非分光红外气体传感器研究进展

介绍了非分光红外气体传感器的工作原理,将非分光红外传感器与常用气体传感器进行了对比分析。综述了非分光红外技术在光源设计、气室设计、探测器设计、信号处理及自组装多气体探测系统等关键技术的研究进展,为进一步提高气体检测精度和响应提供了研究方向。提出了非分光红外气体传感器要朝着小体积、多功能集成、满足复杂应用环境的方向发展。     

基于GWO-BP神经网络补偿的SF6红外气体传感器

为实现电力系统中SF 6气体的有效监测与控制,本文基于非色散红外原理(NDIR),设计了一种SF 6气体传感器。但是,在实际的测量中,环境的温度与气压差异性容易影响SF 6气体浓度检测装置的检测精度,因此需要采取适当的方法消除环境引起的测量误差。本文采用灰狼智能优化算法—误差反向传播(GWO-BP)神经网络对环境温度与气压变化引起的测量误差进行了补偿,并与其他补偿方法作了比较。分析得出:进行补偿后的浓度数据在0~2000 ppm范围内误差为±15 ppm,满量程误差为0.75%FS,有效提升了传感器的测量精度与稳定性。相较于电路补偿法,该方法有更高的测量精度,并且降低了传感器的体积和成本。     

基于非分散红外法的二氧化碳浓度检测综述

二氧化碳(CO₂)是温室气体的重要组分之一,实时检测其浓度变化对缓解温室效应等方面具有非常重要的意义。非分散红外(Non-dispersion infrared, NDIR)法具有稳定性好、响应速度快、测量范围宽等优点,广泛应用于便携式气体检测等领域。首先分析了NDIR法应用在CO₂检测领域的优点,并对NDIR检测原理进行了简单的概述。然后对NDIR气体分析仪的基本结构进行了详细阐述,并对测量系统的经典气体标定方法进行了综述。最后综合分析了NDIR的特点,并展望了未来的发展趋势。     

具有温度补偿的非分光红外CO2传感器设计

近年来,温室效应愈发明显,环境二氧化碳（CO₂）浓度增加带来的副作用严重影响了人们的生产生活。目前,商业化的CO₂传感器体积较大,便携化、高精度、模块化等方面不尽人意,设计了一种基于热释电的非分光红外法（NDIR） CO₂浓度测量系统,主要分为气室结构设计、信号电路设计、软件控制设计与数据处理四个部分。气室结构设计方面采用单通道结构设计,并对气室进行了光学仿真,最终确定了气室的尺寸,有效提高了系统的测量精度。信号电路设计方面设计了一种基于差分方式的小信号放大电路,将有效信号从噪声中提取并放大,提高分辨率。软件控制设计方面应用数字滤波算法,滤除干扰与杂波,提取数据中的有效值,提高信噪比。数据处理方面,搭建CO₂气体测试平台,通过温湿度与峰峰值补偿公式补偿温度对峰峰值产生的影响,再使用25 ℃下曲线拟合法计算气体浓度值,最终通过串口输出。经过测试,该系统测量范围为5%,相对误差值在1500 ppm以内,能够满足防火报警、矿下监测等场合的安全测试需求。     

影响全天域光轴平行度检测精度因素分析

为提高红外甲烷传感器的精度,对气室结构、电路和数据处理进行了优化设计。通过实验和光学仿真对红外气体传感器气室结构进行了重新优化设计,确定了最佳尺寸;采用三级差动放大电路设计滤除噪声;在数据处理的算法上,选用二次插值查表法来拟合方程处理数据等一系列举措设计出新的红外甲烷传感器。在甲烷浓度为0%~3%的体积分数段内对传感器进行随机测试,新传感器的反应时间能够控制在20 s以内,探测器灵敏度得到提高,测量误差控制在0.04%。与国内外相似的产品相比,优化的传感器在高灵敏度、测量误差和反应时间上都达到了较高水平。     

