Stretchable and Printable Medical Dry Electrode Arrays on Textile for Electrophysiological Monitoring

Abstract

Medical electrodes are medical devices that facilitate the transfer energy of ionic currents in the body into electrical currents that can be amplified, studied, and used for diagnosis of medical condition of the patients. Multi-channel and wearable electrode arrays are even more challenging for the medical dry electrodes to simply and accurately achieve electrophysiological signals such as electromyography (EMG). There are a few challenges in materials preparation and device fabrication have to be solved: i) highly conductive and highly conformal electrode materials in order to reduce the contact impedance with human skin; ii) facile patterning and integration procedures of large area multi-channel electrodes with high throughput and low costs; iii) good adhesion between electrodes and substrate materials to avoid delamination after multiple use. Herein, we demonstrate a simple and low-cost fabrication process of stretchable and printable medical dry electrode arrays based on highly conductive composites to simultaneously resolve all the above challenges. The proposed electrode arrays (2 rows × 8 columns = 16 channels) are screen printed on thermoplastic polyurethanes (TPU) film substrate and bonded with textile by hot melt adhesive. The electrodes are composed of flexible conductive composites of TPU/Ag formed by mixing silver micro-flakes with TPU/DMF solution and followed by heat curing at 80 °C for 2 h. The TPU/Ag conductive composite is intrinsic stretchable with high electrical conductivity up to 2.76 × 106 S m-1 at 85 wt% silver loading. The as-prepared multi-channel electrode arrays are easily attached onto human body such as arm, leg and forehead, etc, and they demonstrate excellent performance in accurately detecting forearm EMG signals for various motions.