基于带通滤波器的幅频特性调节光电开关灵敏度

研究探讨了调制光频率与检测距离的相关性,旨在通过软件改变红外调制光频率,实现"一键式"智能调节检测距离.以连续周期矩形脉冲信号为例,选用二阶窄带带通放大电路对输入信号进行放大和滤波处理,使不同频率的脉冲信号经过窄带带通放大器自动调节其输出信号幅度,进而影响传感器的灵敏度.经理论推导、仿真设计、实验分析,结果表明:当设定脉冲幅值和占空比为常数时,改变脉冲信号频率可实现传感器灵敏度的调节,从而实现对检测距离的调节.即当ff0时,灵敏度随着f增大而减小.在红外光电开关传感器上应用该方法实现了利用软件调节频率来调节传感器的测量距离.     

基于光电复合传感器的重金属检测算法的研究

基于光寻址电位传感器(Light Addressable Potentiometric Sensor,LAPS)和微电极阵列传感器(Microelectrode Array Sensor,MEA)的复合传感器件,作为无线传感器网络的敏感元件,已应用于水环境痕量重金属的检测中.本文基于该光电复合传感器,分别对LAPS及M...     

光纤传输LD推动系统的研究

本文介绍一种用光纤做光通道、激光二极管(LD)做激光源的光功率推动传感器的工作原理,微功耗测量探头的设计方法,脉冲位置调制中应用单根光纤分时双通道解决参考信号的设置,以及光反馈稳定光源等技术.上述措施使传光型光纤传感器的系统稳定性和精度等性能指标得到很大改善.由于被测信号也采用了光纤传输,使探头与仪表端只有光联接,所以本文介绍的光推动传感器可视为“准”全光学式的.     

光寻址电位传感器信号的实时采集与数据管理——基于数据库和TeeChart的实时动态采集、显示和管理

光寻址电位传感器(LAPS)是一种基于集成电路制造技术的传感器,在生物化学领域有着广泛的应用前景。使用专用图表控件和数据库技术为LAPS测控系统建立了数据采集与管理系统,实现了LAPS输出信号的实时采集与动态显示,并采用数据库的形式对检测结果进行实时存储和历史查询,有助于进一步推进LAPS系统在应用领域的发展。     

光寻址电位传感器的自相关检测方法

针对基于光寻址电位传感器的微流控芯片信噪比低的问题,提出了一种基于自相关检测的光寻址电位传感器信号提取方法。采用气液分离的方法在微流路内产生了体积约1μL的样品微滴,对比了光寻址电位传感器在方波激励与正弦波激励下检测微滴的I/V特性曲线,以及在相同条件下的I-f特性曲线。结果表明：采用自相关检测法,光寻址电位传感器具有53.8 mV/pH的灵敏度,其信噪比提高了7.020 6 dB。研究结果对于微型LAPS光电流信号高精度检测做出了有益探索,具有良好的应用前景。     

小波变换在神经细胞传感器信号去噪中的应用

将神经元培养在半导体传感器芯片表面,构建出能够对细胞电生理特性进行长时程无损测量的神经细胞传感器,具有广阔的生物医学应用前景.由于生物信号非常微弱,采集到的信号往往难以满足实际检测的需要.本研究针对培养在光寻址电位传感器(LAPS)芯片表面的PC12细胞的胞外电生理信号,采用小波变换方法对其进行去噪处理.通过小波变换将信号分解为不同层次的小波系数,得到每一层的阈值.并根据每一层系数特点,按阈值进行分别处理,得到新的小波系数,最后根据该系数,重构了信号.对去噪后的信号进行频谱分析,发现有效信号频率集中在小于2 kHz的范围内,信噪比得到提高,表明小波变换是神经细胞传感器信号去噪的有效方法.     

阵列调制随机共振在微弱信号特征提取方面的应用

论述了阵列调制随机共振方法在强噪声背景下多频微弱信号特征提取中的工作原理和实现步骤;采用预先设定系统参数的多个并联非耦合随机共振单元形成阵列,将被测强噪声背景下的多频微弱信号分别与不同频率的载波进行调制,生成多个差频均为0.01Hz的信号作为各对应随机共振单元的激励信号,采用龙格-库塔算法求取各单元输出并进行频谱分析,根据0.01Hz处的信噪比判断在微弱信号中是否存在载波频率与差频值之和大小的频率分量,最后综合各个随机共振单元的检测结果生成微弱信号的频率特征向量;仿真结果表明,阵列调制随机共振在微弱信号特征提取方面效果明显,具有很好的应用前景。     

干涉型光纤传感器解调方法改进与研究

通过分析光纤干涉仪输出信号成分和理论推导,提出了干涉型光纤传感器相位生成载波(PGC)调制解调技术的改进方案,通过实验仿真得出,新方案不需要AGC模块就可以消除干涉仪输出光功率漂移对解调结果的影响,而且系统的最低采样频率减低了约1/3.     

