Development of tactile sensor for measuring hair touch feeling

In this paper, a tactile sensor system for evaluation of human hair under dry and wet conditions is developed. The polyvinylidene fluoride (PVDF) film is used as the sensory material. The sensor consists of an acrylic base, a silicone rubber, a PVDF film. A surface projection is put on the PVDF film as the contacting part. The sensor output is obtained by contacting and scanning objects. Panels imitating the physical and chemical properties of human hair surface are fabricated and used as measuring objects for stable measurement. Panels cleaned down with several kinds of hair-care products are measured by the sensor. By comparison between the sensor output and human sensory evaluation, it was confirmed that the sensor outputs have a good correlation with human sensory evaluation. It was found that the sensor system is available for monitoring hair conditions in both dry and wet conditions.     

阵列式压电模态传感器的实验研究

通过一组阵列式压电薄膜,设计未知边界条件下振动梁的模态传感器。在梁表面均匀布置一组具有相同形状的矩形聚偏氟乙烯(PVDF)薄膜,通过测量PVDF输出与激励力之间的频率响应函数,利用伪逆方法设计这组PVDF的加权系数,从而实现对结构模态坐标的测量。实验研究表明:该方法设计的模态传感器具有良好的滤波效果,非目标阶模态坐标峰值与目标阶相比,下降了12 dB以上,并且不需要预先知道结构的边界条件或者模态信息。进一步讨论了当振动梁的边界条件发生微小扰动时所设计模态传感器的鲁棒性。     

通过PVDF阵列测量体积位移的实验研究

针对目前PVDF体积位移传感器的研究主要集中在经典边界条件(如简支、固定、自由等)、需要预知精确的边界条件等不足,提出通过伪逆方法结合Tikhonov正则化方法设计振动梁在任意未知边界条件下的压电式体积位移传感器的通用设计模型。以一未知边界条件的振动梁为例,用一组PVDF阵列测量其体积位移。在该梁表面均匀粘贴一组相同形状的矩形PVDF薄膜,然后通过所提出的新方法设计这组PVDF输出信号的加权系数,从而得到体积位移。实验结果表明这种传感器设计方法是可行的,并且不需要预知振动梁的边界条件或模态信息。     

An evaluation of an olfactory sensor and recognition system using metal-oxide semiconductor gas sensor with variable heater controller

An artificial olfactory, which is called an electronic nose system (e-nose), is studied for realizing new human–machine interface. The system consists of sensor unit and a signal processing unit. There are some types of sensors for the sensor unit, metal oxide semiconductor gas sensors (MOGS) and quartz crystal microbalance gas sensors are useful in our study. Our system in this paper has MOGS. Many of MOGS utilize an effect of an oxidation–reduction reaction on the surface of the sensors. One of the features of the sensor, the character of the sensor is changed by temperature of the sensors. In this paper, we build a extend output sensor unit using this feature, and show experimental result of classification applying multilayer perceptron. In the experiment, we choose soy sauce as classification targets because we are considering applying the system for management of cooked foods.     

热电薄膜型气体流量传感器的热模拟分析

利用有限元分析工具ANSYS/FLOTRAN ,模拟并分析了一个基于薄膜结构的热电型气体流量传感器的温度场。并具体地分析了在气体流量通道入口处气体的流向角度对传感器输出信号以及气体流动状态的影响。将最终的模拟计算结果与实验数据进行比较 ,发现二者基本吻合。利用此热学模型来模拟和分析此类传感器 ,不但可以减少大量的模拟分析过程而且可以降低计算的复杂度 ,另外也为此类传感器的设计和验证提供了一个非常简单而有效的方法和依据。     

Tactile sensors based on conductive polymers

This paper presents results from a selection of tactile sensors that have been designed and fabricated. These sensors are based on a common approach that consists in placing a sheet of piezoresistive material on the top of a set of electrodes. We use a thin film of conductive polymer as the piezoresistive material. Specifically, a conductive water-based ink of this polymer is deposited by spin-coating on a flexible plastic sheet, giving it a smooth, homogeneous and conducting thin film. The main interest in this procedure is that it is cheap and it allows the fabrication of flexible and low cost tactile sensors. In this work, we present results from sensors made using two technologies. Firstly, we have used a flexible printed circuit board (PCB) technology to fabricate the set of electrodes and addressing tracks. The result is a simple, flexible tactile sensor. In addition to these sensors on PCB, we have proposed, designed and fabricated sensors with screen-printing technology. In this case, the set of electrodes and addressing tracks are made by printing an ink based on silver nanoparticles. The exhaustive characterization provides us insights into the design of these tactile sensors.     

