Agricultural waste rice husk/poly(vinylidene fluoride) composite: a wearable triboelectric energy harvester for real-time smart IoT applications

The ever-expanding demand for smart, wearable, and self-powered devices raises concerns regarding desirable power supplies. Again, this growing use of smart electronics continuously increases the burden on electronic waste (e-waste). Thus, a suitable power supply composed of environmentally friendly materials and assisted by adequate power density is quite enviable in today’s world. Herein, the designing and fabrication of an agricultural waste rice husk ash (RHA)/poly(vinylidene fluoride) (PVDF)-based flexible triboelectric energy harvesting device are demonstrated. The silica (SiO2)-enriched RHA effectively engineered the microstructure of the bio-compatible PVDF and effectively enhanced the electroactive phase fraction. The proof-of-concept of designing the flexible triboelectric energy harvester (TEH) using RHA/PVDF as a functional layer is studied. The fabricated lightweight, wearable TEH can generate a maximum voltage, current, and power density of 463 V, 30 µAmp, and 1.94 mW.cm−2, respectively, under repetitive finger imparting. This significantly enhanced output performance of the optimized TEH is attributed to the coupling of the piezoelectric effect with the triboelectric phenomenon inside the device under each cycle of operation. Owing to the good dynamic pressure sensitivity, the device is quite capable of sensing and scavenging energy from the fine motions of fingers as well as other body joints. Finally, the device was used to assemble self-powered smart sensors in order to conduct smart home and smart library operations. The smart switches can operate the smart home electronic appliances wirelessly from the interior/exterior of the room of the respective building. In smart library applications, the signal generated from the smart sensors can convey useful information to the librarian or the users regarding occupied and empty positions of a particular book on a bookshelf. With the bio-degradable nature of the filler, easy processing of the device, excellent biomechanical energy harvesting capability, and efficacy towards IoT applications, this sustainable bio-organic device paves the way towards effective, flexible, self-powered electromechanical systems for next-generation smart artificial intelligence (AI) and Internet of Things (IoT) applications.