基于薄膜体声波谐振器的免疫球蛋白传感器制备

研制了一种基于薄膜体声波谐振器（ FBAR）的生物免疫球蛋白传感器,该FBAR采用AlN作为压电层,3对Ti/W金属层作为布拉格声学反射层,工作频率为2.047 GHz,回波损耗为－32 dB。利用自组装膜法修饰顶部金电极敏感区域。测试了免疫球蛋白G抗体和抗原的特异性结合前后传感器的指标变化。结果得到传感器的Q值和灵敏度分别达到846,3.38 kHz·cm2/ng,远高于广泛使用的石英晶体微天平（ QCM）,具有广阔的应用前景。     

Thin polymer film based rapid surface acoustic wave humidity sensors

Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption-desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO₃ SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5-95% (recovery time - 2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.     

Highly sensitive mass sensor using film bulk acoustic resonator

Film bulk acoustic resonators (FBAR) have recently been adopted as alternatives to surface acoustic wave (SAW) in high frequency devices, due to their inherent advantages, such as low insertion loss, high power handling capability and small size. FBAR device can also be one of the standard components as mass sensor applications. FBAR sensors have high sensitivity, good linearity, low hysteresis and wide adaptability. In this study, a highly sensitive mass sensor using film bulk acoustic resonator was developed. The device structure of FBAR is simulated and designed by the Mason model, and fabricated using micro electromechanical systems (MEMS) processes. The fabricated FBAR sensor exhibits a resonant frequency of 2442.188 MHz, measured using an HP8720 network analyzer and a CASCADE probe station. Experimental results indicate that the mass loading effects agree with the simulated ones. Results of this study demonstrate that the sensitivity of the device can be achieved as high as 3654 Hz cm²/ng.     

High-resolution high-voltage sensor based on SAW

A surface acoustic wave (SAW)-based high-voltage sensor is described. The sensor consists of a SAW oscillator fabricated on a 10 mm × 10 mm 128° rotated Y-cut, X-propagating LiNbO₃ substrate. The voltage is applied to electrodes on the substrate, and the resulting electric field changes the propagation time of the SAW. The propagation time is directly related to the output frequency of the SAW oscillator. The high-voltage sensor offers a small-sized high-voltage measurement device with several attractive features: a high resolution (better than 0.2 V up to 2.4 kV, better than 0.4 V for higher voltages), a large range (−10 to +10 kV), a high input impedance (> 10¹³ ω) and a low input capacitance (< 10 pF). The sensitivity amounts to 16 Hz V⁻¹.     

新型体声波传感器读出电路的实验验证

为了实验验证此前通过仿真验证的基于六端口反射计的新型BAW传感器读出电路的方案的可行性,本文制作了新型BAW传感器读出电路并对其进行了测试.以串联谐振频率约为1.5 GHz的薄膜体声波谐振器(FBAR)为待测器件(DUT),设计、制作了一种能够满足该FBAR谐振频率测量带宽(1.3 GHz~1.7 GHz)要求的PCB上微带六端口网络和检波器,配合射频信号发生器和示波器,获得了模拟DUT(50ΩSMA匹配负载)的反射系数-频率(Γ-f)曲线测量结果.与矢量网络分析仪(VNA)的测量结果进行了对比,两者吻合较好,实验验证了"基于六端口反射计的BAW传感器读出电路"可用于FBAR谐振频率的测量.本文工作对实用化BAW传感器的研制和片上矢量网络分析仪(VNA-on-Chip)的设计都有借鉴意义.     

The effects of temperature, relative humidity and reducing gases on the ultraviolet response of ZnO based film bulk acoustic-wave resonator

This study investigated the influence of temperature, relative humidity and reducing gases on the ultraviolet (UV) response of ZnO based film bulk acoustic-wave resonator (FBAR). As temperature increased, the UV response of the FBAR degraded. This was attributed to the softening of the ZnO film with increasing temperature. Water molecules can replace adsorbed oxygen on the ZnO surface. At high relative humidity, more oxygen was replaced by water. In this way, the density of the ZnO film increased and less oxygen was left on the surface to be desorbed by UV, both of which contributed to a lower UV response. Reducing gases, such as acetone, can react with the surface adsorbed oxygen and reduce the density of the ZnO film, resulting in UV response degradation.     