微型化FAIMS气体传感器的制备与测试

依据高场非对称波形离子迁移谱(FAIMS)原理,设计了一种迁移区和收集区一体化式的微型化FAIMS气体传感器。电离区采用能量为10.6eV的紫外灯对异丁烯气体进行电离,迁移区和收集区采用微电子机械系统(MEMS)工艺进行制备,将图形化后的硅片和硼硅玻璃通过阳极键合工艺制备成一体化的传感器,传感器尺寸为3mm×4mm×1mm。实验中,搭建了相应的测试系统,在收集区外接放大电路对异丁烯的电离进行了检测。将传感器在不同体积分数异丁烯环境中进行测试。测试结果表明,传感器测试精度可达1×10^-7/mV,在体积分数2×10^-4的异丁烯环境中其响应时间为6s,恢复时间为7s,具有较快的响应时间和恢复时间,且具有良好的稳定性和重复性。     

用于机动车尾气检测的NDIR传感器的加权定标方法研究

非分散红外（NDIR）气体传感器是机动车尾气CO和CO2检测系统的核心部件,一般使用定标的方法来计算待测气体的浓度。针对传统定标方法生成的定标曲线在低于CO和CO2满量程10%范围内的拟合优度不能满足实际使用要求的问题,提出了一种基于最小二乘加权拟合法的定标方法,通过对低浓度点赋予更大的权重和增加定标点的数目来改善定标曲线在低浓度范围内的拟合优度。采用该方法的定标结果表明,定标曲线在整个量程范围内的定标误差均小于2%。所提出的定标方法具有较高的应用价值。     

基于对称悬臂梁的小型化低频FBG加速度传感器研究

提出了一种基于对称悬臂梁的小型化低频光纤布拉格光栅(FBG)加速度传感器。首先根据传感器结构的力学模型,推导出传感器的灵敏度和固有频率表达式;然后对传感器进行结构参数优化,采用ANSYS Workbench对传感器进行静应力与模态分析;最后根据分析结果制作传感器,并实验研究了传感器的幅频响应、灵敏度特性、横向抗干扰能力和冲击响应。结果表明,该传感器固有频率为72 Hz,灵敏度为681.7 pm/g,抗横向干扰度小于4.9%,且体积仅为6.48 cm^(3),可用于50 Hz以下的低频微弱振动信号的实时监测。     

一种提高气敏元件热稳定性的优化设计

本文提出一种新的具有较好热稳定性的气敏元件结构。在这种结构里,气敏元件的输出无需外接取样电阻即可获得。文中对现有气敏元件和新型结构气敏元件的热稳定性作了理论分析和实验对比。本设计也适用于其它类型半导体气敏元件。     

Semiconductor‐Type MEMS Gas Sensor for Real‐Time Environmental Monitoring Applications

Low power consuming and highly responsive semiconductor‐type microelectromechanical systems (MEMS) gas sensors are fabricated for real‐time environmental monitoring applications. This subsystem is developed using a gas sensor module, a Bluetooth module, and a personal digital assistant (PDA) phone. The gas sensor module consists of a NO₂ or CO gas sensor and signal processing chips. The MEMS gas sensor is composed of a microheater, a sensing electrode, and sensing material. Metal oxide nanopowder is drop‐coated onto a substrate using a microheater and integrated into the gas sensor module. The change in resistance of the metal oxide nanopowder from exposure to oxidizing or deoxidizing gases is utilized as the principle mechanism of this gas sensor operation. The variation detected in the gas sensor module is transferred to the PDA phone by way of the Bluetooth module.     

Rapidly Modulated Wide-Spectrum Infrared Source Made of Super Aligned Carbon Nanotube Film for Greenhouse Gas Monitoring

Non-dispersive infrared (NDIR) gas monitoring has advantages of environment stability, convenient operation and maintenance, wide detection range, and multi-gas-detection capability. However, the conventional IR sources for NDIR gas monitoring, such as miniature lamps, microelectromechanical system (MEMS) light sources, and light-emitting diodes (LEDs), can only work at narrow modulation frequency and spectral range, or require complicated design and fabrication, because of the constraint of materials and work principle. These issues cause low data acquisition rate, poor anti-interference ability and limited gas compatibility to NDIR. Here, the super-aligned carbon nanotube (SACNT) film is developed as an IR source in NDIR gas monitoring system. It has a wide spectral range (0.2–334 µm), a facile fabrication method, and can work up to a high frequency ≈150 kHz. A mechanical-chopper-free and wide-concentration-range monitoring equipment for CO₂ and CH₄ greenhouse gases is demonstrated with SACNT film IR source. The concentration ranges for CO₂ and CH₄ investigated in this paper are 0.0195–20.10% (v/v) and 0.10–17.11% (v/v), respectively. It can be easily applied to monitor other kinds of gases as well.     

