Preparation And Application Of High-performance Bio-based Hydrogel Flexible Sensor Devices

With the development of flexible sensor devices,wearable flexible sensor devices need to meet the requirements of low modulus,durability and stability.Hydrogel has the advantage of low Young’s modulus close to the modulus of human skin and its internal water environment can load other functional substances.Compared with other organic elastomer,it has more research and application value.At present,based on the existing active conductive materials and hydrogel network design,the mechanical properties and electrical conductivity of hydrogel sensors often check and balance each other.In addition,under the background of the rapid development of natural polysaccharide materials and the need for non-toxicity and degradability of flexible sensors,it is of great significance to use natural polysaccharide binding polymer network to construct a bio-based physical crosslinking hydrogel network with good electrical conductivity and mechanical properties.Then further consider how to use the biobased network to combine other functional components to construct a transparent hydrogel with composite sensing functions,so that the hydrogel flexible sensor device will develop from a single function to a composite function.Therefore,this paper designs a series of bio-based crosslinked networks and uses them to prepare functionalized hydrogel flexible sensors.(1)A novel cyclodextrin topological nanoparticles(TNPs)were constructed.These TNPs were found to possess crosslinking capabilities and the corresponding TNPs-crosslinked hydrogels showed excellent mechanical performances with a high stretchability of 1860% and stress of 180 k Pa and good anti-fatigue abilities.These hydrogels could be readily recycled and used for modular assembly and disassembly in various shapes and could serve as flexible strain sensors to monitor human activities with a sensing range of 0～1800%,controllable sensitivity,and good fatigue resistance.These topological nanoparticles could inspire the design of novel physical crosslinkers for novel flexible strain sensors,tough and self-healing hydrogels,and soft robotics.(2)A sustainable physical crosslinking agent,waterborne modified chitosan(m PEG-SACs)was designed.Multi-functional sensing organic hydrogels with excellent mechanical properties were constructed by using the strong physical interactions of m PEG-SA-Cs,including the entanglement of polymer chains and the strong hydrogen bonding with the gel network,as well as the chemical crosslinking of the gel itself.Since glycerin and salt solution were used as gel dispersant,it could also be used as a multifunctional flexible sensor.It had a good sensing range of 0～1200%,excellent durability(resistant to cyclic stretching more than1000 times,strain 600%)and anti-freezing properties(stretching to 800% at-40 ℃).Based on these advantages,Cs EMFS organic hydrogels were used as a strain,temperature and humidity sensor,and a wireless sensor system was also constructed for wireless sensor testing.