导电聚合物薄膜声表面波传感器敏感特性研究

利用旋涂方法在声表面波(SAW)器件的延迟通道上制备了酞菁铜(CuPC)掺杂的聚乙烯吡咯烷酮(PVP)敏感薄膜,并对制备的薄膜用四探针法和扫描电子显微镜(SEM)进行了测试和表征。结果表明:薄膜中的CuPC颗粒均匀分散在聚合物薄膜中,其粒径尺寸约为20 nm,薄膜的电导率在10-6Ω-1.cm-1量级。根据提出的理论模型,计算出由于敏感膜的质量变化与电导率的变化导致了中心频率的漂移,该漂移值的理论计算结果与实验验证结果相符。     

ZnO压电薄膜声传感器的有限元分析

阐述了ZnO压电薄膜声传感器的结构和工作原理,并用ANSYS 9.0对压电薄膜声传感器进行了静态分析、模态分析和谐响应分析。通过静态分析,得到压电薄膜声传感器的灵敏度为16.4 mV/Pa;模态分析得出了传感器的第一阶固有频率为12.379 kHz;谐响应分析则获得感应电压与动态外力频率之间的关系。这些分析为此类声传感器的设计提供了理论依据。     

基于声表面波技术探测微量气体的理论分析

声表面波延迟线振荡器的频率对沉积在延迟线表面上的薄膜很敏感,在延迟线路径上覆盖一层具有选择性的吸附薄膜,这层薄膜吸附对其敏感的气体物质后,其质量密度、弹性参数、介电常数、电导率都将发生变化。给出了传感器的理论分析,根据检测需要,设计最优化的气体传感器。     

基于超支化聚合物的声表面波化学毒剂传感器

基于声表面波（SAW）技术的化学毒剂传感器在检测下限、响应速度以及减小温度、湿度交叉敏感等方面还需进一步提高。提出了在SAW双端口谐振器上涂敷超支化聚合物的方法提高传感器的检测下限和灵敏度。通过建立Van Dyke模型,分析了敏感膜对SAW化学毒剂传感器Q值、插入损耗以及电路阻抗匹配的影响。利用谐振器代替延迟线,确保了器件具有插入损耗、高Q值的特点。实验证实,在谐振器的中心栅结构上涂覆聚合物可以减小粘弹性聚合物对谐振器插损、Q值以及输入输出阻抗的影响。对设计的化学毒剂传感器进行了沙林毒剂检测实验,采用315MHz的SAW谐振器结合超支化聚合物膜,检测沙林气体浓度为5．0mg／m^3。实验表明：这种传感器的灵敏度可达到600Hz／mg／m^3,响应时间为50s,恢复时间约为60s。     

High Q, high frequency, high overtone bulk acoustic resonator with ZnO films

Bulk acoustic wave resonators with piezoelectric films have been widely explored for the small size and high quality factor (Q) at GHz. This paper describes a high overtone bulk acoustic resonator (HBAR) based on Al/ZnO/Al sandwich layers and c-axis sapphire substrate. ZnO film with high quality c-axis orientation has been obtained using DC magnetron sputtering. The fabricated HBAR presents high Q at the multiple resonances from a 0.5–4.0 GHz wide band with a total size (including the contact pads) of 0.6 mm×0.3 mm×0.4 mm. The device exhibits the best acoustic coupling at around 2.4 GHz, which agrees with the simulation results based on the one-dimensional Mason equivalent circuit model. The HBAR also demonstrates Q values of 30 000, 25 000, and 6500 at 1.49, 2.43, and 3.40 GHz, respectively. It is indicated that the HBAR has potential applications for the low phase noise high frequency oscillator or microwave signal source.     

声表面波NO_2传感器敏感膜研究进展

由于工业检测、环境监测、医学监测等领域的需求,高性能NO2传感器得到了广泛的研究。声表面波传感器技术的发展为研发高灵敏度、高稳定性、响应快速、小型化的NO2传感器提供了极大的潜能。总结了近30年来声表面波NO2传感器敏感膜的研究现状,并根据现有的研究和传感器的应用需求,深入探讨了声表面波NO2传感器敏感膜面临的挑战和发展趋势。     

覆盖聚合物敏感膜的水平剪切型声表面波气体传感器机理分析

采用微扰理论分析了覆盖聚合物敏感膜的水平剪切型声表面波气体传感器(SH-SAW)的响应机理。以针对有机磷毒剂具有良好选择性的含氟多羟基聚硅氧烷(FPOL)膜材料为例,分析了聚合物膜厚以及传感器工作频率在敏感膜吸附气体时对传感器响应的影响。计算结果表明,SH-SAW气体传感器对于不同浓度的甲基磷酸二甲酯(DMMP)气体响应随FPOL膜厚和传感器工作频率的改变呈现非线性变化。为了获得线性特性的传感器响应及较小的声波衰减,在一定的DMMP气体浓度检测范围内,通过理论计算提取出了优化的FPOL敏感膜膜厚和传感器工作频率等参数。     

Hydrogen sensor based on antimonium pentoxide-phosphoric acid solid electrolyte

A solid composite electrolyte with high proton conductivity based on antimonium pentoxide with additives of phosphoric acid has been obtained. A potentiometric solid-state gas sensor using this electrolyte has been developed for detecting small amounts of hydrogen (10–2000 ppm) in gas mixtures at ambient temperature. The sensor consists of the reference electrode: Ag or Ag/(Ag + Ag₂SO₄), the solid composite electrolyte and H₂-sensitive electrode: Pt or Pd. The electromotive force (e.m.f.) of the sensor varies logarithmically with H₂ concentration for hydrogen partial pressures in the range 100–2000 ppm and depends on the oxygen partial pressure. The slope of e.m.f.-log(pH₂) dependence is 170 and 200 mV for Pt and Pd, respectively, which exceeds the Nernst value, presumably due to the formation of a mixed potential. The sensor can operate at a wide range (20–95%) of a relative humidity.     

