FBAR传感器信号处理电路的设计

介绍了AIN薄膜体声波(FBAR)传感器以及信号处理电路的原理,着重设计了传感器的频率检测电路.频率检测电路采用VHDL语言对各个电路子模块编写相应的代码,并利用Quartus9.0完成了仿真.仿真结果表明,相对精度为10-6,达到了预期的设想,满足了FBAR传感器的要求.     

基于电容-电阻转换原理的柔性压力传感器

目前,基于碳基纳米材料的柔性压力传感器凭借着其便携性、柔韧性、生物相容性和低成本等特点,在智能医疗、人机交互和智能机器人等领域有着广泛的应用前景,但如何使其在具有较大量程范围的同时保持较高灵敏度,仍是一个严峻的挑战。提出一种基于氧化石墨烯/碳纳米管（Graphene Oxide/Carbon Nanotube, GO/CNT）复合敏感层的柔性压力传感器,同时以热塑性聚氨酯弹性体（Thermoplastic Polyurethanes, TPU）多孔海绵作为传感器骨架。该GO/CNT@TPU柔性压力传感器的量程范围为0～60 kPa,基于电容-电阻转换原理,当受到较小压力（0～5 kPa）时,传感器以电阻感知为主,灵敏度为0.05777 kPa^-1;当受到较大压力（5～60 kPa）时,传感器以电容感知为主,灵敏度为0.33213 kPa^-1。从而有效地实现了传感器的在宽量程内的高灵敏度检测。     

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.     

基于壳聚糖/碳纳米管/石墨烯/铁氰化镍纳米复合材料构建的电化学适体传感器用于凝血酶的检测

该文利用壳聚糖/碳纳米管/石墨烯/铁氰化镍（CS-CNTs-Gra-FP）纳米复合材料作为电化学探针FP的固载基质,并采用纳米金（nano-Au）吸附凝血酶适体（TBA）,构建了一个高灵敏、无标记的电化学适体传感器。其中CS-CNTs-Gra-FP纳米复合材料和nano-Au的引入不仅增大了电极的比表面积、增强了电子的传输速率,也增加了电活性物质铁氰化镍（FP）的固载量,从而极大地提高了该传感器的灵敏度。实验结果表明,该传感器对凝血酶测定具有良好的线性关系,其线性范围是为0.01 nmol/L-30 nmol/L,检测下限为0.003nmol/L。此外,该传感器制备简单,操作简便,稳定性好,特异性强。     

薄膜体声波谐振器的有限元仿真

随着5G通信技术的日益发展,对通信频段的要求越来越高。传统的射频滤波器受结构和性能的限制,不能满足高频通信的要求。薄膜体声波谐振器(FBAR)作为一种新型的MEMS器件,很好地适应了无线通信系统的更新换代,使FBAR技术成为通信领域的研究热点之一。本文以COMSOLMultiphysics软件为基础,对FBAR谐振元件进行有限元仿真,分析其压电耦合特性、模态特性、谐振特性等。设计的谐振单元,谐振频率在工信部规划的5G通信频段标准(3.4 GHz-3.6 GHz)以内。同时引入完美匹配层(PML)减少寄生共振,更符合实际工艺制备的FBAR的共振特性。实验仿真结果表明,谐振频段在3.510 GHz-3.564 GHz,满足5G通信系统对频段的要求。当谐振位移形式变量满足AlN压电材料的变形范围,计算FBAR的主要性能指标,建立了一种基于COMSOL Multiphysics软件对FBAR的物理结构建模及相关特性研究的实验方法。     

基于微纳泡沫金属材料的D-半乳糖传感器研究

研究了一种基于微纳泡沫镍材料的D-半乳糖定量传感器,采用泡沫镍材料作为工作电极,Pt作对电极,Ag/AgCl（饱和KCl溶液）电极作为参比电极构建三电极检测体系,采用循环伏安法（CV）和电流-时间曲线法（i-t）检测具有浓度梯度的D-半乳糖溶液。CV扫描结果表明了D-半乳糖在泡沫镍材料上发生氧化-还原反应,i-t检测结果表明在线性范围0.25 mmol/L~5.00 mmol/L内该传感器检测D-半乳糖的灵敏度为6.73×10-2 mA/（cm2·（mmol/L））,检测限为17.7μmol/L（S/N=3）。结果证明所构建的检测方法不但可以实现D-半乳糖的定量分析,并且具有较好的灵敏度和较低的检测限。对比实验结果表明该传感器具有响应速度快、成本低廉等优势,有望在糖类物质快速定量检测领域得到应用。     

传感网环境下视频传感器在线规划

针对视频传感器观测被动的问题,结合视频传感器和传感网的特点,设计了传感网环境下视频传感器在线规划框架。该框架采用面向服务的体系架构（ SOA）,包含资源层、资源服务层、规划服务层和应用层四个层,各层之间采用标准的网络通信协议进行通信。实现了视频传感器在线规划原型系统,并以视频监控签到为应用场景进行了在线规划实验。实验结果表明：该框架对于实现视频传感器主动和按需观测是可行且有效的。     

