High-Performance Latex-Compounded Nitrile Rubber for Self-Powered Intelligent Traffic Monitoring with Advanced Signal Conditioning

Abstract

Commercialization of triboelectric nanogenerator (TENG) based self-powered sensors has become increasingly significant in the modern era, particularly within the realm of sustainable energy applications. However, the commercial viability of such self-powered sensors hinges on overcoming specific challenges, including the development of materials that excel in both durability and high charge transfer capabilities, addressing signal conditioning of high-amplitude voltage pulses, and integration with microcontrollers. Although rubber materials exhibit superior durability and are well-suited for high-load applications, their inherently low triboelectric performance limits their use in triboelectric sensors. Herein, highly durable and stretchable latex-compounded acrylonitrile butadiene rubber (NBR) based thin sheets are fabricated via the doctors’ blade technique to realize mechanical energy harvesting and to work as self-powered sensors such as speed sensors and direction sensors. The triboelectric positive material NBR offers good durability coupled with a high charge transfer density of 24 nC/cm² when paired with (indium tin oxide) ITO as a tribonegative material. The nitrile rubber is employed in a symmetric TENG structure to develop a road stud to perform self-powered speed-sensing applications. Integration with microcontrollers has enabled wireless speed monitoring, catering to high-speed applications with efficacy. Further, by leveraging NBR as an active tribopositive material, a highly responsive self-powered direction sensor is developed to detect forward and reverse human motions. Capacitor charging characteristics of TENG are utilized to address the challenges in controlling unregulated triboelectric voltage pulses, ensuring noise-free integration with microcontrollers, for real-time direction sensing. Finally, a triboelectric pedestrian crossing detector (PCD) integrating two triboelectric direction sensors was successfully demonstrated to count the number of passengers waiting to cross the road. Thus, the work appeals to highly demanded energy materials for high-energy impact applications and proposes a technology for conditioning unregulated high triboelectric voltage signals.