Crack-Across-Pore Enabled High-Performance Flexible Pressure Sensors for Deep Neural Network Enhanced Sensing and Human Action Recognition

Abstract

Flexible pressure sensors with high sensitivity over a broad pressure range are highly desired, yet challenging to build to meet the requirements of practical applications in daily activities and more significant in some extreme environments. This work demonstrates a thin, lightweight, and high-performance pressure sensor based on flexible porous phenyl-silicone/functionalized carbon nanotube (PS/FCNT) film. The formed crack-across-pore endows the pressure sensor with high sensitivity of 19.77 kPa–1 and 1.6 kPa–1 in the linear range of 0–33 kPa and 0.2–2 MPa, respectively, as well as ultralow detection limit (∼1.3 Pa). Furthermore, the resulting pressure sensor possesses a low fatigue over 4000 loading/unloading cycles even under a high pressure of 2 MPa and excellent durability (>6000 cycles) after heating at high temperature (200 °C), attributed to the strong chemical bonding between PS and FCNT, excellent mechanical stability, and high temperature resistance of PS/FCNT film. These superior properties set a foundation for applying the single sensor device in detecting diverse stimuli from the very low to high pressure range, including weak airflow, sway, vibrations, biophysical signal monitoring, and even car pressure. Besides, a deep neural network based on transformer (TRM) has been engaged for human action recognition with an overall classification rate of 94.96% on six human actions, offering high accuracy in real-time practical scenarios.

Wearable Pressure Sensor Array with Layer-by-Layer Assembled MXene Nanosheets/Ag Nanoflowers for Motion Monitoring and Human–Machine Interfaces

“…At present, flexible pressure sensors are mainly divided into resistive, capacitive, , piezoelectric, and self-powered , sensors. The selection of high-quality active materials and expansion of the contact area are the most important ways to obtain high-sensitivity pressure sensors. , On the one hand, two-dimensional (2D) materials have shown good performance advantages in the field of pressure sensors .…”

Crack engineering boosts the performance of flexible sensors

“…The opening microcracks on the surface of electrodes further increased the contact area and enhanced the sensitivity (Figure 9D). The integration of microcracks and pores enabled the preparation of pressure sensors based on a crack‐across‐pore composite structure 105 . When applying a small pressure (0–33 kPa), a concentrated stress distribution occurred around the pores and incited a swift variation of the contact area between cracks near the pores, achieving a sensitivity up to 19.77 kPa –1 .…”

Nonpatterned Soft Piezoresistive Films with Filamentous Conduction Paths for Mimicking Multiple-Resolution Receptors of Human Skin

“…Electronic skin (E-skin), which is electronics that mimic the properties of human skin, has recently received increasing attention owing to its promising applications, such as human–machine interfaces and health monitoring devices. − For E-skin to interact with its surroundings in the same way as real human skin does, it is necessary to develop “skin-like” soft sensors detecting external stimuli, such as pressure, temperature, and humidity. Their intrinsic softness allows them to conform to complex three-dimensional (3D) geometries, which is highly beneficial for high-fidelity detection through conformal interfaces − and high durability under mechanical stress. − Among various types of stimuli, pressure is significantly involved in the majority of the physical contact and physiological activities of the human body. − In this regard, soft pressure sensors that can cover the entire pressure range in our daily life play the most important role in E-skin. Furthermore, with the development of artificial intelligence (AI), it is important to collect various types of spatial inputs with high fidelity, ranging from macroscopic touch to microscale stimuli distribution. − …”