Turning Trash Into Treasure: Egg‐Shell Waste Embedded Gelatin Composite Biodegradable Films for Triboelectric Tactile Sensing and Information Encoding

With the advent of flexible electronics, electronic skins (e-skins) have also progressed heavily in terms of acquiring multi-functionality, like flexibility, conformability, biodegradability, and energy autonomy. However, combining all these functions into a single e-skin device is a significant challenge, mainly because the majority of e-skins are composed of plastic, which results in electronic waste (e-waste). To meet these challenges, this work develops flexible single-electrode triboelectric nanogenerators (S-TENGs) using waste egg-shell incorporated gelatin composite as the active layer. Egg-shells, conventionally a domestic bio-waste, augment the output performance to twice that of gelatin-based S-TENGs. Furthermore, such devices exhibit a peak output power density of around 34 W/m² when subjected to hand-tapping pressure with approximately 200 kPa (∼4 Hz). They also exhibit superior pressure sensitivity of 3.48 V/kPa and a fast response time of ∼0.4 ms. Such energy harvesting capability allows the e-skins to demonstrate precise tactile sensing and spatial pressure mapping with no external power supply. These devices also possess promising applications in information encoding through Morse code transmission. Notably, the fabricated devices are highly biodegradable in both phosphate-buffered saline (PBS) solutions and soil. Hence, these multi-functional characteristics and applications enable the developed e-skins to effectively transform bio-waste into useful treasures.