基于SOA脉冲调制的BOTDR应变检测系统

电光调制器调制光脉冲时易受偏振态与偏压影响,造成调制脉冲平均功率与消光比不稳定,影响检测系统稳定性,实际中需通过复杂算法校正。本文提出半导体光放大器调制光脉冲的方法,通过改变注入泵浦电流调制光脉冲,采用相干探测结合微波频率扫描方法,获取不同频率点下自发布里渊散射信号,经洛伦兹拟合得到布里渊散射谱,实现光纤沿线布里渊频移解调,并搭建了基于半导体光放大器的BOTDR分布式应变检测系统。实验中选取2.943km光纤末端施加500με,频移测量误差在±0.5MHz范围内。研究表明可实现稳定应变检测。     

基于单传感器动态检测和神经网络的气体监测

研究了气体传感器动态检测结合神经网络识别空气中有机气体的新方法.这种方法利用单个SnO2气体传感器而非阵列在方波温度调制的状态下,可实现多种有机气体的定性分析.在0.02Hz的调制频率、250～300℃的温度调制范围,测得传感器对不同体积分数异丙醇、乙酰丙酮和乙醇气体的动态响应.通过小波变换对单个周期测试信号进行特征提取,并将提取的特征值输入神经网络进行定性识别和体积分数估计,仿真识别的成功率高达100%,同时,较准确地实现待测有机气体的体积分数估计.     

A high-density multi-point LAPS set-up using a VCSEL array and FPGA control

A new LAPS (light-addressable potentiometric sensor) set-up will be introduced, in which the light sources are miniaturised by the utilisation of a VCSEL (vertical-cavity surface-emitting laser) array to increase the measurement spot density. An FPGA (field-programmable gate array) is used to generate modulation signals for individual illumination of each measurement spot of the LAPS. The new set-up can operate a large number of measurement spots simultaneously by reading out the sum photocurrent and separate the signals of the individual measurement spots by an FFT analysis. The frequency, amplitude and offset of the modulation signal can be configured for each measurement spot by software. The new system can be combined with a positioning stage allowing the parallel read out of a single line of measurement spots and a scan perpendicular to that line in a similar manner, like for an optical scanner set-up. First measurements demonstrate the functionality of the new LAPS set-up as a chemical imaging system.     

Phase-mode LAPS and its application to chemical imaging

The light-addressable potentiometric sensor (LAPS) is a chemical sensor based on the field effect in the electrolyte-insulator-semiconductor (EIS) structure. In the conventional LAPS, the ion concentration in the analyte solution in contact with the sensing surface is determined by measuring the amplitude of the photocurrent induced by illumination. In this study, we developed the phase-mode LAPS, in which the phase of the alternating photocurrent is measured instead of its amplitude. The phase-voltage curve shifted along the voltage axis in response to the variation of the ion concentration in analogy to the shift of the amplitude-voltage curve in the conventional LAPS. The primary advantage of the phase-mode LAPS is that it is much less sensitive to the variation of the light intensity. It is also demonstrated that chemical imaging based on the phase-mode LAPS is free from artifacts related to defects in the semiconductor substrate.     

Constant-phase-mode operation of the light-addressable potentiometric sensor

The constant-phase-mode operation of the light-addressable potentiometric sensor (LAPS) is proposed and demonstrated. In this new operation mode, the temporal change and the spatial distribution of the analyte concentration are recorded in the form of the bias voltage applied to the LAPS sensor plate, which is servo-controlled to maintain the phase of the photocurrent at a constant value with respect to the light modulation. The constant-phase-mode LAPS is advantageous for its wider measurement range and reduction of artifacts.     

