Self-powered control interface based on Gray code with hybrid triboelectric and photovoltaics energy harvesting for IoT smart home and access control applications

The rapid expansion of Internet of Things (IoT) in many living environments, such as smart home, has motivated the development of human-machine interfaces (HMIs) for the interactions between human and machine. In this paper, a sliding operation triboelectric nanogenerator (TENG) based control disk interface, generating 3-bit binary-reflected Gray-code (BRGC), is developed by integrating copper electrodes, polytetrafluoroethylene (PTFE) film, photovoltaic cell, and electronic signal processing circuits. Eight sensing transitions are successfully achieved by the 3-bit BRGC encoding patterns with two electrodes. One electrode represents the binary bit “0”; another electrode represents the binary bit “1”. A third electrode located in the middle of the disk is utilized to indicate the sliding directions (inward or outward). The output signal detection mechanism and signal processing circuit have been developed, and a Bluetooth transmitter is employed for enabling controlling applications wirelessly. Besides the self-powered sensing characteristic of the triboelectric control disk, a hybrid energy harvester that can harvest triboelectric and photovoltaics energy is proposed to power the entire electronic control circuit. Finally, this triboelectric control disk is employed as a self-powered interface for smart home control and password authentication access control system, which exhibits promising reliability, practicality, and flexibility.