A nitric oxide gas sensor based on Rayleigh surface acoustic wave resonator for room temperature operation

A Rayleigh surface acoustic wave (RSAW) resonator with polyaniline/tungsten oxide nanocomposite thin film is investigated as a gas sensor for detecting the presence of nitric oxide (NO) in air. The sensor developed in this work was sensitive to NO gas at room temperature. It is shown that the sensor had a frequency shift of 1.2 ppm when it was exposed to 138 ppb NO. The negative frequency response increased with NO concentration increasing. The response and recovery times of the NO sensor in this work were about 20-80 s. In addition, this RSAW sensor also exhibited reversibility and repeatability to the presence of NO gas. Especially, the presented sensor showed high selectivity with NO gas to separate from NO₂ and CO₂ gases.     

A microfluidic based differential plasmon resonance sensor

A new type of differential surface plasmon (SPR) sensor integrated with a microfluidic system is presented. The working principle of the microfluidic device is based on hydrodynamic modulation of two laminar streams inside a microchannel to provide periodic changes of the environment on the SPR sensor. The modulated reflectance is then demodulated using a lock-in amplifier. The presented sensor provides sensitivities of index of refraction about 4 × 10⁻⁸ RIU together with a 4 orders of magnitude dynamic range. This method demonstrates a sensitive detection scheme which could be used for label-free detection.     

Pd/PVDF thin film hydrogen sensor system based on photopyroelectric purely-thermal-wave interference

A novel sensitive solid-state sensor system for trace hydrogen gas detection has been developed as a next generation device to earlier photopyroelectric (PPE) hydrogen sensors. The basic principle of the sensor is based on the technique of PPE purely-thermal-wave interferometry recently developed in this Laboratory. The active element of the sensor is a thin polyvinylidene fluoride (PVDF) pyroelectric film, sputter-coated with Pd on one surface and with a Ni–Al alloy electrode on the other surface. Unlike the conventional PPE hydrogen sensors, this new sensor produces a coherent differential PPE signal in a single detector, rather than using two detectors (one active, the other reference) and complicated electronics. The measurement results show that the signal noise level, the detectivity and the signal dynamic range are improved by more than one order of magnitude compared with the conventional single-beam method. The operating characteristics have been examined for three different thicknesses of Pd coating on the same thickness PVDF-film detector. The signal generating mechanism, attributed to the change of the optical absorptance of the Pd coating when exposed to hydrogen, and/or the shift in the Pd work function, is also discussed.     

基于单声学矢量传感器的最大能量动态声源波达方向跟踪算法

针对在空域非均匀噪声环境下目标定位跟踪问题,提出一种基于单声学矢量传感器的最大能量动态声源波达方向(DOA)跟踪算法.首先结合噪声协方差矩阵估计结果实现对传感器接收信号的预白化处理,进而确定加权参数值,提出一种加权参数固化的最大能量算法,从而在声压与振速域噪声功率比未知的条件下提高了DOA估计精度.在此基础上,利用最大能量定向估计子输出信息来构建运动目标的量测方程,并在容积Kalman滤波框架下实现对于动态声源的状态跟踪.理论分析与仿真结果验证了算法的可行性和有效性.     

基于FPGA的双声传感器定位系统的设计

针对小体积声探测系统对阵元数量的要求,设计了基于FPGA的双声传感器定位系统。该定位系统利用两个声传感器接收的回波的声压和时延值进行联合定位,可以达到减小阵元数量的目的。同时,利用硬件描述语言和DSP Builder完成了整个系统的构建。仿真和实验结果表明,所设计的定位系统工作频率可以达到94.4 MHz,完成一次定位只需要52μs,定位误差在1%之内。     

基于薄膜工艺的乙醇气体气敏膜的研究

ZnO2,SnO2,Fe2O3等基底材料可以用来制作半导体型乙醇气体传感器中的气敏膜。在基底中掺杂Pt,TiO2等物质可以获得很高的气体检测灵敏度和很好的选择性。利用电子枪蒸发薄膜工艺来制作乙醇气体敏感膜,可以取得很好的效果。与通常使用的厚膜工艺相比,薄膜工艺与MEMS工艺兼容,更适合制作微小器件。