集监测调控方法和装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6636811B1 (en) * 1998-02-24 2003-10-21 Wma Airsense Analysentechnik Gmbh Method and device for identifying gaseous compounds
JP2004020436A (ja) * 2002-06-18 2004-01-22 New Cosmos Electric Corp フィルター出し入れ装置
US6862915B2 (en) * 2003-03-20 2005-03-08 Rosemount Analytical Inc. Oxygen analyzer with enhanced calibration and blow-back
CN101368921A (zh) * 2008-09-08 2009-02-18 无锡尚沃生物科技有限公司 高灵敏度与高选择性气体传感器

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN200968942Y (zh) * 2006-11-07 2007-10-31 王保齐 气体自动采集、监测装置
CN101000318A (zh) * 2006-12-28 2007-07-18 中国科学院合肥物质科学研究院 基于温度控制的传感器阵列及气体检测方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6636811B1 (en) * 1998-02-24 2003-10-21 Wma Airsense Analysentechnik Gmbh Method and device for identifying gaseous compounds
JP2004020436A (ja) * 2002-06-18 2004-01-22 New Cosmos Electric Corp フィルター出し入れ装置
US6862915B2 (en) * 2003-03-20 2005-03-08 Rosemount Analytical Inc. Oxygen analyzer with enhanced calibration and blow-back
CN101368921A (zh) * 2008-09-08 2009-02-18 无锡尚沃生物科技有限公司 高灵敏度与高选择性气体传感器

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102706948A (zh) * 2012-06-21 2012-10-03 尚沃医疗电子无锡有限公司 一种利用电化学传感器测量气体浓度的方法与装置
JP2014139563A (ja) * 2012-12-18 2014-07-31 Daiki Rika Kogyo Kk 濃度測定装置
EP2746763A3 (en) * 2012-12-18 2015-09-30 Daiki Rika Kogyo Co., Ltd Gas concentration measuring device
US9170247B2 (en) 2012-12-18 2015-10-27 Daiki Rika Kogyo Co., Ltd. Concentration measuring device
CN108120691A (zh) * 2016-11-29 2018-06-05 上海安杰环保科技股份有限公司 气相分子吸收光谱仪
CN106546547A (zh) * 2016-12-09 2017-03-29 北京东方安杰科技有限公司 一种基于传感器并使用渗水吸收干燥装置的气相分子吸收光谱仪
US11280705B2 (en) * 2016-12-23 2022-03-22 Koninklijke Philips N.V. System and method for measuring a concentration of a pollutant within a gas
CN108007925A (zh) * 2017-11-16 2018-05-08 国网福建省电力有限公司泉州供电公司 Sf6气体分解物比色法检测仪
CN110412089A (zh) * 2019-08-22 2019-11-05 北京知几未来医疗科技有限公司 一种基于TiO2纳米敏感材料的气敏传感器、制备方法及呼气检测装置
WO2021123864A1 (en) * 2019-12-16 2021-06-24 Aeroqual Ltd. Improved measurement of gases
GB2606062A (en) * 2019-12-16 2022-10-26 Aeroqual Ltd Improved measurement of gases
GB2606062B (en) * 2019-12-16 2024-01-17 Aeroqual Ltd Improved measurement of gases
US20220018822A1 (en) * 2020-07-17 2022-01-20 International Business Machines Corporation Protective enclosure for gas sensors
US11624740B2 (en) * 2020-07-17 2023-04-11 International Business Machines Corporation Protective enclosure for gas sensors
CN113358719A (zh) * 2021-06-07 2021-09-07 深圳市中志环境科技有限公司 一种多参数气体恒温监测装置及网格化空气质量监测系统

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