Hydrogel-Integrated Multimodal Response as a Wearable and Implantable Bidirectional Interface for Biosensor and Therapeutic Electrostimulation

Abstract

A hydrogel that fuses long-term biologic integration, multimodal responsiveness, and therapeutic functions has received increasing interest as a wearable and implantable sensor but still faces great challenges as an all-in-one sensor by itself. Multiple bonding with stimuli response in a biocompatible hydrogel lights up the field of soft hydrogel interfaces suitable for both wearable and implantable applications. Given that, we proposed a strategy of combining chemical cross-linking and stimuli-responsive physical interactions to construct a biocompatible multifunctional hydrogel. In this hydrogel system, ureidopyrimidinone/tyramine (Upy/Tyr) difunctionalization of gelatin provides abundant dynamic physical interactions and stable covalent cross-linking; meanwhile, Tyr-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) acts as a conductive filler to establish electrical percolation networks through enzymatic chemical cross-linking. Thus, the hydrogel is characterized with improved conductivity, conformal biointegration features (i.e., high stretchability, rapid self-healing, and excellent tissue adhesion), and multistimuli-responsive conductivity (i.e., temperature and urea). On the basis of these excellent performances, the prepared multifunctional hydrogel enables multimodal wearable sensing integration that can simultaneously track both physicochemical and electrophysiological attributes (i.e., motion, temperature, and urea), providing a more comprehensive monitoring of human health than current wearable monitors. In addition, the electroactive hydrogel here can serve as a bidirectional neural interface for both neural recording and therapeutic electrostimulation, bringing more opportunities for nonsurgical diagnosis and treatment of diseases.

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

“…As such, there is a significant interest in developing advanced optoelectronic devices that may enable future human-centric applications (Figure ). These devices may be integrated into a contact lens to diagnose various diseases such as glaucoma and diabetes − or provide augmented/virtual reality vision. − Flexible and stretchable PDs with high resolution can realize various curvy-shaped retinas in natural eyes, which can be implemented in artificial vision for mobile robotics or visual prostheses to provide/restore vision. − Fully mimicked, bioinspired artificial imagers can provide user-friendly preprocessed images, minimizing the computational cost for refining the raw data. − Wearable and implantable devices can be used to detect activities in the brain, heart, and muscles, blood pressure, and other vital signs. − The collected data can be transmitted to the cloud for real-time analysis to assist in predictive diagnostics or provide proper treatment, including but not limited to drug delivery and therapy based on thermal, electrical, and ultrasound stimulation. − These soft sensors and actuators can also be applied to various prosthetics or human-machine interfaces (HMIs) to restore senses or major functionalities of the human body. − In conjunction with the artificial intelligence (AI) technology, the human-centric devices with flexible and stretchable form factors are expected to bring a change of paradigm in medicine from treatment to diagnosis, prevention, and restoration, transitioning to personalized precision medicine. Through the utilization of medical big data, AI can impact various areas of healthcare, including prediction, diagnosis, treatment, and rehabilitation.…”

Flexible Self-Powered Photoelectrochemical Photodetectors Based on Cellulose-Based Hydrogel Electrolytes and Bi2O2Se Nanosheets

“…Hydrogels, which consist of three-dimensional networks with a large quantity of water or ionic liquids, have attracted extensive interest as soft materials for flexible stretchable electronics owing to their advantages, such as superior flexibility, conformality to complex surfaces, self-healing ability, and tunable electrical properties. − These features enable them to have several potential applications in various fields, such as electronic skins, smart wearable devices, flexible pressure/strain sensors, and robots . Natural polymers are one of the most promising bioresources for replacing nondegradable polymers.…”

Co-functional Group Conducting Hydrogels Inspired by Ligament for Flexible Electronic Devices

“…14 Moreover, most chemical bonds in chemical cross-linking points are nondynamic and difficult to re-bond after destruction which make hydrogels show a poor self-healing ability. 15 As presented by Sun and co-workers, 16 a hydrogel-integrated multimodal response sensor based on chemical cross-linking of gelatin, ureidopyrimidinone/tyramine (Upy/Tyr), and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) is fabricated for a flexible supercapacitor. Due to the high conductivity of the hydrogel, the multimodal response sensor shows good electrochemical performance.…”