MWNTs与GNPs—CHIT修饰的过氧化氢生物传感器

在玻碳电极（GCE）上自组装一层多壁碳纳米管（MWNTs）,构建负电荷的界面,然后,静电吸附一层阳离子电子媒介体硫堇（Thi）,再由共价键作用自组装一层纳米金（GNPs）,壳聚糖（CHIT）混合溶液的复合薄膜,通过静电吸附辣根过氧化物酶（HRP）制得过氧化氢（H2O2）生物传感器。采用循环伏安法和计时电流法考察了该生物传感器的电化学性质,并研究了该修饰电极对H2O2的催化还原作用。生物传感器的响应电流与H2O2浓度在8．2×10^-6～1．1×10^-3mol／L范围内呈现线性关系,检出限为5．8×10^-7mol／L,达到95％稳态响应时间约为15s。将此生物传感器用于H2O2的检测,结果令人满意。     

基于滑模变结构的WSNs跨层拥塞控制算法

针对具有传输控制协议（TCP）传输机制的无线传感器网络（WSNs）节点拥塞问题,在传输层的基础上结合物理层的信噪比（SNR）参数来估计信道状况,不断调整传输模型,实现跨层控制。此跨层方法改变了以往的单层拥塞控制方法,充分利用了WSNs层与层的协作关系,并用基于自适应趋近律的离散滑模控制结构模型作为控制器,过程简单且易于实现。仿真结果表明：该跨层拥塞控制方法具有响应速度快、延迟小、鲁棒性好等特点。     

一种适用无源RFID的集成加速度传感器设计

针对射频识别（ RFID）与无线传感器网络（ WSNs）融合研究的需要,基于0.35μm CMOS工艺设计了一种集成加速度传感器。传感器单元采用从单晶硅衬底的背面进行深反应离子刻蚀工艺,背面刻蚀完成后再正面对金属和介质复合层进行各向异性刻蚀。集成电容式传感器接口电路基于锁相环原理,将传感器信号转移到频率域处理,避免了高功耗的A/D转换器的使用,直接完成电容/数字转换。后期测试结果显示：所设计的集成加速度传感器线性度好,稳定性高,功耗低,适合无源RFID及其它超低功耗应用设计。     

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.     

Characteristics of a label-free piezoelectric immunosensor detecting Pseudomonas aeruginosa

A label-free immunosensor system detecting a psychrophylic bacterium, Pseudomonas aeruginosa was developed as follows. Four types of anti-P. aeruginosa antibody were individually chemisorbed onto one-side gold electrodes of piezoelectric quartz crystals according to a thiolated antibody coupling procedure initiated with a thiol-cleavable heterobifunctional cross-linker, sulfosuccinimidyl-6-[3-(2-pyridyldithio)propionamido]hexanoate. A flow-type biosensor system was operated optimally at 0.2 M sodium potassium phosphate, pH 7.2 with a minimal matrix effect and the selected flow rate for it was 0.155 ml/min. A biosensor response was detected by measuring a steady-state resonant frequency shift after the response time around 8 min. The frequency shifts obtained were quite specific according to the antibody types and P. aeruginosa strains. The biosensor responses to varying concentrations of the P. aeruginosa cells ranging from 1.3×10⁷ to 1.3×10⁸ CFU/ml were determined as 17–176 Hz and a linear calibration curve (r=0.942) was obtained by plotting the responses in a double-logarithmic scale. The selectivity of the biosensor between P. aeruginosa and Xanthomonas spp. which both belong to the aerobic pseudomonads was, however, not so good owing to the property of the antibody used. The sensor chip could be reused at least seven times without an appreciable decrease in sensitivity.     

Signal enhancement of surface plasmon resonance-based immunoassays for the allergen detection

A surface plasmon resonance (SPR) biosensor was used to determine the recombinant group 1 house dust mite allergen (rDer f1) in both HBS-EP buffer and fetal bovine serum (FBS). The monoclonal antibody was immobilized onto the CM5 sensor chip surface using an amine coupling method. The procedures of antibody immobilization and the subsequent primary and enhanced immunoassay were monitored in real time. The sensitivity for rDer f1 detection was remarkably improved by using intact polyclonal antibody as signal amplifying agent. Using this signal enhanced SPR immunosensor, rDer f1 in HBS-EP buffer and FBS was detected at a concentration of 15.4 and 32.1 ng/ml, respectively. The result demonstrates that SPR biosensor is a simple and reliable method for allergen detection.     

