基于硅悬臂梁谐振器的新型气体传感器

研究了一种基于硅悬臂梁谐振器的新型气体传感器.该传感器在敏感环境中,可同时获得敏感膜电导率和质量变化,测量被测气体分子的荷质比,具有高灵敏度和高选择性.根据这一原理,针对气体传感器的需求,设计了硅悬臂梁谐振器化学传感器结构,进行了仿真优化,并采用MEMS表面牺牲层工艺制备该器件,激光频率仪测量验证了该微型谐振梁的谐振频率.     

一种半岛型结构谐振梁压力传感器

提出了一种新型结构压力传感器 ,器件由上下两硅片键合而成 ,上硅片制作半岛型结构氮化硅谐振梁 ,下硅片制作矩形压力膜。应用有限元软件对器件结构及灵敏度进行了计算机模拟分析 ,器件利用MEMS技术研制并采用电热激励压阻拾振方式进行了测试。实验及理论模拟分析结果证实新型结构可以大大提高压力传感器灵敏度     

电磁激励微谐振式传感器的设计与制作

利用微电子机械加工技术成功研制出电磁激励-电磁拾振硅谐振梁式压力传感器。传感器以"H"型双端固支梁为谐振器,采用差分检测结构。工艺制作采用体硅加工工艺,并且采用一种减小封装应力的结构完成压力传感器的真空密封及封装。利用锁相环微弱信号检测技术建立的开环频率特性测试系统及闭环自激测试系统测试了传感器的频率、压力特性等相关技术指标。谐振器在空气中的品质因素Q值大于1200;在真空中的Q值大于7000。压力满量程刻度为0～120kPa。差分输出的结果优于单个谐振梁的输出结果,差分输出结果的线性相关系数为0.9999,灵敏度为225.77Hz/kPa。     

Columnar shaped microresonators for mass detection and gas analysis

In this paper miniaturized silicon columns mounted perpendicular to a surface are presented as microresonators for the detection of an exceedingly small mass. In a first sensor design the column resides on a rigid silicon substrate and is forced to oscillate in the first flexural eigenmode. Mass sensitivity was investigated loading a single latex sphere on the top surface of the column and detecting the frequency shift of the resonant frequency. Oscillation was monitored using the optical beam deflection method, focusing a laser beam at the same surface. However, optical readout was substantially hampered by scattering of the laser beam at the loaded particles and diffraction at the column surface. In a second optimized design a silicon column was mounted on a flexible silicon nitride membrane. In this way the optical readout was applied from the flip side of the membrane completely separating the load area and the optical beam path. A proof of principal is given for the optimized sensor design investigating the influence of pure gases on the extrinsic damping behavior of the membrane columnar oscillator.     

振梁式负压传感器

对负压力的测量可采用各种真空计或者负压传感器，但其输出量大多为非电量或模拟式电量，本文制作了一种电热激励的微悬臂梁谐振式负压传感器，它利用随微悬臂梁振动的气体分子等效于增加微梁惯性质量的原理测量气压或气体密度，利用Navier-Stokes方程和连续性方程计算作用在微悬臂梁上的惯性阻力，进而计算出谐振器谐振频率与气压的关系，分析表明，增大梁的宽度，减小梁的厚度和长度可提高传感器的灵敏度。     

Working mechanism of a SiC nanotube NO_2 gas sensor

The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO_2 gas sensor system is established based on an (8, 0) silicon carbide nanotube (SiCNT) with a NO_2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory (DFT) with the non-equilibrium Green's function (NEGF). The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO_2 gas.     

Silicon Carbide-Based Remote Wireless Optical Pressure Sensor

Proposed is a silicon carbide (SiC) weak-lensing-effect-based wireless optical sensor that allows safe, repeatable, and accurate pressure measurement suitable for harsh environments. This completely passive front-end sensor design uses a remoted free-space optical beam that targets a single crystal SiC chip fitted as an optical window within a pressure capsule. With increasing differential capsule pressure, the SiC chip forms a weak convex mirror with a changing focal length. By monitoring the chip reflected light beam magnification, pressure in the capsule is determined. Using a 633-nm wavelength laser beam, the proposed sensor is experimentally tested at room temperature for 0- to 600-psi (0-41atm) differential pressures and a remoting distance of 2.5 m     

光谱式MEMS/CMOS兼容气敏传感器

光谱技术是化学分析的终极手段. 将光谱技术与MEMS (micro-electro-mechanical systems）和CMOS技术结合是解决当前气敏传感器灵敏度低、选择性差、体积大、功耗高、不便于阵列化和高度集成以至于无梯度立体矢量探测能力等问题的有效手段. 本文介绍了一种制作于（110）硅片上的集成光谱式MEMS/CMOS兼容气敏传感器,详述了该气敏传感器的工作原理、传感器结构和制造工艺.     

