The Nanocomposite Ion-Conductive Wrinkled Hydrogels For Cardiac Electrophysiological Sensing Detection

BackgroundMyocardial infarction(MI)is one of the most leading causes for death worldwide,However,the methods available for cardiac electrophysiological detection are very limited.The current acquisition of cardiac electrophysiological signals is mainly achieved by some bulky and non-in situ methods,which have certain limitations,such as ECG lacks the ability to detect in real time,the electrodes in electrophysiological labeling systems are susceptible to immune rejection,and the modulus of electrodes is mismatched with cardiac tissue,which may be a burden to the heart in the long term.The progress in flexible electronics has facilitated the realization of continuous and high-fidelity physiological signal monitoring;in particular,implantable flexible strain sensors have shown unique advantages in real-time and in situ monitoring of physiological signals such as cardiac contraction,blood flow,and muscle motion due to their high strain/stress sensing capability and biomechanical adaptability.In recent years,although many soft bioelectronic systems with high strain/stress sensing capabilities and biomechanical conformability have been developed,most of reported literatures focused on the improvement of ECG electrodes and still not involving in the pathological state of the heart monitoring.Furthermore,there is an irreconcilable balance between biocompatibility and sensitivity.Although a lot of publications were devoted to pursue and screen implantable sensors systems taking advantage of lowimmunogenicity or naturally sourced biomaterials,little attention has been paid on the importance of non-specific protein adsorption,which is fundamentally prerequisite for eliminating immune response after in vivo implantation.When the sensor is implanted on the surface of the heart where myocardial infarction occurs,it must ensure that it does not aggravate the original pathological condition and responds to the most realistic physiological conditions.Therefore,it is challenging to develop a strain sensor with high biocompatible and sensitive.ObjectiveTo prepare a flexible strain sensor with high biocompatibility and sensitivity for the detection of cardiac electrophysiological signals.Method1.Hydrogel was prepared by one-step incorporation of the polyacrylamide(PAM)/zwitterionic sulfobetaine-based acrylate monomers(SPE)/N,Nmethylenebisacrylamide(BIS)with a multifunctional cross-linker and nano-reinforcer nanoclay sheets decorated with poly(acrylic acid)-hydroxyethyl methacrylate(PAAHEMA),followed by the characterization.2.In vitro and in vivo experiments were conducted to characterize the biocompatibility of the hydrogel to assess its safety and suitability as an implantable device.3.Detected the sensing performance of wrinkled hydrogel sensor,and explored the mechanism of how wrinkles enhance the sensing performance,then applied it to wearable sensors and the detection of myocardial infarction.Result1.The nanocomposite hydrogel prepared with surface wrinkle microstructure and hierarchical inner microarchitectures showed outstanding mechanical stability,as well as the elastic modulus and electrical conductivity which match with biological tissues.2.Nanocomposite hydrogels exhibit significant resistance to protein adsorption,which reduces the level of immune response,resulting in a resistance to the formation of fibrous capsules and conferring high biocompatibility to the hydrogel.3.The multilevel of surface wrinkle microstructure and hierarchical inner microarchitectures provides the hydrogel with superior mechanical-electrical sensing capability,allowing it to sense large and small deformations generated during human movement.4.Based on the high biocompatibility and sensitivity of the nanocomposite wrinkled hydrogel,it can achieve the detection of cardiac electrophysiological signals,distinguish normal and pathological cardiac electrical signals,and also locate the specific location where myocardial infarction occurs.ConclusionHerein,we have developed a highly stretchable,biocompatible,sensitivity,remarkable protein resistance and nanoclay-composite reinforced ionic-conductive hydrogel by using a one-step freeze polymerization technique with surface wrinkle microstructure and hierarchical inner microarchitectures,and applied it to wearable and implantable sensor based on these characteristics.This hydrogel sensor could not only monitor a full range of human motion,but also can be used to collect electrophysiological signals of the heart and locate the area where myocardial infarction occurs.