Towards seamless conformable and comfortable wearable electronics: Polyimide-supported dry electrodes integrated in knitted fabrics

Abstract

Wearable electronics contribute directly to advancing numerous biomedical devices in contract with the human body. These electronic devices have been transformed from rigid and bulky into soft and flexible. Conformable electronics is actively pursued in the literature to comply with the curvilinear surface of the skin. To increase the adoption rate, seamless comfortable operation is necessary, which requires more focus on convenient materials such as textiles, compared to elastomer-based technologies. This study demonstrates mechanically reliable stretchable interconnects embedded within textile to achieve both conformability and comfort. Electromyography (EMG) signals provide invaluable information about body motion analysis, muscle nerve and fatigue disorders. Non-invasive surface EMG is the preferred method of measurement since it can be conducted with minimal risk to the subject. In this study, polyimide-supported dry electrodes are integrated in knitted fabrics using a special knit pattern to ensure achieving higher contact surface area with the human skin. The received EMG signals are benchmarked against standard wet electrodes in time and frequency domain, revealing comparable performance. The presented technology exhibits extremely high mechanical reliability, withstanding up to 10,000 cyclic elongations at 60 % strain. The integration strategy is sufficiently strong and durable, retaining its electrical properties after 20 standard washing cycles. The findings indicate that the presented technology holds significant promise towards real-world implementation of seamless, conformable, and comfortable wearable electronics.