Study On The Preparation And Properties Of Tetraaniline-Modified Polyvinyl Alcohol Organohydrogel Fiber-Shaped Strain Sensor

In recent years,flexible wearable strain sensors,as electronic devices that convert strain into electrical signals,have gained widespread use in the fields of human motion monitoring,health management,and human-computer interaction.Hydrogel materials with biocompatibility,adjustable elasticity,and certain electrical conductivity are commonly used as substrates to integrate soft,highly elastic,and sensitive strain sensors.However,hydrogel-based strain sensors face challenges such as poor mechanical stability,low sensitivity and long response time.In comparison,the organohydrogel fiber has excellent mechanical properties and good stability under extreme environment,so it has certain advantages in the preparation of strain sensors.This research is focused on two specific aspects:（1）Due to uniform distribution of ions and the reduced amount of charge carriers at subzero temperature,organohydrogel fibers-based sensors show the undesirable sensitivity at subzero temperature.A competitive proton capture strategy has been proposed to address this issue.This approach involves incorporating tetraaniline（TANI）,the shortest structural unit of polyaniline（PANI）,into polyvinyl alcohol（PVA）to construct high-sensitivity anti-freezing wearable strain sensor organohydrogel（PTOH）fibers.PTOH fibers exhibit exceptional sensing properties at-40^oC and possess a sensitivity factor of 24.6 at 200-300%strain,attributed to the difference between TANI rigid chain and PVA flexible chain as well as the enhanced activation energy of proton transfer resulted from the formed hydrogen bonds between TANI and PVA chains in organohydrogel fibers.Additionally,those hydrogen bonds endow the PTOH fibers with superior tensile strength（1.96 MPa）and toughness(8.0 MJ m^-3).Consequently,strain sensors fabricated from PTOH-3 fibers and knitted fabrics demonstrate rapid responsiveness and high sensitivity.（2）The organohydrogel strain sensor exhibits a poor performance in its detection limit,making it difficult to detect minute strains such as pulse,heartbeat,swallowing,voice and other practical applications.A strategy combining wet spinning with in-situ self-assembly has been proposed to address this undesirable performance.An organohydrogel fiber（PTOHF）comprising a PVA network,TANI nanofibers,ethylene glycol（EG）and H₂O has been synthesized.The nanofiber structure of TANI not only enhances the rigidity and mechanical strength of PVA organohydrogels（POHF）,but also imparts an ultra-low detection limit（0.01%）to PTOHF.Furthermore,PTOHF exhibits excellent stability with electrical hysteresis less than 1%under small deformation.