Fabrication And Performance Investigation Of Stress/Strain Sensors Based On Low-Dimensional Materials

The improvement of the traditional stress/strain sensors is getting smaller and smaller in sensitivity,response time,detection range,stability and service life.The novel strain/strain sensors require the device to be flexible,stretchable and so on.In this paper,several novel stress/strain sensors are developed by means of the micro/nano technology as a means based on low-dimensional materials.Through the controllable preparation and performance optimization,high-performance and low-cost wearable sensing devices are fabricated.Furthermore,the applications of intelligent wearable sensing devices are promoted.The main research work of this paper includes the following six aspects.By using ZnO(Zinc Oxide)nanowires and MgO(Magnesium Oxide)tunneling layer,a high switching ratio of the pressure sensor is built.The pressure sensor features switch ratio of 7.2×105,the sensitivity of 7.1×104 gf-1,the response time of 128 ms and the detection range from 3.2 gf to 27.2 gf.This is mainly due to the interaction of the tunneling effect of MgO with the piezoelectric effect of ZnO.Through a pencil brushing method,a low-cost flexible paper-based strain sensor is developed.The response time is 110 ms.The sensitivity is 536.The minimum resolution strain is 0.13%.The basic resistance drift change of the strain sensor is about 10%after 10,000 times of bending strain tests.The principle of the sensor is mainly based on the change of the overlap areas between the graphite sheets and the sizes of cracks.A large area of high-performance flexible strain sensor is rapid prepared by stencil printing method.The response time of the device is 22.3 ms.The sensitivity is 804.The minimum resolution strain is 0.038%.After 10,000 bending tests,the change value of basic resistance is within 2%.The principle of the sensor is mainly based on the change of the form of cracks,which impacts the transmission path of electrons in the graphite film.A waterproof wearable strain sensor based on gold nanoparticles is constructed by the DC(direct current)sputtering method.The device has the service capability of>18000 tests and the response time of<20 ms.the device's waterproof capacity reaches the level of IPx7.By studying the effect of surface morphology on the performance of the device,we discovered that the surface microstructure,including mesh number and absolute average height,will modulate the sensitivity of the device.A stretchable fiber-based strain sensor is prepared by hydrothermal method.The theoretical sensing model of the device is established.The response time is 38ms.The sensitivity is 15.2.The sensing principle is mainly due to the change of micro-contact between ZnO nanowires.The sensor features soft,lightweight and fibrous.A highly sensitive stretchable strain sensor is fabricated by means of patterned method.Device's sensitivity is up to 150,000,which is increased to 136 times than that of the device without microstructure.It also has the capability of more than 35,000 times strain testing.The device has important application prospect in intelligent wearable equipment,electronic skin and so on.A series of technology is proposed to optimize the design of high-switching pressure sensor,cuttable strain sensor,self-waterproof flexible strain sensor and high sensitivity stretchable strain sensor by optimization and design of energy band and surface microstructure.It provides a new way for the intelligent wearable electronic devices for further development and application.A series of technology is proposed to optimize the design of high-switching pressure sensor,cuttable strain sensor,self-waterproof flexible strain sensor and high sensitivity stretchable strain sensor by optimization and design of energy band and surface microstructure.It provides a new way for the intelligent wearable electronic devices for further development and application.