A Fully Integrated Flexible Electronic System With Highly Sensitive MWCNTs Piezoresistive Array Sensors for Pressure Monitoring

Pressure ulcers are a common and costly health problem in clinical medicine, caused primarily by continuous vertical pressure on local tissues of the body. Recently, flexible devices have been used to alert pressure ulcers by continuously monitoring the pressure applied to the human skin. Although many pressure sensors provide excellent sensing performance, they still rely on uncomfortable, unstretchable systems with rigid electronics. These devices are mounted on the human body, which hinders continuous pressure monitoring. Herein, we propose a fully integrated flexible electronic system (FIFES) with highly sensitive multi-walled carbon nanotubes (MWNTs) piezoresistive array sensors for pressure monitoring, which accurately achieves external pressure signals acquisition and independently performs processing and wireless transmission. We develop a heat seal connecting technology for integrating the piezoresistive array sensors and its flexible processing circuit, which overcomes the compatibility defect of a rigid circuit board and the flexible sensors. Furthermore, the Cu–Ge metal sputtering and transferring technologies are employed to achieve an extensible circuit. The as-fabricated fully integrated electronic system has excellent flexibility, a rapid response time (the response/recovery time is 0.11/0.08 s, respectively), a wide dynamic range (6–50 kPa), and an excellent sensitivity (1.61 kPa ⁻¹ for the range under the pressure of 18 kPa, 0.47 kPa ⁻¹ for the range of 18–50 kPa) attributes to the optimized conical microstructures number. Owing to its excellent performance, the FIFES has extensive applications for pressure monitoring in different human epidermises, such as elbow bending and knee-bending. Also, it has immense potential applications in sleep posture monitoring and pressure ulcer warning.