Prearation And Application Of Conductive Hydrogel-based Wearable Sensors

The hydrophilic structure of hydrogels allows them to hold a large amount of water in their three-dimensional network,enabling them to have good biocompatibility and widely adjustable physical and chemical properties.With the development of science and technology,flexible wearable soft sensors based on conductive hydrogels have attracted considerable attention for their substantial and important applications in human-machine interfacing,ultra-sensitive electronic skins and personal healthcare recording.According to the current research progress of hydrogel-based sensors,this paper introduces two types of hydrogel-based sensors with excellent performance,which are organohydrogel-based sensor with anti-freezing and anti-heating ability,long-lasting moisture,reliable self-healing ability and ultra-sensitive sensing performance and hydrogel-based sensor with self-healing ability,drug controlled release system and ultra-sensitive sensing performance.The detailed work is as follows:1.The nanocomposite organohydrogel is prepared from the conformal coating of functionalized reduced graphene oxide(rGO)network by the hydrogel polymer networks consisting of polyvinyl alcohol(PVA),phenylboronic acid grafted alginate(Alg-PBA),and polyacrylamide(PAM)in the binary EG/H2O solvent system.We report the fabrication of an organohydrogel-bsed epidermal sensor with anti-freezing and anti-heating ability,long-lasting moisture,ultra-sensitive sensing performance and reliable self-healing ability.The influences of the concentration of reduced graphene oxide,the amount of acrylamide and ethylene glycol on the pressure-sensitive and mechanical performances were investigated.After that,the epidermal sensors were attached to the human body for detecting a series of human activities,such as finger bending,pulse,Morse code pressing,under cold and hot conditions respectively.The results demonstrated that the obtained organohydrogel exhibited high sensitivity(0.1122 kPa-1),wide detection range(0.05 kPa-100 kPa),fast response speed(0.10 s)and stable sensing performance of more than 500 cycles,even at extreme conditions(-40? or 60?).In addition,the epidermal sensor can keep excellent sensing and mechanical properties even if kept in normal temperature for 20 days.The epidermal sensor based on organohydrogel can also be assembled into electronic skin with wireless equipment for wireless transmission and monitoring of human activities.It shows that it paves the way for the fabrication of ultra-sensitive wearable sensors with excellent temperature tolerance,long-lasting moisture,and self-healing capability for potential versatile applications in smart electronic skins,healthcare monitoring and human-machine interfacing.2.The flexible pressure-sensitive epidermal sensor was fabricated by adding the conductive nanocomposite MXene to a hydrogel system composed of polyvinyl alcohol,borax,and low melting point agarose.Simultaneously,the antibacterial drug moxifloxacin hydrochloride(MOX)was added to the hydrogel,and the controlled release drugs could be achieved by the near-infrared photothermal effect of MXene and the easy melting characteristics of agarose.The physical properties,sensing properties under different deformation,self-healing properties and antibacterial properties in vitro of the sensors were investigated.The results showed that the epidermal sensor has an extremely high strain sensitivity factor(0.05 kPa-1).Meanwhile,the epidermal sensors maintained an excellent self-healing efficiency,which could be healed more than 85%in 15 minutes.In addition,under the irradiation of near-infrared light(880 nm,1 W),the sensor could release the bacteriostatic drug MOX to achieve timely bacterial inhibition of the wound.The sensors could be coupled with wireless transmission equipment to monitor various activities of the human body.If there is a wound on the human skin,the hydrogel can be transferred to the wound and illuminated with near-infrared light to release the bacteriostatic drug MOX.It confirmed the applicability of this hydrogels in the fields of human motion monitoring,intelligent medical treatment and wound treatment.