Ultra-sensitive flexible piezoresistive pressure sensor for biopressure and tiny force measurements based on tilted micropillar array microstructures

Abstract Flexible pressure sensor can acquire important information during contact with the human body and the external environment, thus shining in various fields such as rehabilitative monitoring, artificial intelligence and touch-on displays. With the development of the fifth generation (5G) mobile communication technology and the Internet of Things, flexible sensing deivces need to be used more in ultra-precision fields, such as biopressure and tiny force detection, which require devices to have higher sensitivity. In this work, an ultra-sensitive flexible piezoresistive pressure sensor is created by embedding multi-walled carbon nanotubes (MWCNTs) onto a polydimethylsiloxane layer with tilted micropillar array microstructures on its surface. Based on the sensing mechanism of microstructure bending deformation rather than compression deformation, the fabricated device exhibits fascinating properties in terms of ultrahigh sensitivity (1.74 kPa-1), fast response time (< 100 ms), low detection limit (5.8 Pa) and excellent cyclic stability. Furthermore, the prepared sensors can meet the sensing needs in a variety of dynamic environments, including real-time artery pulse, airflow, acoustic vibrations, and finger bending, indicating that the sensing devices have enormous potential in human health assessment and diagnosis, and robotic tactile perception. This work provides an innovative approach for the development of highly sensitive sensors required in practical applications.