Drawn‐on‐Skin Sensors from Fully Biocompatible Inks toward High‐Quality Electrophysiology

Abstract

The need to develop wearable devices for personal health monitoring, diagnostics, and therapy has inspired the production of innovative on‐demand, customizable technologies. Several of these technologies enable printing of raw electronic materials directly onto biological organs and tissues. However, few of them have been thoroughly investigated for biocompatibility of the raw materials on the cellular, tissue, and organ levels or with different cell types. In addition, highly accurate multiday in vivo monitoring using such on‐demand, in situ fabricated devices has yet to be done. Presented herein is the first fully biocompatible, on‐skin fabricated electronics for multiple cell types and tissues that can capture electrophysiological signals with high fidelity. While also demonstrating improved mechanical and electrical properties, the drawn‐on‐skin ink retains its properties under various writing conditions, which minimizes the variation in electrical performance. Furthermore, the drawn‐on‐skin ink shows excellent biocompatibility with cardiomyocytes, neurons, mice skin tissue, and human skin. The high signal‐to‐noise ratios of the electrophysiological signals recorded with the DoS sensor over multiple days demonstrate its potential for personalized, long‐term, and accurate electrophysiological health monitoring.

Skin bioelectronics towards long-term, continuous health monitoring

“…A general way to quantitively evaluate biocompatibility is cell viability assay, 207,208 which is in vitro, i.e., a cellular-level biocompatibility. An in vivo approach is to attach samples onto animal tissues or human skin and investigate the presence of inflammation, 209 fibrotic reaction, 23 or irritations. 21 3.1.4.…”

“…The sensor was not dislodged or malfunctioning during the 3 days, demonstrating the robustness of this sensor for long-term monitoring. 209 Separating the device from skin by packaging it in a silicone shell (e.g., Ecoflex) is another strategy to achieve long-term stability. 31,[258][259][260][261] Stable continuous monitoring can be achieved as long as the liquid does not leak or evaporate out of the packaging over time, or its performance decreases over time.…”

“…, a cellular-level biocompatibility. An in vivo approach is to attach samples onto animal tissues or human skin and investigate the presence of inflammation, 209 fibrotic reaction, 23 or irritations. 21…”

“…The sensor was not dislodged or malfunctioning during the 3 days, demonstrating the robustness of this sensor for long-term monitoring. 209…”

Motion Artifact‐Resilient Zone for Implantable Sensors

“…[9,13,14] As an example, a tactile sensor aims to recognize touch. [10,15,16] However, dynamic movement is also a factor that generates signal change without touch, and it results in the user recognizing a virtual touch that does not really exist. The canceling of dynamic noises and extraction of the target signal represent essential issues in body-interfaced devices.…”