Zn/Co金属有机框架的制备及其对正丁醇的气敏特性

采用水热法合成了Co3O4、ZnO和Zn/Co金属有机框架(Zn/Co-MOF)纳米结构。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对其形貌和晶体结构进行了表征,分析结果表明制备的Zn/Co-MOF为边长约300 nm的立方体结构。制备了基于Co3O4、ZnO和Zn/Co-MOF纳米结构的气体传感器,并对正丁醇进行了气敏性能研究。实验结果表明:三种气体传感器对正丁醇均有明显的响应,其中Zn/Co-MOF气体传感器的气敏性能最优。Zn/Co-MOF气体传感器最佳工作温度为200℃,其对体积分数为1×10^-4正丁醇气体的灵敏度为59.18,响应/恢复时间分别约为39 s和40 s。同时,Zn/Co-MOF传感器还具有良好的选择性、重复性和长期稳定性。     

A Self-Powered,Rechargeable, and Wearable Hydrogel Patch for Wireless Gas Detection with Extraordinary Performance

Flexible gas sensors play an indispensable role in diverse applications spanning from environmental monitoring to portable medical electronics. Full wearable gas monitoring system requires the collaborative support of high-performance sensors and miniaturized circuit module, whereas the realization of low power consumption and sustainable measurement is challenging. Here, a self-powered and reusable all-in-one NO₂ sensor is proposed by structurally and functionally coupling the sensor to the battery, with ultrahigh sensitivity (1.92%/ppb), linearity (R² = 0.999), ultralow theoretical detection limit (0.1 ppb), and humidity immunity. This can be attributed to the regulation of the gas reaction route at the molecular level. The addition of amphiphilic zinc trifluoromethanesulfonate (Zn(OTf)₂) enables the H₂O-poor inner Helmholtz layer to be constructed at the electrode–gel interface, thereby facilitating the direct charge transfer process of NO₂ here. The device is then combined with a well-designed miniaturized low-power circuit module with signal conditioning, processing and wireless transmission functions, which can be used as wearable electronics to realize early and remote warning of gas leakage. This study demonstrates a promising way to design a self-powered, sustainable, and flexible gas sensor with high performance and its corresponding wireless sensing system, providing new insight into the all-in-one system of gas detection.     

一种冰醋酸红外气体传感器设计

提出了一种基于非色散红外原 理的冰醋酸红外气体传感器。介绍了冰醋酸红外气体传 感器的原理,然后对其结构设计进行了详细描述,并利用Light Tools 软件对其光路进行了仿真验证,最后获得了冰醋酸红外 气体传感器样机。测试结果表明,该传感器在0～5000 ppm范围内 的测量精度优于±1%F.S.,响应时间(T90)为29 s。这种传感器的光源部分 采用电调制方式,舍弃了传统的红外气体传感器光源部分的机 械斩波结构,进而减小了传感器的体积,提高了稳定性。因此,该传感器 在冰醋酸运输、储存和使用等领域具有广泛的应用前景。     

Design, fabrication and characterization of pyroelectric thin film and its application for infrared gas sensors

