Preparation And Application Of Visible Electrochromic Hydrogel Dual-mode Sensor With Multiple Stimulus Responses

Stimulus-responsive hydrogels,"intelligent"materials that perceive external stimuli and convert them into human-machine recognition response signals,have become a rising star in the field of advanced functional materials.It has broad application prospects in emerging fields such as soft robots,bionic electronic skins,biomedicine,and wearable electronic devices.With the development of automation and intelligence of sensing systems,traditional sensors based on single stimulus response hydrogels cannot accurately capture various forms of environmental information（light,electricity,temperature,etc.）,so they cannot realize multi-mode sensing applications of single functional integrated devices in complex environments.At the same time,traditional sensors are mostly based on the output form of electrical signals to achieve human-computer interaction,which inevitably requires a bulky and expensive electrical signal recognition and reception port.They lack an intuitive interactive color visualization display system,which undoubtedly limits their practical applications in stress warning,portable wearable devices,information anti-counterfeiting and other scenarios.Therefore,in view of the aforementioned issues faced by sensors,it is urgent to develop and establish a visual sensor that integrates multi-mode sensory response system.This paper integrates and couples multiple stimulus systems such as electrochromic（EC）,supramolecular photoconductive host-guest recognition,and piezoresistive sensing into a single complex device,which are self-assembled into an integrated sensor with interactive visualization and multi-dimensional stimulus perception.The specific research contents are as follows:1.Self-healing visible hydrogel dual-mode sensor with piezoresistive and electrochromic dual stimulus response system.This chapter first utilizes the inherent and synergistic properties of the ternary components of PVA,borax,and IL to prepare a new type of material with good optical properties（T>90%）,excellent conductivity(σ=1.88 m S cm^-1),excellent self-healing ability and good piezoresistive properties of PVA-borax-IL hydrogel electrolyte for construction of a strain sensing platform.Meanwhile,an ultra-low energy consumption VFECSS is assembled by integrating mechanical strain and EC dual-mode sensing systems.The VFECSS shows excellent optoelectronic performance,including low coloring voltage（-0.6 V）,high coloration efficiency(510 cm² C^-1),and good cycle stability（decay inΔT%after 3000 cycles:6.9%）,ultra-low energy consumption(168μW cm^-2),etc.,and under external bending strain stimulation,through self-interactive and controllable visual signals（colorless?green?pink）,achieving visual and non-invasive monitoring with fast and reliable behavior of complex human activities.2.Photoelectric dual-mode supramolecular self-assembly visible hydrogel sensor integrating host-guest molecular recognition.This chapter utilizes the photoconductive host-competitive guest interactions between hostβ-CD and guest photosensitive AzoSO₃H and Fc DMA with different binding capacities.The Z/E isomerization configuration transformation of the photosensitive azobenzene unit induced by UV/Vis light to realize the guest exchange behavior at the microscopic molecular level,and thus the process of host-guest photocontrolled dissociation-self-assemble-recombination occurs.According to the specificity of host-guest recognition features,due to the molecular size matching betweenβ-CD and trans-AzoSO₃H is suitable,and in the absence of external stimulation,they will preferentially spontaneously assemble to form inclusion complexesβ-CD?trans-AzoSO₃H.When irradiated with UV～365 nm light,trans-AzoSO₃H undergoes isomerization and converts to cis-AzoSO₃H,and dissociated withβ-CD,and assembly with Fc DMA to formβ-CD?Fc DMA.When irradiated with Vis～440 nm light,due to trans-AzoSO₃H is a dominant guest,it will driveβ-CD?Fc DMA dissociates and recombines with trans AzoSO₃H to formβ-CD?trans-AzoSO₃H.By indirectly adjusting the concentration of free state Fc DMA through the configuration transition of photosensitive AzoSO₃H,the electrochemical behavior characteristics of the system can be controlled by light.Then,a dual-mode sensor is constructed by using the supermolecular hydrogel with integrated light control host-guest recognition and EC multi-dimensional sensor system.The sensor enables the perception of ambient light（UV or Vis）and electrical stimulation through visual signals for human-computer interaction（yellow?green）.The strategy proposed in this work provides new ideas for new intelligent devices to detect ultraviolet radiation,information encryption,and military camouflage and other applications through visual sensing.