Integrated silicon anemometer

At present, planar silicon technology allows one to construct very sophisticated integrated circuits for the processing of electronic signals. In the letter, an integrated silicon sensor for the measurement of gas flow is introduced.     

A gas chromatographic air analyzer fabricated on a silicon wafer

A miniature gas analysis system has been built based on the principles of gas chromatography (GC). The major components are fabricated in silicon using photolithography and chemical etching techniques, which allows size reductions of nearly three orders of magnitude compared to conventional laboratory instruments. The chromatography system consists of a sample injection valve and a 1.5-m-long separating capillary column, which are fabricated on a substrate silicon wafer. The output thermal conductivity detector is separately batch fabricated and integrably mounted on the substrate wafer. The theory of gas chromatography has been used to optimize the performance of the sensor so that separations of gaseous hydrocarbon mixtures are performed in less than 10 s. The system is expected to find application in the areas of portable ambient air quality monitors, implanted biological experiments, and planetary probes.     

Nano-WO3 film modified macro-porous silicon（MPS） gas sensor

We prepared macro-porous silicon（MPS） by electrochemical corrosion in a double-tank cell on the surface of single-crystalline P-type silicon.Then,nano-WO₃ films were deposited on MPS layers by DC facing target reactive magnetron sputtering.The morphologies of the MPS and WO₃/MPS samples were investigated by using a field emission scanning electron microscope.The crystallization of WO₃ and the valence of the W in the WO₃/MPS sample were characterized by X-ray diffraction and X-ray photoelectron spectroscopy,respectively. The gas sensing properties of MPS and WO₃/MPS gas sensors were thoroughly measured at room temperature. It can be concluded that:the WO₃/MPS gas sensor shows the gas sensing properties of a P-type semiconductor gas sensor.The WO₃/MPS gas sensor exhibits good recovery characteristics and repeatability to 1 ppm NO₂.The addition of WO₃ can enhance the sensitivity of MPS to NO₂.The long-term stability of a WO₃/MPS gas sensor is better than that of an MPS gas sensor.The sensitivity of the WO₃/MPS gas sensor to NO₂ is higher than that to NH₃ and C₂H₅OH.The selectivity of the MPS to NO₂ is modified by deposited nano-WO₃ film.     

An ammonia gas sensor with two chambers based on U-bending microring resonator

A compact ammonia gas sensor with two gas chambers is proposed in this paper,whose core sensing device is a U-bending microring resonator.The waveguides of ring part and feedback part in this resonator are made of silicon on insulator(SOI) ridge waveguide covered with ZnO nanocrystals which are sensitive to ammonia gas.The sensor can measure two groups of gas samples simultaneously.By computer simulation,we obtain the clear sensitivity curves of two gas chambers in ammonia sensor when the gas concentration increases from 0 to 4‰.The gas concentrations in two chambers can be obtained from one output spectrum,which significantly reduces the material and time consumption.     

硅热流量传感器封装的热模拟分析

针对硅热流量传感器的封装,给出了其一维简化理论模型,并采用有限元分析工具ANSYS/FLOTRAN,建立了该封装结构的热模型．模拟结果显示,该封装后的传感器的温度场与未封装传感器相似,证明陶瓷封装结构是可行的;同时比较了封装前后传感器性能的差异,并进一步分析了传感器的热性能和其特征尺寸的关系．该模型的建立,可以减少大量的模拟分析过程,减小计算量,研究结果将为该传感器封装的进一步优化设计提供理论参考和依据．     

A monolithic gas flow sensor with polyimide as thermal insulator

A novel small monolithic gas flow sensor has been designed and fabricated by use of micromachining of silicon. Its operation is based on the cooling of an electrically heated mass by the gas flow, and detection of the mass's temperature by a diode. The small size, 0.4 mm by 0.3 mm by 30 µm, of the hot part of the sensor gives a fast thermal response (time constant 50 ms). By using polyimide as a thermal insulator a high gas flow sensitivity is achieved, The shape of the sensor will present very little obstruction to the gas flow and also makes it easy to mount.     

