Advances in Soft and Dry Electrodes for Wearable Health Monitoring Devices

• Authors: Hyeonseok Kim, Georgia Institute of Technology; Eugene Kim, Georgia Institute of Technology; Chanyeong Choi, Georgia Institute of Technology; Woon-Hong Yeo, Emory University
• Journal Title: MICROMACHINES
• Volume: Volume 13, Number 4
• Publisher: MDPI | 2022-04-01
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.3390/mi13040629
• Subjects: Engineering, Mechanical
• Keywords: Science & Technology; Physical Sciences; Technology; Chemistry, Analytical; Nanoscience & Nanotechnology; Instruments & Instrumentation; Physics, Applied; Chemistry; Science & Technology - Other Topics; Physics; soft-dry electrode; wearable device; health monitoring; physiology signal sensing; manufacturing; ON-SKIN ELECTRONICS; FLEXIBLE ELECTRODES; BIOCOMPATIBILITY; GRAPHENE; MOTION; NANOMATERIALS; FABRICATION; IMPEDANCE; SENSORS; NOISE

Abstract

Electrophysiology signals are crucial health status indicators as they are related to all human activities. Current demands for mobile healthcare have driven considerable interest in developing skin-mounted electrodes for health monitoring. Silver-Silver chloride-based (Ag-/AgCl) wet electrodes, commonly used in conventional clinical practice, provide excellent signal quality, but cannot monitor long-term signals due to gel evaporation and skin irritation. Therefore, the focus has shifted to developing dry electrodes that can operate without gels and extra adhesives. Compared to conventional wet electrodes, dry ones offer various advantages in terms of ease of use, long-term stability, and biocompatibility. This review outlines a systematic summary of the latest research on high-performance soft and dry electrodes. In addition, we summarize recent developments in soft materials, biocompatible materials, manufacturing methods, strategies to promote physical adhe-sion, methods for higher breathability, and their applications in wearable biomedical devices. Fi-nally, we discuss the developmental challenges and advantages of various dry electrodes, while suggesting research directions for future studies.