Preparation And Properties Of Hydrogel Strain Sensors Based On Dual Structure

Nowadays,with the in-depth research on hydrogels,the properties of hydrogels such as conductivity,p H responsiveness,and temperature and humidity sensitivity have been discovered.Conductivity is an important property that enables hydrogel to be used as a flexible sensor to sense changes in human movement.However,current conductive hydrogels have problems such as weak mechanical properties,low-temperature inactivation,and limited strain detection range,which restrict the wide-ranging use of hydrogels.In order to solve these problems,it is of great significance to prepare a hydrogel with high mechanical properties,low temperature resistance,and wide strain detection range.In the first part of this paper,an anti-freeze double-layer hydrogel strain sensor with excellent mechanical properties is introduced.The polyaniline(PANI)was introduced into the glycerol(GL)/water system hydrogel based on polyvinyl alcohol(PVA)as the conductive layer,and the non-conductive layer was composed of PVA/GL.Because the long chain structure of PANI is difficult to diffuse in the hydrogel,there is an obvious conductive difference between the two layers of hydrogels.The PVA hydrogel with good biocompatibility can contact the skin directly,which brings more accurate sensing signal for the hydrogel sensor.At the same time,due to the presence of glycerin,the double-layer hydrogel sensor can still maintain good flexibility and excellent electrical conductivity at low temperatures,which greatly expands the range of use of the sensor.In the study,we found that the strain monitoring range of the hydrogel sensor was usually less than 500%,and the viscosity and toughness could not be combined at the same time.Although it was sufficient for routine human motion monitoring,it was difficult to cope with the monitoring in some special environments.Therefore,in the second part,we modified the arrangement of the double-layer hydrogels,inspired by the helical structure,designed and prepared a dual-structure hydrogel sensor combining high toughness and high modulus.The design of the structure of the hydrogel strain sensor not only provides a new direction for the preparation of hydrogel sensor,but also has potential application prospects in the fields of artificial intelligence,human-computer interaction and wearable devices.