Capacitive flexible pressure sensor: microfabrication process and experimental characterization

Kapton-based flexible pressure sensor arrays are fabricated using a new technology of film transfer. The sensors are dedicated to the non-invasive measurement of pressure/force in robotic, sport and medical applications. The sensors are of a capacitive type, and composed of two millimetric copper electrodes, separated by a polydimethylsiloxane (PDMS) deformable dielectric layer. On the flexible arrays, a very small curvature radius is possible without any damage to the sensors. The realized sensors are characterized in terms of fabrication quality. The inhomogeneity of the load free capacitances obtained in the same array is ±7 %. The fabrication process, which requires 14 fabrication steps, is accurate and reproducible: a 100 % transfer yield was obtained for the fabrication of 5 wafers gathering 4 sensor arrays each (215 elementary sensors). In the preliminary electro-mechanical characterization, a sensor (with a PDMS dielectric layer of 660 μm thickness and a free load capacitance of 480 fF) undergoes a capacitance change of 17 % under a 300 kPa normal stress.     

Distributed state estimation for uncertain sensor networks with mixed time delays subject to sensor saturations

In this paper, the distributed state estimation problem is investigated for a class of uncertain sensor networks. The target plant is described by a set of uncertain difference equations with both discrete-time and infinite distributed delays, where two random variables are introduced to account for the randomly occurring nonlinearities. The sensor measurement outputs are subject to randomly occurring sensor saturations due to the physical limitations of the sensors. Through available output measurements from each individual sensor and its neighboring sensors, this paper aims to design distributed state estimators to approximate the states of the target plant in a distributed way. Sufficient conditions are presented which not only guarantee the estimation error systems to be globally asymptotically stable in the mean square sense but also ensure the existence of the desired estimator gains.     

不同长度敏感元件的两种巨磁阻抗传感器传感性能研究

针对采用Co基非晶丝作为敏感元件的传统巨磁阻抗传感器和非对角巨磁阻抗传感器进行比较研究。改变敏感元件的长度,观察两者在直流外磁场作用下输出信号的变化规律,并讨论退磁场等因素对传感器输出信号的影响。结果显示非对角巨磁阻抗传感器具有高灵敏度,无磁滞等优点,且灵敏度随样品长度的减小略有增大,在测量弱磁场方面表现出更大的潜力,为磁敏传感器的小型化提供了一定的参考依据。     

Characterization of layer-by-layer nano self-assembled carbon nanotube/polymer film sensor for ethanol gas sensing properties

This paper reported a multi-wall carbon nanotubes (MWNTs)/polymer film-based sensor for ethanol gas detection. The film sensor was fabricated using layer-by-layer self-assembly method on the substrate with interdigital electrodes structure. The surface morphology of the self-assembled membranes shows a high strength, dense and random network structures, and the electrical properties of MWNTs/polymer film sensor were investigated. Its ethanol gas-sensing properties with varying gas concentration are characterized at room temperature. The experiment results shown that carboxylic groups attached on the MWNTs surface and the expansion of polyelectrolyte interlayer lead to a prompt response and sensitive resistance change when the sensor exposed to ethanol gas, indicating the unique advantages of layer-by-layer self-assembly of MWNTs/polymer film sensors in prospective application.     

Design and optimization of heating plate for metal oxide semiconductor gas sensor

A thin film was coated onto the top of the heating electrodes to reduce the power consumption and improve the uniformity of temperature distribution. Finite element simulation software COMSOL was used to simulate the effect of coating materials and dependence of thicknesses of the coating film on the power consumption of the heating plate. On the basis of simulation, the temperature distribution of different heating plates was measured using infrared thermography. Experiments have showed that the power consumption of the heating plate can be significantly reduced and the temperature uniformity is promoted with adding the coating film on the top of the heating electrodes. The response of the gas sensor based on PdO-WO₃ nanoparticles was characterized with analyte of acetone. It was found that the addition of the coating film could enhance the response to acetone. In addition, the response speed of sensors was investigated with coating films and the results indicated that with the coating film sensor response speed became faster.

     

Fabrication and flow-sensor application of flexible thermal MEMS device based on Cu on polyimide substrate

A Cu on polyimide (COP) substrate was proposed as a MEMS material, and the fabrication process for a flexible thermal MEMS sensor was developed. The COP substrate application to MEMS devices has the advantage that typical MEMS structures fabricated in a SOI wafer in the past—such as a diaphragm, a beam, a heater formed on a diaphragm—can also be easily produced in the COP substrate in the flexible fashion. These structures can be used as the sensing element in various physical sensors, such as flow, acceleration, and shear stress sensors. A flexible thermal MEMS sensor was produced by using a lift-off process and sacrificial etching of a copper layer on the COP substrate. A metal film working as a flow sensing element was formed on a thin polyimide membrane produced by the sacrificial etching. The fabricated flexible thermal MEMS sensor was used as a flow sensor, and its characteristics were evaluated. The obtained sensor output versus the flow rate curve closely matched the approximate curve derived using King’s law. The rising and falling response times obtained were 0.50 and 0.67 s, respectively.

