Nanomaterial-Enhanced Biopolymer-Based TENGs as Sustainable Energy Harvesters for Wearables and On-Skin Electronics

Presently, on-skin wearable devices rely heavily on non-rechargeable batteries, which are not only harmful to the environment but also raise concerns about toxicity. As a result, there is a pressing need to develop self-powered energy sources that are environmentally friendly and compatible with human use. Triboelectric nanogenerators (TENGs) offer a promising solution as sustainable and biofriendly candidates for green energy generation. These TENG devices effectively convert mechanical energy from everyday activities, such as biomechanical motions, into electrical energy. They boast cost-effectiveness, easy fabrication, and high efficiency, making them ideal for self-powered electronics and independent power sources. However, a major drawback is that many TENGs still rely on non-eco-friendly fluorinated polymers, which can cause discomfort and skin infections when used in on-skin wearables. To overcome these challenges, our study introduces a novel approach, enhancing the performance of TENGs through a cellulose-based tribopositive layer integrated with nanomaterials. These nanomaterials include surface functional groups introduced via nano-coating or chemical/mechanical reduction to form nanocrystals or fibers. Moreover, we explore the potential of a new bio-polymer-based tribonegative layer, mimicking the chemical structure of conventional non-biodegradable materials, and incorporating nanomaterials for improved efficiency. In the pursuit for a completely biodegradable TENG, we replace the substrate with a biopolymer film and implement carbon-based electrodes, both integrated with nanomaterials. The resulting bio-TENGs exhibit remarkable flexibility, biocompatibility, and breathability, rendering them ideal for wearable devices capable of harvesting energy from biomechanical motions. Notably, these devices display outstanding performance, generating output voltage values surpassing 1 kV, attributed to the synergistic effects of nanomaterials in the triboelectric layers. This represents a twofold increase compared to conventional substrates and electrode materials that utilize polyimide as a negative triboelectric layer. Furthermore, our all-biopolymers-based TENGs surpass 500V in output voltage, outperforming other reported bio-TENG devices in voltage generation. The integration of nanomaterials components in these bio-TENGs opens up new possibilities for sustainable wearable electronics, ushering in a greener and more environmentally friendly era of energy generation and utilization