Research On Multi-directional Flexible Strain Sensor Based On Liquid Metal

With the popularization and multi-functionalization of smart electronic devices,wearable electronic devices present a huge market prospect.As the detection unit of the wearable device to the external environment or the human body,the flexible strain sensor plays an important role in the development of the wearable device.When monitoring human body parameters and exercise conditions,the flexible strain sensor is usually used to measure the strain changes.The flexible strain sensor prepared based on solid conductive fillers such as graphene,carbon nanotubes and metal nanoparticles is greatly restricted in terms of tensile properties and stability.Liquid metal with high conductivity,high surface tension,deformability and low toxicity becomes the preferred material for preparing flexible strain sensors with high stretchability and high stability.At present,the flexible strain sensor based on liquid metal is sensitive to tensile strain in a single direction,but is not sensitive to tensile strain in multiple directions.However,in the application of wearable electronic devices,it is often encountered that it is necessary to detect tensile strain in multiple directions.Therefore,for wearable electronic devices that need to detect multi-directional tensile strain,the flexible strain sensor that is only sensitive to unidirectional tensile strain has shortcomings.In response to this problem,a multi-directional flexible strain sensor based on liquid metal is proposed in this paper.The sensor uses the characteristic that the tensile strain parallel to the microfluidic channel is more sensitive than that perpendicular to the microfluidic channel,and realizes the detection of multi-directional tensile strain.The main research contents include:(1)Strain detection principle and multi-directional decoupling model of multi-directional flexible strain sensor based on liquid metal;(2)Simulation model of multi-directional flexible strain sensor based on liquid metal;(3)Design and preparation method of multi-directional flexible strain sensor based on liquid metal;(4)Test and analysis of strain characteristics of multi-directional flexible strain sensor based on liquid metal.The research results show that the cross shaped microfluidic sensor designed in this paper has a small size of 30mm×30mm×1.8mm and can detect tensile strain in the range of0-20%strain with a repeatability error of 2.03%.The sensitivity is1.17×10^-2,the linearity is 2.73%,and the hysteresis error is 1.12%.The sensor has high sensitivity and excellent linearity,which can realize accurate measurement of strain.In addition,the repeatability and hysteresis of the sensor are good,so that the sensor can maintain a relatively stable output in the case of multiple measurements and different measurement strokes.Therefore,the multi-directional flexible strain sensor based on liquid metal designed in this paper can realize the stable measurement of multi-directional strain.This research can realize the detection of tensile strain in multiple directions by the flexible strain sensor in wearable electronic devices,which has important scientific research value and practical significance for enriching and perfecting the application of wearable electronic devices.