Breathable, Flexible, Transparent, Hydrophobic, and Biotic Sustainable Electrodes for Heating and Biopotential Signal Measurement Applications

Abstract

Pressure to reduce the global amount of e-waste has increased in recent years. The optimal use of natural resources is a demanding area especially due to the overabundance of the use of resources and challenges with after-life disposal. Herein, an easy method is developed to fabricate an improved version of leaf skeleton-based biodegradable, transparent, flexible, and hydrophobic electrodes. A fractal-like rubber leaf skeleton is used as the substrate, physical vapor deposited Au interlayer to promote adhesion, and uniform deposition of overlayer silver nanowires. The fabricated surfaces present a high level of electrical stability, optical transparency, hydrophobicity, and robust mechanical properties. The prepared electrodes demonstrate a comparable level of optical transmittance to the virgin leaf skeleton. The mechanical sturdiness of the electrodes is verified by 1k bending cycles. To demonstrate the functionality of these hybrid biotic conductive network (HBCN) electrodes, their performance is evaluated as flexible transparent heating elements and as biosignal measurement electrodes. The heater can reach a temperature of 140 °C with only 2.5 V in ≈5 s and Ag nanowire loading of ≈160 μg cm−2. Likewise, electrocardiogram (ECG) and electromyogram (EMG) signals are successfully obtained from the electrodes without using any electrode gel or other electrolytes.