Self-Adhesive Conductive Nanocomposite Hydrogels And Their Wearable Therapeutic Properties

As a matrix material for flexible wearable sensors,the hydrogel shows great potential for development and commercial application in the field of wearable medical treatment due to its unique biological tissue similarity and good biocompatibility.However,traditional hydrogel-based sensors with poor sensing performance and relatively single function are not only unable to perform high performance monitoring of broad-range human activity signals and electrophysiological signals,but also difficult to integrate medical diagnostic and therapeutic functions at the same time.These are attributed to the limited mechanical strength,low sensing performance,poor self-healing and self-adhesive properties of conventional hydrogel.Therefore,the thesis intends to develop self-healing and self-adhesive multifunctional conductive nanocomposite hydrogel to be assembled as flexible sensors for human health monitoring and wound treatment through introducing the emerging twodimensional nanomaterial MXene nanosheets as conductive fillers.1.Firstly,the as-prepared MXene nanosheets were efficiently incorporated into the hydrogel network constructed from borax,chondroitin sulfate aldehyde(OCh S)and gelatin through system selection and molecular design to obtain a MXene/OCh S-Borax/Gelatin conductive nanocomposite hydrogel based on supramolecular interactions.The supramolecular interactions in the system,such as the dynamic borate ester bonds,the dynamic imine bonds formed by Schiff bass reactions and the hydrogen bonds,endowed conductive nanocomposite hydrogel with rapid self-healing property.In addition,the conductive nanocomposite hydrogel exhibited significantly enhanced mechanical properties(elongation at break up to about 600% and breaking strength up to 201.74 k Pa),effectively improved electrical conductivity and sensing property due to the incorporation of MXene nanosheets.Meanwhile,the MXene nanocomposite hydrogel showed good biocompatibility and effective antibacterial ability against S.aureus and E.coli(the bacteriostatic rates were 91.4% and 94.9%,respectively).The excellent mechanical properties,electrical conductivity,sensing properties,self-healing properties and biological properties fully support the promising application of conductive nanocomposite hydrogel in flexible wearable sensing and biomedical applications.2.Conductive nanocomposite hydrogel could exhibit repeatable adhesive ability and great compliance to human skin,and could be assembled into a multifunctional flexible wearable sensor for human health monitoring,wearable human-machine interaction and wound hemostasis due to a large number of interaction sites provided by the active groups on the polymer chain.The flexible sensor based on the conductive nanocomposite hydrogel could demonstrate high sensitivity(GF=0.98),wide detection range(0.5-300%)and outstanding stability(～140 times)for strain sensing,which has great application potential in monitoring large-scale movement(wrist,neck and elbow bending)and small-scale movement(radial artery beat and temporomandibular joint movement),as well as detecting cardiovascular diseases or temporomandibular problems.The hydrogel could also be integrated with wireless transmission devices for wearable human-machine interaction,providing an ideal platform for sign language recognition.Meanwhile,conductive nanocomposite hydrogel-based sensors showed higher signal-to-noise ratio(SNR=19.7 d B)and lower skin interface impedance than commercial electrodes,which could sensitively monitor electrophysiological signals,such as electrocardiogram(ECG)signals in running condition and electromyogram(EMG)signals with different muscle activity intensities,contributing to cardiovascular and muscle disease diagnosis,exercise health and rehabilitation training monitoring.Moreover,MXene nanocomposite hydrogel with excellent biocompatibility and reliable antibacterial properties could be used for safe,convenient and efficient wound hemostasis treatment,supplying crucial new ideas to promote personalized healthcare with integrated medical treatment.