Hydrogel-wet tissue adhesive systems hold great promise for biomedicine and bioelectronics,yet their practical appli-cation is severely restricted by interfacial failure in complex physiological environments.Such adhesives frequently suffer from fatigue,delamination and slippage well before reaching their theoretical adhesive strength,proving that conventional strength-based evaluation cannot reflect their actual stability.Classical fracture mechanics and viscoelastic adhesion theories describe failure through energy release rate,work of adhesion,and rate-dependent fracture energy,but they commonly incorpo-rate dissipation into an effective fracture parameter and do not explicitly resolve how energy is stored at the interface,trans-ferred into the bulk,and dissipated across the hydrated interface-bulk continuum.This review organizes current hydrogel-tis-sue adhesion strategies into a three-tier energy-regulation framework comprising interfacial buffering,interface-to-bulk energy transfer,and bulk dissipation.The framework is connected to measurable quantities,including energy release rate,effective frac-ture energy,fatigue threshold,interfacial stress concentration,transfer efficiency,and hysteresis loss,to provide semi-quantita-tive guidance for material design and comparison.Key failure modes,representative structural and molecular strategies,and a practical characterization workflow are discussed.Remaining challenges in parameter identification,cross-scale constitutive mod-eling,and in vivo validation are outlined.
Stretchable bioelectrodes need both conductivity and deformation stability,but the conductive pathways of tradi-tional rigid materials are prone to instability during stretching.In this study,polyaniline coated graphite powder(PANI@G)core shell fillers were constructed through the in situ oxidative polymerization of aniline and were sprayed onto a styrene-ethylene/butylene-styrene block copolymer(SEBS)substrate to prepare stretchable conductive films.The PANI coating layer improved the connection between graphite lamellae through interfacial interactions among nitrogen containing groups,oxy-gen containing functional groups,and conjugated structures.As a result,the film retained approximately 89%of its initial cur-rent at 75%strain,and the current drift was only 2.3%during 126 min of continuous stretching at 50%strain.The film was fur-ther patterned into lightweight flexible electrodes and realized electrical signal acquisition induced by electrical stimulation,pro-viding an effective strategy for wearable flexible electrodes.
Progress in understanding optoelectronic properties of the two-dimensional(2D)transition metal carbides and nitrides(MXenes)is hindered by a dearth of exploring novel intrinsic semiconductor materials from MXene families.Here,we prepared 2D Ti4N3 MXene nanoflakes via the molten salt etching method,which was then employed to fabricate a flexible broad-band near-infrared(NIR)photodetector.The assembled Ti4N3 MXene based photodetector exhibits a stable response to the lasers of 808,852,915,980,and 1060 nm.Under high-power IR illumination,the device deviates entirely from conventional posi-tive photoconductivity,displaying an anomalous superlinear negative photoresponse with a power-law exponent of α=1.54 and a response time of～0.7 s.The negative photoconductivity behavior of the Ti4N3 MXene based devices is driven by a robust photothermal-ionotronic coupling mechanism:the intense IR-induced local heating heavily disrupts the interfacial hydrogen-bonding networks,triggering an Arrhenius-type non-linear desorption of confined water and protons that effectively discon-nects the ionic conduction pathways.This work provides fundamental insights into the photothermal-dominated carrier and ion dynamics in 2D materials,paving the way for next-generation optoelectrical devices and neuromorphic sensory systems.
Accurate and quantitative evaluation of human fatigue status is of crucial importance to safe outdoor operations and personal health management.Electroencephalography(EEG)technology offers a non-invasive,rapid and high-accuracy feasi-ble solution,yet it still faces challenges such as large device volume and unstable electrode-skin interface.In this work,we pro-pose a wearable intelligent EEG platform for real-time monitoring and assessment of human fatigue status.A flexible dual-chan-nel(FP1,FP2)EEG patch was fabricated in flexible PET film by coupling screen-printed carbon powder/graphene oxide elec-trodes with a biocompatible polyacrylic acid/polyvinyl alcohol(PAA/PVA)hydrogel.Among them,the composite carbon struc-ture and the hydrogel provide a low interfacial impedance(98.3 Ω·cm2@1 kHz),skin-matched mechanical modulus(3.5 kPa)and a skin-conformal(296 kPa adhesion strength)electronic interface,respectively,laying a solid foundation for acquiring high-quality and stable EEG signals.Furthermore,a smartphone APP was developed to wirelessly operate the EEG platform,as well as to transmit and process real-time EEG data.To verify the effectiveness,a multi-state simulation-induced fatigue test was conducted.The results demonstrate that the proposed EEG platform can detect the EEG spectrum and conduct rhythmic classifi-cation processing,in which the θ/β value(>1.5)could serve as a reliable indicator of fatigue,enabling quantitative evaluation and early warning of human fatigue.
In recent years,position-sensitive detectors(PSDs)have found widespread application in displacement measure-ment,optical measurement,imaging,and laser communication,owing to their high spatial resolution and rapid response capa-bilities.However,the performance and operating mechanisms of perovskite-based PSDs remain insufficiently elucidated.In this work,we fabricated a high-sensitivity self-powered PSD based on a ZnO/P(VDF-TrFE)-CH3NH3PbI3(MAPbI3)heterojunction.Sys-tematic optimization revealed an optimal P(VDF-TrFE)doping concentration of 5 mg/mL,enabling the device to achieve a remarkable positional sensitivity(PS)of 307.03 mV/mm with a minimum nonlinearity of 1.02%.Furthermore,the intrinsic pyro-electric property of P(VDF-TrFE)induces a significant pyroelectrically enhanced lateral photovoltaic effect(LPE),boosting the PS to 511.33 mV/mm—an enhancement of 166.5%.The heterojunction PSD maintains effective operational performance over an electrode spacing range of 0.5-2.2 mm.While the LPE response declines with increasing spacing,a considerable pyroelectric effect(PE)-enhanced PS of 70.67 mV/mm is retained even at 2.2 mm.Importantly,we demonstrate multi-wavelength imaging by exploiting both the inherent LPE response and its pyroelectrically enhanced counterpart,with imaging intensity tunable via electrode spacing control.This study provides crucial insights into the LPE behavior of the heterojunction and systematically clar-ifies the mechanism by which the PE modulates device performance and imaging capabilities.