Prepared by a sol-gel process, the lead zirconate titanate (PZT) (PbZr_0.3Ti_0.7O₃) thin film, which is chosen as an infrared sensing film, uses lead acetate trihydrate, zirconium acetylacetone, acetylacetone, and titanium isopropoxide as starting materials. The pyroelectric infrared sensor with the PZT thin film has been successfully fabricated. The fabrication process of the device is discussed in detail. A new Au Pt-PZT-Pt infrared detecting structure on silicon substrate with a micro bridge is designed. Under the response and reference dual-element configuration, undesirable signals, caused by vibration, ambient temperature change, and sunlight, are cancelled out at the input of the preamplifier circuit. The dual-element structural design of the device is discussed and analyzed in detail. In order to realize our purpose to use this detector to monitor gas concentration, we designed a detection set-up in the light of a certain gas which absorbs infrared radiation at specific wavelengths. The gas concentration is obtained by designing a weak signal detect circuit and data arithmetic. The first measurement for methane is reported. Experimental result shows the ability of methane detection of the detector based on the infrared sensor element.     

CO2 detection with CNx thin films deposited on porous silicon

In recent years, porous silicon (PSi) has attracted a great deal of attention for sensing applications. However, the high reactivity of PSi surfaces causes serious problems of stability. In this work, we developed new thin films that can serve as stabilizer of PSi for CO₂ gas sensors development. PSi surface was coated with carbon nitride (CN_x) film which is one of the most important interfering to stabilize the PSi layer. CN_x film was deposited by pulsed laser ablation. The effect of CO₂ gas on the sensor response was investigated for different polarization voltages. The electrical properties of (Al/CN_x/PSi/Si) structure were modified in the presence of the gas. The device shows a high sensitivity against CO₂ gas. Furthermore, the current variation of the sensor as a function of time has been investigated. The results show that the Al/CN_x/PSi/Si structure becomes stable after the first two weeks.     

肌肉注射维生素B12缓解食欲不振1例

论述了气体摆的机理,分析了密闭腔中自然对流气体的浮升力及浮升力与温度变化的关系式.该文给出了二维微机械气体摆式加速度计与倾角传感器的结构原理和信号处理电路,并通过对实际制作的两维微机械气体摆式加速度计和倾角传感器样机进行测试.结果表明,在±7 g和±25°时,两维微机械加速度计和微机械倾角传感器的非线性度均小于1%FS.     

二氧化锡/多孔硅/硅光伏特性研究

测量了二氧化锡（SnO2）／多孔硅（PS）／硅（Si）的光电压谱，分析表明：在SnO2／PS／Si材料中存在着两个异质结；当样品吸附还原性气体时，其光电压明显下降。当样品在1％液化石油气的氛围时（相对于空气），光电压减少了16．4％-27．5％；在1％CO氛围时，减少了8．1％-19．4％；在1％H2氛围时，减少了12．1％-14．9％，因此SnO2／PS／Si可作为一种新的敏感元件。文中还对测量结果进行了讨论分析。     

用于氨氮检测的三维微纳氨气传感芯片及系统研究

该文设计并制备了一种多层微结构的安培型氨气三维微纳传感芯片,并构建了以此微传感芯片为敏感单元的氨氮检测系统,探索了使用安培型氨气微传感器检测氨氮的方法。该微传感芯片采用微纳加工工艺制备,使用聚合物键合工艺在较低温度下实现了微传感器多层结构的封装。使用纳米铱作为传感器的敏感材料,其具有良好的电催化氧化能力,可使传感器具有较高的灵敏度。对Ag/AgCl微参比电极的稳定性进行了考察。使用自行设计的氨氮检测系统对氨氮样品进行检测,对微传感器的时间响应特性、浓度响应特性、重复性及选择性进行了测试和分析。实验结果表明,在0.5~10 mg/L的测试范围内,检测电流与氨氮浓度保持良好的线性,灵敏度为1.62 A/(mg/L),线性相关系数为0.995,重复性偏差为5.73%。同时,传感器显示出良好的选择性。     

气体摆式水平姿态传感器的结构及信号处理

研究了气体摆式水平姿态传感器的工作原理、结构、信号获取电路及补偿技术。采用铂电阻丝作为热源,在密闭腔中使气体产生自然对流,用硬件电路和数字化软件补偿技术提取载体姿态信号并进行处理。研制出测量范围为±45°,非线性度小于1%FS,分辨率小于0.01°的气体摆式水平姿态传感器。