超微粒SnO2薄膜元件气敏特性研究

用射频磁控反应溅射法在Si基片上沉积SnO2超微粒薄膜,借集成电路技术制成气敏元件,并用RQ—1型气敏特性测试仪在动态配气系统中测试其气敏特性。结果表明:烧结体SnO2元件的气敏效应出现在300℃以上,而该元件的气敏效应则出现在90℃以下,有利于降低功耗;在80~90℃时,该元件对H2的灵敏度比C2H5OH和CH4高出2~3个数量级,对CO和LPG几乎不敏感。因此可用作在低温条件下工作的薄膜化、集成化、高性能的H2传感器。     

Cryogenic Temperature Measurement Using Silicon Carbide-Based Wireless Optical Sensor

Demonstrated is a novel silicon carbide (SiC)-based wireless optical sensor for cryogenic temperatures. The proposed design uses two wavelength processing and free-space optical beam interrogation of a remoted single crystal SiC chip placed in the cryogenic vacuum chamber to enable wireless temperature measurement. Experimental temperature sensing using the proposed sensor is reported from near room temperature to 100 K with an estimated 0.2 K resolution. The sensor uses eye safe laser wavelengths at 1550 and 1540 nm to implement the signal processing to determine the temperature value     

Thin-Film Bulk-Acoustic-Resonator Gas Sensor Functionalized With a Nanocomposite Langmuir–Blodgett Layer of Carbon Nanotubes

A thin-film bulk acoustic resonator (TFBAR) based on a vibrating membrane of AlN/Si₃N₄ has been fabricated onto a silicon substrate and functionally characterized as gas sensor at a resonating frequency of 1.045 GHz. This novel TFBAR-based gas sensor has been functionalized by a sensing nanocomposite layer, prepared by a Langmuir-Blodgett (LB) technique, of single-walled carbon nanotubes (SWCNTs) embedded in a host matrix of organic material of cadmium arachidate. High-performance gas detection at room temperature of a SWCNT-coated TFBAR sensor has been reported. The sensing device exhibits high sensitivity (e.g., acetone: 12 kHz/ppm; ethylacetate: 17.3 kHz/ppm), fast response (within 2-3 min), slow reversibility (within 1 h), and good repeatability (les 5% variation) of response toward tested organic vapors of acetone, ethylacetate, and toluene.     

SOI CMOS‐Based Smart Gas Sensor System for Ubiquitous Sensor Networks

This paper proposes a compact, energy‐efficient, and smart gas sensor platform technology for ubiquitous sensor network (USN) applications. The compact design of the platform is realized by employing silicon‐on‐insulator (SOI) technology. The sensing element is fully integrated with SOI CMOS circuits for signal processing and communication. Also, the micro‐hotplate operates at high temperatures with extremely low power consumption, which is important for USN applications. ZnO nanowires are synthesized onto the micro‐hotplate by a simple hydrothermal process and are patterned by a lift‐off to form the gas sensor. The sensor was operated at 200°C and showed a good response to 100 ppb NO₂ gas.     

高性能Si基MOS肖特基二极管式氢气传感器研究

报道了采用NO直接氧化制备氮化氧化物作为绝缘层制备高性能Si基MOS肖特基二极管式气体传感器(SDS)的技术。实验结果显示，MOS肖特基二极管式气体传感器具有高的响应灵敏度和好的响应重复性，可以探测浓度约为10^-6的氢气。因此，采用NO直接氧化法制备绝缘层是一种制备高可靠、高灵敏度Si基MOS SDS的技术。     

纳米氧化钨薄膜改性的大孔硅气敏传感器

通过双槽电化学腐蚀法在P型单晶硅表面制备了大孔硅。然后通过直流对靶反应磁控溅射法在大孔硅表面淀积了纳米氧化钨薄膜。使用场发射扫描电子显微镜（FESEM）观察大孔硅和氧化钨/大孔硅样品的形貌。分别使用X射线衍射（XRD）图谱和X射线光电子能谱（XPS）分析氧化钨晶体结构和钨的化合价。在室温下测试大孔硅和氧化钨/大孔硅气敏传感器的气敏特性。结果表明：氧化钨/大孔硅气敏传感器表现出了P型半导体气敏传感器的气敏特性。它对1ppm的二氧化氮显示了良好的恢复特性和重复性。氧化钨/大孔硅气敏传感器的长期稳定性要好于大孔硅气敏传感器。氧化钨的添加提高了大孔硅气敏传感器对二氧化氮的灵敏度。氧化钨/大孔硅气敏传感器对于二氧化氮的灵敏度要高于其对氨气和乙醇的灵敏度。通过淀积纳米氧化钨薄膜,改善了大孔硅对二氧化氮的选择性。