基于微透镜阵列的多通道光寻址电位传感器研

为了提高化学和生物图像传感器的成像速度和简化成像系统,提出了一种基于微透镜阵列的多通道光寻址电位传感器.利用微透镜阵列把单束激光转化成点阵,通过多频率斩波器,得到不同频率的光点阵列用作光寻址电位传感器的光源,从而实现多点同时检测.实验结果表明该系统具有良好的频域分辨率,通过数字补偿技术可获得各个检测点的电流电压特性曲线,证明可实现多点同时检测.该系统可以用于光寻址电位传感器和扫描光感阻抗传感器的快速成像,以及多通道化学生物图像检测.     

基于光电复合传感器的重金属原位监测系统嵌入式软件设计

针对水环境重金属监测仪器,设计了一种智能化嵌入式软件。该仪器采用光电复合传感器芯片,包括微阵列电化学传感器和光电位寻址传感器。仪器设计了可靠稳定的通信机制与上位机进行人机交互,仪器具有智能化自检功能,能够及时反馈传感器的故障信息。在检测过程中具有自动量程功能,能够最大发挥硬件优势,同时具有误差补偿和电路异常的检测机制。仪器具有高稳定性、自动化检测的特点,并完成了在野外无人值守的条件下的检测任务。     

Optoelectronic implementation of pulsed neurons and neural networks using bispin-devices

Optoelectronic spiking neuron that is based on bispin-device is described. The neuron has separate optical inputs for excitatory and inhibitory signals, which are represented with pulses of single polarity. Experimental data, which demonstrates similarity in form of output pulses and set of functions of the suggested neuron and a biological one is given. An example of hardware implementation of optoelectronic pulsed neural network (PNN) that is based on proposed neurons is described. Main elements of the neural network are a line of pulsed neurons and a connection array, part of which is made as a spatial light modulator (SLM) with memory. Usage of SLM allows modification of weights of connections in the learning process of the network. It is possible to create adaptive (capable of additional learning and relearning) optoelectronic PNNs with about 2000 neurons.     

In vitro assessing the risk of drug-induced cardiotoxicity by embryonic stem cell-based biosensor

Drug-induced prolongation of ventricular repolarization with arrhythmia is a major concern in clinic safety pharmacology, and has been a common reason for the withdrawal of several promising drugs from the market. Therefore, novel techniques should be developed to evaluate cardiotoxicity of new drugs in preclinical research. A cardiomyocyte based biosensor was developed using the light addressable potentiometric sensor (LAPS). Mouse embryonic stem cells cultured on the surface of LAPS were induced to differentiate into synchronized spontaneity beating cardiomyocytes. Changes of extracellular potentials and cell shapes with their mechanical beatings could induce modulation of photocurrents in the LAPS system, and finally change the output of the sensor. With the characteristics of light addressability, LAPS can record cell clusters at any desired position. The sensor can be used to record the prolongation of ventricular action potentials with the cardiotoxicity induced by drugs such as amiodarone, levofloxacin, sparfloxacin, and noradrenaline. The quick and on time characteristics of the sensor were promising to establish a high-throughput platform for pharmacological toxicity investigation.     

基于光电复合传感器的重金属监测系统嵌入式软件设计?

针对水环境重金属监测仪器,设计了一种智能化嵌入式软件。该仪器采用光电复合传感器芯片,包括微阵列电化学传感器和光电位寻址传感器。仪器设计了可靠稳定的通信机制与上位机进行人机交互,仪器具有智能化自检功能,能够及时反馈传感器的故障信息。在检测过程中具有自动量程功能,能够最大发挥硬件优势,同时具有误差补偿和电路异常的检测机制。仪器具有高稳定性、自动化检测的特点,并完成了在野外无人值守条件下的检测任务。     

Elimination of noise on transcranial Doppler signal using IIR filters designed with artificial bee colony – ABC-algorithm

Biomedical signals are usually contaminated by noise generated from sources such as power line interference and disturbances produced by the movement of the recording electrodes. Also the signal-to-noise ratio of biomedical signals is usually quite low. In addition, biomedical signals often interfere with each other. Therefore, the filters employed for eliminating noise and interference are significant in the medical practice. Digital infinite impulse response (IIR) filters have shorter filter length than the finite impulse response (FIR) filters with the same frequency characteristic. Therefore, in this work, an approach based on digital IIR filters are described for the elimination of noise on transcranial Doppler by using artificial bee colony (ABC) which is a popular swarm based optimization algorithm introduced recently. Moreover, the performance of the proposed approach is compared to particle swarm optimization algorithm.