Detection of sulphamethazine with an optical biosensor and anti-idiotypic antibodies

We describe the development of an assay for the detection of sulphamethazine in animal urine with a surface plasmon resonance (SPR) biosensor. In order to obtain a general assay that can easily be transferred to other veterinary drug residues, a monoclonal antibody against sulphamethazine and a corresponding anti-idiotypic antibody were used. The assay had a lower detection limit of 5 μg/l which is well below the maximum residue limits (MRL) of 100 μg/l and can be used for screening purposes in animal urine. The binding reaction between the antibodies as occurring during sensor application was characterized with respect to avidity and kinetic properties.     

Micromachined Acoustic Resonant Mass Sensor

This paper describes a highly sensitive, film bulk acoustic resonator (FBAR) mass sensor (built on a micromachined silicon-nitride diaphragm with a piezoelectric thin film and Al electrodes) that can operate in vapor and liquid. The sensitivity of the device to mass change on its surface has been investigated by having various thicknesses of silicon-nitride support layer and also of Al layer. The sensor is measured to have a mass sensitivity of 726 cm$^2$/g, which is about 50 times that of a typical quartz crystal microbalance (QCM). In vapor, the sensor (operating at around 1 GHz and having a relatively high quality (Q) factor of 200–300) shows a minimum detectable frequency shift of about 400 Hz, which corresponds to a mass change of$10^-9$g/cm$^2$on the sensor surface, comparable with that detectable by a QCM. In liquid, though the Q usually drops more than an order of magnitude, we obtain a Q of 40 at 2 GHz by using a second harmonic resonance of the resonator. And with the Q, a minimum 5 ppm resonant frequency shift can be detected, which corresponds to$10^- 8$g/cm$^2$change on the sensor surface.hfillhbox[1374]     

薄膜体声波谐振器的结构参数优化分析

建立了微型薄膜体声波谐振器的等效电路模型,研究其整体频率响应特性.提出的等效电路模型考虑了氧化锌压电薄膜两端电极和作为支撑层的氮化硅薄膜对谐振器整体性能的影响,将它们作为传输线引入到等效电路当中.运用PSPICE软件研究了谐振器各结构层的尺寸参数对谐振器谐振频率、品质因数和有效机电耦合系数的影响,并讨论了使用不同材料的电极,谐振器品质因数的变化情况.基于以上分析,对谐振器的结构参数进行优化,获得薄膜体声波谐振器性能的提高.     

Orientation and capturing of antibody affinity ligands: Applications to surface plasmon resonance biochips

A surface plasmon resonance (SPR) sensor chip with immobilized protein G was used for simultaneously capturing, purifying and orienting antibody ligands. The ligands were further stabilized by chemical cross-linking. This procedure of designing the sensor chip improved efficient use of the ligands and could prolong the analytical use.The procedure was evaluated on standard dextran-coated sensor chips onto which commercial semi-purified antibodies towards human serum albumin and human troponin where captured and used for analysing their antigens.The procedure demonstrates a general design approach for presenting the biorecognition element on a biosensor surface which enhances sensitivity, stability and selectivity at the same time as an impure ligand is purified.     

Electrochemical performance of a DNA-based sensor device for detecting toxic algae

This work illustrates the electrochemical performance of a DNA-based sensor device for detecting toxic algae. This biosensor uses an electrochemical detection of the species in a sandwich hybridisation. A thiol (biotin) labelled capture probe was immobilized onto gold (carbon) electrodes. Synthetic positive control DNA was applied to the sensor and allowed to hybridize to the capture probe. A signal probe with a horseradish peroxidase (HRP) label was then applied, followed by an antibody to the HRP and a substrate. The electrical signal obtained from the redox reaction was proportional to the amount of DNA applied to the biosensor, which in turn would be proportional to the number of cells harvested when applied to real samples. Optimization of the hybridization process was already achieved in a previous work. Elucidation of the different steps of the fabrication process from the electrochemical point of view, proof of concept with different algal species and evaluation of the influence of the transducer platform geometry and material in the biosensor analytical performance are the main achievements reported here.     

Determination of 3-nitrotyrosine in human urine samples by surface plasmon resonance immunoassay

This paper describes the detection of a low-molecular weight molecule, 3-nitrotyrosine (3-NT) (∼226 Da), in human urine by coupling indirect inhibition assay with a surface plasmon resonance (SPR) sensor. 3-NT antibody (anti-3-NT Ab, mouse IgG) was used in this assay. An optimal antibody concentration has been measured at 27.9 μg/mL in order to obtain the best performance of the sensor surface. The lowest detection limit for 3-NT with this method is 4.7 ng/mL (S/N = 3). Sensor reliability was demonstrated by good specificity, intra-assay and inter-assay relative standard deviations <8%, average recovery of 107.68 ± 19.4% and sensor surface (self-assembled monolayer) stability through more than 200 regeneration cycles and 15 days of repeated measurement. This is the first SPR biosensor assay of 3-NT in human urine. The high stability of the SPR sensor surface underlies the potential of the SPR method as a low cost diagnostic tool for clinical detection of 3-NT.