柔性力敏薄膜及阵列压力传感器的研究

发布时间：2018-06-21 09:58

本文选题：柔性力敏薄膜 + 单点压力传感器　；参考：《电子科技大学》2017年硕士论文

【摘要】：柔性压力传感器是用来测量感知各种复杂表面的压力实时变化的柔性传感电子器件,一般由柔性衬底材料,柔性电极,柔性力敏薄膜组成,按照组合方式主要分为单点式压力传感器和阵列式压力传感器。单点式压力传感器主要针对点目标,可用于实时精确测量某一个单点微小位置的压力变化情况,柔性阵列式压力传感器主要针对面目标,适用于检测复杂物体表面所受到的压力大小和压力分布状态。本论文针对构成压力传感器核心部分的柔性力敏薄膜进行了深入研究,设计制作了基于TPU(热塑性聚氨酯)和高导电炭黑复合材料的柔性力敏薄膜,并基于该柔性力敏薄膜设计制作了柔性单点压力传感器和阵列压力传感器。研究了改善压力传感器灵敏度、稳定性、重复性、响应时间、抗蠕变性能等的工艺方法。然后设计制作了相应的采集调理电路,最后利用Labview测控软件开发工具开发了相应的上位机软件,实现了对传感器信号的采集、标定、优化、处理、存储和显示。本论文首先探究了0-3构型的柔性力敏薄膜复合材料的导电机理,包括常用的导电复合材料加和效应:渗流模型理论和隧道效应理论,以及导电复合材料乘法效应:压阻效应(正压阻效应和负压阻效应),概况分析了力敏薄膜内部导电网络的形成与破坏过程;然后对力敏薄膜的各种性能表征方法进行了介绍。进一步的,通过具体实验研究了柔性力敏薄膜的制备工艺过程,包括柔性基体材料的选择,导电物质的选择和其他纳米改性材料的选择,以及有机溶剂的选择。本文实验中采用的是热塑性聚氨酯(TPU)作为基体材料,高导电炭黑作为导电物质,ITO纳米颗粒作为改性材料,用流延涂覆法制备力敏薄膜。研究了不同炭黑掺杂浓度下力敏薄膜的初始电阻变化,根据渗流模型理论找出该导电复合材料的渗流阈值为10%wt,渗流区域为10%wt-12%wt;然后在渗流区域附近制备了几种不同掺杂浓度下的力敏薄膜并分别测试其压阻性能,找出了TPU与高导电炭黑的最优化配比浓度为12%wt;最后利用各种性能表征手段对力敏薄膜的表面形貌、灵敏系数、线性度、重复性、响应时间等性能参数进行了测试。为了改善导电材料在基体材料的分散效果和抗蠕变性能,比较了掺杂ITO纳米颗粒与SiO2纳米颗粒对改善力敏薄膜重复性和一致性的影响。通过上述工作制备了性能良好的厚度为200μm的柔性力敏薄膜以及单点压力传感器、弯曲度应变传感器和4×4阵列式压力传感器,灵敏度和响应时间(㩳100ms)都得到极大优化,具备了对压力变化实时动态监测的能力。最后分别设计制作了单点和阵列压力传感器的后端信号调理电路和上位机软件,将力敏薄膜的电阻变化转化为易于测量的电压变化。单点压力传感器后端电路利用反相运算放大器mcp6001将传感器电阻变化转化为电压信号,经AVR单片机内置的模数器转换后由串口发送到上位机进行数据处理和显示;阵列压力传感器后端调理电路利用AVR单片机控制CD4051数字模拟开关实现了对阵列式压力传感器的行列扫描,将多点问题转化为易于处理的单点问题,采集的电压数据经串口发送到上位机进行数据处理和显示。针对阵列电阻测量中不可避免的电阻交叉耦合问题,提出了通过改进传感器结构来消除阵列压力传感器各传感单元之间交叉耦合问题的新方法。最后利用Labview测控开发软件开发了对应的上位机软件,实现了对传感器信号的读取和显示。
[Abstract]:Flexible pressure sensor is a flexible sensing electronic device used to measure real time change of pressure in various complex surfaces. It consists of flexible substrate material, flexible electrode and flexible force sensitive film. According to combination, it is divided into single point pressure sensor and array pressure sensor. Single point pressure sensor is mainly aimed at point order. The standard can be used to measure the pressure change of a single point position in real time. The flexible array pressure sensor is mainly aimed at the surface, and is suitable for measuring the pressure and pressure distribution of the surface of a complex object. This paper has studied the flexible force sensitive film which is the core of the pressure sensor. A flexible force sensitive film based on TPU (thermoplastic polyurethane) and high conductive carbon black composites was designed and fabricated. A flexible single point pressure sensor and an array pressure sensor were designed and fabricated based on the flexible thin film. The process to improve the sensitivity, stability, repeatability, response time and creep resistance of the pressure sensor was studied. And then the corresponding collection and adjustment circuit is designed and produced. At last, the corresponding PC software is developed by using the Labview software development tool, which realizes the acquisition, calibration, optimization, processing, storage and display of the sensor signals. This paper first explores the conductive mechanism of the flexible force sensitive thin film composite with 0-3 configurations. The addition and effect of conductive composite materials: seepage model theory and tunneling effect theory, and the multiplicative effect of conductive composite material: piezoresistive effect (positive piezoresistive effect and negative pressure resistance effect), the formation and failure process of the internal conductive network of the force sensitive film is analyzed, and the