Tissue-Adaptive Bionogel Based on Piezo-Driven Ion Confinement for Mechanical Biosignal Acquisition System

As advancements in management remain insufficient for chronic patients, death per cardiovascular disease has perpetually increased, becoming a global encumberment today. For the effective approach towards the challenges of healthcare technologies in this field, the use of implantable bioelectronics shows optimistic potential to precisely monitor the mechanical biosignals (blood pressure, respiratory rate) in real-time. However, since conventional bioelectronics commonly use rigid metal and inorganic materials, a mechanical mismatch occurs between the bioelectronics and soft tissues, resulting in low sensitivity and signal-to-noise ratio (SNR). To overcome these concerns, the tissue-level modulus of soft materials (e.g., hydrogel and ionogel) is critical for the development of implantable bioelectronics. Despite the fact that the soft hydrogel can firmly adhere to tissues, the impaired long-term stability caused by dehydration of solvent, and ion exchange between biological ions and synthetic ions leads to erroneous monitoring of biosignals.<br/><br/>In this talk, we propose a novel design of biocompatible ionogel (Bionogel) exploiting a piezo-driven ion confinement structure that prevents ion exchange and enables precise mechanical biosignal readout. To introduce mechanosensitive characteristics to the proposed design of the ion confinement structure, we develop soft Bionogel composed of hydrogen-bonded choline-based ion pairs on the surface of functionalized gold particles (AuNPs) embedded into chitosan biopolymer matrix. Unlike the phenomenon of the ion transfer at the interface between hydrogel and tissues, our Bionogel is capable of minimizing ion exchange by capturing ions. Such confined ion pairs can be dissociated under mechanical stimuli, resulting in reversible ion pumping. Notably, our Bionogel-based mechanotransducer exhibit exhibits exceptional mechanosensitivity (S = 14.60-10.18 kPa^-1) over a wide range of pressures (0 – 100 kPa). Furthermore, cell (Human Dermal Fibroblast) viability and cytotoxicity tests performed on Bionogel signify the enhanced biocompatibility compared to the conventional iongel and conducting polymer. As a result, we believe that the successful integration of the Bionogel-based mechanotransducer into the implantable bioelectronics capable of perceiving subtle signals from the human body can serve as a blueprint for the development of the next-generation health monitoring system.