Highly Sensitive and Bendable Capacitive Pressure Sensor and Its Application to 1 V Operation Pressure-Sensitive Transistor

Abstract

Development of highly sensitive pressure sensors that function well even in bending environments and operate at ultralow voltage is desirable for wearable applications. Here, a highly sensitive and bendable capacitive pressure sensor with the ability to distinguish pressure and bending stimuli and a pressure-sensitive transistor (PST) that can be easily integrated into wearable sensor system due to ultralow voltage (as low as 1 V for stable signal detection) operation is demonstrated. By introducing surface treatment and bonding technique, all components of the pressure sensor are tightly bonded to each other, enabling high bending stability. The sensor shows high pressure sensitivity (9.9 kPa(-1)) and can detect pressure even in the bending state. Additional bending sensors enables to separately detect signals from the actual pressure and bending deformation. In order to implement low-power sensor circuitry, the PST is fabricated by integrating the pressure sensor and inkjet-printing single-walled carbon nanotube thin film transistor. Such low-voltage operation of the PST enables to demonstrate the stand-alone wearable user-interactive pulse monitoring system by using commercially available electronic devices. The strategy for bendable low-power sensor may enable realization of wearable sensing system and electronic skins with low power consumption in near future.