Research On Piezoelectric Tactile Sensor Based On ZnO Nanorods

Piezoelectric tactile sensors have attracted much attention because of their wide application prospects in human-computer interaction,medical diagnosis,robot hand,electronic skin and other fields.Tactile sensors with high sensitivity,high resolution,fast response,high flexibility and high reliability are currently one of the research hotspots at home and abroad.In this paper,aiming at the contradiction between the high sensitivity and high elasticity of piezoelectric tactile sensors,ZnO nanorods(NRs)prepared by low-cost hydrothermal method are used as the sensitive layer.Based on the theory of piezoelectric effect of ZnO NRs,a high-sensitivity and highly flexible elastic piezoelectric tactile sensor based on ZnO NRs was designed and manufactured.Theoretically and experimentally conducted a systematic study and discussion.The main work and results of this paper are as follows:(1)The main factors affecting the piezoelectric effect of ZnO NRs and their dependence were analyzed by COMSOL finite element software modeling and multi-physical field coupling solution.It is found that the output piezoelectric voltage of ZnO NRs is positively correlated with the piezoelectric constant and length-diameter ratio.Under the action of different forces with the same amplitude(square wave,sine wave,triangular wave),the square wave force presents the maximum output piezoelectric voltage.(2)Using PDMS as the substrate and sputtering ZnO film as the seed layer,the effects of seed layer thickness and AuNPs on the characteristics of hydrothermal growth of ZnO NRs were studied.The experimental results showed that the thickness of seed layer ranged from 22.1 nm to 80.2 nm,and the crystral size first increased and then decreased with the increase of the thickness,but the thicker the seed layer,the better the c-axis orientation and the better the crystallinity.With the increase of AuNPs content,the radial size and height of ZnO NRs increased first and then decreased.The main reason for this phenomenon is that the promotion effect of AuNPs on the growth of ZnO NRs competes with the compressive stress in the film.(3)The tactile sensor units and arrays based on ZnO NRs were prepared to characterize the sensor characteristics.It is found that the output piezoelectric voltage of the sensors with different fabrication processes increases with the increase of pressure,and it has a good linearity in the range of 0-1 N.The thickness of seed layer has a great influence on the sensitivity of the sensor,among which the sensor with the seed layer thickness of 80.2 nm has the maximum sensitivity,with the value of 524.5 m V/N.The AuNPs content in the precursor also had a significant effect on the sensor sensitivity.The device with AuNPs content of 100 ?L(seed layer thickness of 80.2 nm)had the highest sensitivity with a value of 1424.12 m V/N.The results show that a small amount of AuNPs can promote ZnO piezoelectric effect,but too much AuNPs can reduce the spontaneous polarization and length-diameter ratio of ZnO NRs,which leads to the reduction of piezoelectric effect.(4)The piezoelectric response characteristics of a sensor doped with 100 ?L AuNPs in various specific scenarios were studied.The results show that the sensor has excellent stretching and bending functions,can work stably at different frequencies,and can distinguish the roughness and track of objects,can also achieve 8-unit force mapping.Related application research shows that the ZnO NRs tactile sensor is expected to find applications in electronic skin,robotic hand and other fields.