摘要
With the rapid development of the Internet of Things(IoTs),wearable sensors are playing an increasingly important role in daily monitoring of personal health and wellness.The signal-to-noise-ratio has become the most critical performance factor to consider.To enhance it,on the one hand,good sensing materials/devices have been employed;on the other hand,signal amplification and noise reduction circuits have been used.However,most of these devices and circuits work in an active sampling mode,requiring frequent data acquisition and hence,entailing high-power consumption.In this scenario,a flexible and wearable event-triggered sensor with embedded signal amplification without an external power supply is of great interest.Here,we report a flexible two-terminal piezotronic n-p-n bipolar junction transistor(PBJT)that acts as an autonomous and highly sensitive,current-and/or voltage-mediated pressure sensor.The PBJT is formed by two back-to-back piezotronic diodes which are defined as emitter-base and collectorbase diodes.Upon force exertion on the emitter side,as a result of the piezoelectric effect,the emitter-base diode is forward biased while the collector-base diode is reverse biased.Due to the inherent BJT amplification effect,the PBJT achieves record-high sensitivities of 139.7 kPa^(-1)(current-based)and 88.66 kPa^(-1)(voltage-based)in sensing mode.The PBJT also has a fast response time of<110 ms under exertion of dynamic stimuli ranging from a flying butterfly to a gentle finger touch.Therefore,the PBJT advances the state of the art not only in terms of sensitivity but also in regard to being self-driven and autonomous,making it promising for pressure sensing and other IoT applications.
基金
funded by the National Key R&D Program of China(2019YFA0706100)
National Natural Science Foundation of China(61974006)
the Guangdong Introducing Innovative and Enterpreneurial Teams Program(2019ZT08Z656)
the Shenzhen Municipal Scientific Program(KJZD20230923113759002).