various performance characterization methods of the force sensitive film are introduced. One step, the preparation process of flexible force sensitive thin films was studied by specific experiments, including the selection of flexible matrix materials, selection of conductive materials and the selection of other nano modified materials, and the selection of organic solvents. In this experiment, the thermoplastic polyurethane (TPU) was used as the matrix material, and the high conductive carbon black was used as the conductive material. ITO nanoparticles are used as modified materials to prepare the force sensitive thin film with a flow coating method. The initial resistance changes of the force sensitive film under different carbon black doping concentration are studied. The percolation threshold of the composite is 10%wt, and the percolation zone is 10%wt-12%wt. Then several different doping is prepared near the seepage area. The piezoresistive performance of the force sensitive film under the concentration was tested and the optimal ratio of TPU to high conductive carbon black was found to be 12%wt. Finally, the properties of the surface morphology, sensitivity coefficient, linearity, repeatability and response time of the film were tested by various performance characterization methods. In order to improve the conductive material in the matrix material The effects of the dispersion and creep resistance of the material were compared. The effects of doped ITO nanoparticles and SiO2 nanoparticles on the reproducibility and consistency of the Li Min film were compared. Through the above work, a flexible force sensitive film with a good thickness of 200 mu and a single point pressure sensor, a flexural strain sensor and a 4 x 4 array pressure sensor were prepared. The sensitivity and response time (? 100ms) have been greatly optimized and have the ability to monitor the pressure change in real time. Finally, the back end signal conditioning circuit and the host computer software for single point and array pressure sensors are designed and made respectively. The resistance change of the force sensitive film is converted to the voltage change easily measured. The back end circuit uses the inverse operational amplifier mcp6001 to convert the change of the sensor resistance to voltage signal, and transmits it to the upper computer through the serial port after conversion of the built-in analog digital device of the AVR single chip microcomputer to carry out data processing and display. The array pressure sensor backend circuit uses the AVR single chip computer to control the CD4051 digital analog switch to realize the array column. The multi point problem is transformed into a single point problem which is easy to be handled by the column scan of the pressure sensor. The voltage data collected is sent to the host computer for data processing and display by serial port. In view of the unavoidable resistance cross coupling problem in the array resistance measurement, an improved sensor structure is proposed to eliminate the transmission of the array pressure sensors. A new method of cross coupling between sensing elements is used. At last, the corresponding PC software is developed by using Labview test and control development software, which realizes the reading and display of the sensor signals.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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