The Research Of Flexible Sensor Technology Based On Ink-Jet Printing

With the continuous development of the internet of things,intelligent wearing and modern logistics industry,the demand for intelligent instruments,wearable devices and flexible electronics is growing fast.The essence of the internet of things is to connect objects together through radio communication and electronic tags.As an important component of the internet of things,the demand for sensors has increased dramatically.Therefore,it is very important to find a manufacture technology of sensor with low cost,large production and esay to be integrated.The sensor can convert various data,such as temperature,humidity,sound,pressure and other information into specific electrical signals to achieve the design concept of "Internet of Everything".In terms of the manufacturing process of traditional silicon,it is complicated to product a sensor,and it has become increasingly unable to meet the design and production requirements.In order to meet the needs of the intelligent wear,objects interconnection and transportation monitoring,new sensor manufacture process must be explored to product light and flexible sensors.The new manufacture process should be sample and cheap.And the purpose of this thesis is to realize temperature monitoring and humidity monitoring with flexible sensor.According to the actual application requirements of the sensor,nano-silver conductive ink is used as the printing material,and polyimide(PI)film is used as the flexible substrate material,we product the sensor on the flexible substrate by ink-jet printing technology and sintering process.The process of producting temperature and humidity sensor has been successfully explored.Meanwhile,metallization processes based on inkjet printing technology is also completed.The characteristics of the temperature sensor sensitivity,temperature hysteresis and measurement range are studied.The test results show that the temperature sensor product by inkjet printing technology has good temperature linearity and sensitivity in the range of-25°C-125°C.The proposed measurement of circuit effectively solves the problem of sensor temperature quantification and reduces the system measurement error.The humidity sensor have good performance in the humidity range of 20% RH~90% RH.In the experiment,we use resin material to cover on the surface of the metal plate to prevent it from being corroded and oxided.The response time of humidity sensor is improved by MATLAB simulation.And the analog conversion circuit realizes the quantization function of the capacitive humidity sensor.We use inkjet printing technology to product flexible sensors and simplify complex traditional process steps.The integrated system of various sensors is made on the PI substrate,and the design goal on high efficiency,low cost and large production of the flexible sensor is realized.Finally,we combine the flexible sensors and RFID technology together and provide a design for wireless transmission of sensor data,which enhances the scalability of the label.And it will make the application field of flexible sensors wider.