     

多波长边缘电场传感器参数估计算法的研究

多波长边缘电场传感器由于具有单边穿透、多种穿透深度及层析成像等优点,广泛用于工业过程控制中被测多层样本特性的无损测量.如何建立传感器的输出与多层特性之间的关系一直是参数估计算法的研究难点.以三波长交叉指型边缘电场传感器为例,基于三维有限元仿真,建立了多层样本介电特性和互导电容之间的多元非线性回归模型,研究参数估计算法,实验结果表明算法的有效性.     

Sensor placement optimization applied to laminated composite plates under vibration

The location optimization of sensors is a essential problem in structural health monitoring systems. Taking the cost of sensors into account, it is uneconomical to install sensors on every part of a structure and moreover in aeronautical industry, the weight is a crucial factor. In this paper, a optimal placement optimization of sensor locations for structural health monitoring systems is studied. Several techniques of optimization of sensors are approached and applied in a shell structure. The structure, a laminate of carbon fiber, was modeled by the finite element method (FEM) and then subject to free vibration. Genetic algorithms (GAs) are then employed to locate the best sensor distribution to cover a specific number of low frequency modes. Numerical results have demonstrated the overall efficiency of sensor delivery methods. Specific problems occurred, especially regarding the method of effective independence, being less efficient and discrepant in relation to the other methods employed. In summary, the results obtained in this paper provide an optimal position for sensors in real SHM systems and experiments.     

Pd掺杂对SnO_2气敏性能的影响

在气体传感器中金属Pd被广泛用作的催化剂,利用直流溅射和浆料涂覆的方法制备出SnO2气敏元件,在氧气氛中通过直流溅射对SnO2元件进行Pd掺杂,并对用不同制备方法所得元件的电导、灵敏度等进行比较。结果表明:Pd掺杂降低了元件的电导,并使得电导峰出现的位置从460℃转移到260℃和180℃,这和样品的制备方法有关。Pd掺杂有利于提高SnO2元件的灵敏度,特别在低温区(100~250℃)对不同气体的灵敏度有几十倍提高。     

基于方向性SUSAN算子的图像角点特征提取

在不同传感器图像的匹配中角点是重要匹配特征,为满足实际一些具有方向性的成像传感器图像匹配的需要,进行稳定可靠、具有方向性角点特征的检测是必需的.本文采用方向性的SUSAN角点检测算法,将SUSAN算子计算区域限定在具有一定指向的扇区,使之具有方向性检测角点特征.实验证明,该算法简单、实用和有效.     

Design and simulation of a thermo transfer type MEMS based micro flow sensor for arterial blood flow measurement

Thermo transfer type MEMS (Micro Electro Mechanical System) based micro flow sensing device have promising potential to solve the limitation of implantable arterial blood flow rate monitoring. The present paper emphasizes on modeling and simulation of MEMS based micro flow sensing device, which will be capable of implantable arterial blood flow rate measurement. It describes the basic design and model architecture of thermal type micro flow sensor. A pair of thin film micro heaters is designed through MEMS micro machining process and simulated using CoventorWare; a finite element based numerical code. A rectangular cross section micro channel has been modeled where in micro heater and thermal sensors are embedded using the same CoventorWare tools. Some promising and interesting results of thermal dissipation depending upon very small amount of flow rate through the micro channel are investigated. It is observed that measuring the variation of temperature difference between downstream and upstream, the variation of fluid flow rate in the micro channel can be measured. The numerical simulation results also shows that the temperature distribution profile of the heated surface depends upon microfluidic flow rate i.e. convective heat transfer is directly proportional to the microfluidic flow rate on the surface of the insulating membrane. The simplified analytical model of the thermo transfer type flow sensor is presented and verified by simulation results, which are very promising for application in arterial blood flow rate measuring in implantable micro devices for continuous monitoring of cardiac output.     

新型光纤曲率传感器的研究

研制了一种新型的光强调制型光纤曲率传感器,直接以结构的曲率为被测量。通过在传感器的敏感区涂一层石墨来提高传感器的灵敏度,并保护敏感区在安装过程中不被损坏。对该传感器的静态特性进行了实验分析,结果表明：其输出电压与曲率呈较好的线性关系,并具有方向性。基于弯曲光纤端面上各点孔径角的不相同这一理论．提出了该传感器的传感原理。     

LB膜气体传感器的发展概况

LB膜在走向人工设计智能型分子的过程中,被认为有可能首先在传感器领域取得应用的突破。就LB膜气体传感器目前国内外的发展情况,介绍了几种具有气敏特性的LB膜元件,并对今后的发展方向提出了几点建议。