Hierarchically Microstructure-Bioinspired Flexible Piezoresistive Bioelectronics

Abstract

The naturally microstructure-bioinspired piezoresistive sensor for human–machine interaction and human health monitoring represents an attractive opportunity for wearable bioelectronics. However, due to the trade-off between sensitivity and linear detection range, obtaining piezoresistive sensors with both a wide pressure monitoring range and a high sensitivity is still a great challenge. Herein, we design a hierarchically microstructure-bioinspired flexible piezoresistive sensor consisting of a hierarchical polyaniline/polyvinylidene fluoride nanofiber (HPPNF) film sandwiched between two interlocking electrodes with microdome structure. Ascribed to the substantially enlarged 3D deformation rates, these bioelectronics exhibit an ultrahigh sensitivity of 53 kPa–1, a pressure detection range from 58.4 to 960 Pa, a fast response time of 38 ms, and excellent cycle stability over 50 000 cycles. Furthermore, this conformally skin-adhered sensor successfully demonstrates the monitoring of human physiological signals and movement states, such as wrist pulse, throat activity, spinal posture, and gait recognition. Evidently, this hierarchically microstructure-bioinspired and amplified sensitivity piezoresistive sensor provides a promising strategy for the rapid development of next-generation wearable bioelectronics.

Morphological Engineering of Sensing Materials for Flexible Pressure Sensors and Artificial Intelligence Applications

“…Microengineering has been used to fabricate capacitive, resistive, piezoelectric, and triboelectric pressure sensors with very high sensitivities, very low detection limits, large working ranges, high transparency, and selective sensing. These high-performing sensors meet the emerging requirements of pressure sensors and have been used in exciting demonstrations, including wearable electronics in health care [ 1 , 2 , 31 , 34 , 39 , 103 , 266 ], intelligent devices for smart homes [ 16 , 50 , 72 , 205 ], digitizing sport [ 21 , 51 , 52 , 267 ], wireless monitoring in security [ 17 , 23 , 53 ], and ML-enabled intelligent sensor [ 54 – 60 ].…”

“…16 h) [ 35 ]. Wearable sensors are convenient for monitoring and correcting the sitting posture by attaching the sensor to the person’s back [ 39 ] and detecting movement signals of the human body (fingers, wrists, arms, knees, and other joint movements) to prevent accidental injuries (Fig. 16 i) [ 36 ].…”

“…A detailed analysis of the engineered microstructure materials with unique sensing performances and their fabrication techniques are compared. In addition, important applications in the areas of healthcare [ 2 , 31 , 39 ], smart homes [ 49 , 50 ], digitizing sports [ 20 , 21 , 51 ], wireless monitoring in security [ 17 , 23 , 53 ], ML-enabled intelligent sensing platforms [ 54 – 60 ] have been discussed.…”

“…Due to rapidly advancing techniques in electrical sensing, material sciences, system engineering, and signal processing, flexible pressure sensors have been investigated in multiple disciplines because of their unique advantageous properties, such as outstanding flexibility, low cost, and compatibility with large-area processing techniques [ 25 – 29 ]. For example, flexible pressure sensors can be attached to the human body for real-time monitoring of different physiological parameters like blood pressure [ 2 , 30 ], blood flow [ 1 , 30 ], pulse beat [ 2 , 6 , 31 , 32 ], heartbeat [ 32 ], respiration [ 31 , 32 ], tremor [ 33 – 35 ], and body movement [ 36 – 39 ]. These parameters are of vital importance in biomedical research, disease diagnosis, and timely treatment.…”

Full-Textile Human Motion Detection Systems Integrated by Facile Weaving with Hierarchical Core–Shell Piezoresistive Yarns

“…The wearable intelligent system has attracted increasing research interest due to its capabilities of facile interaction with and continuous monitoring of the human body. It has shown great potential in various fields such as personalized health care, electronic skins, human–machine interfaces, humanoid robots, and so forth. − As a necessary perception component, flexible pressure sensors with simple manufacturing steps, efficient integration, and high sensing performances are required in the wearable intelligent system. − Piezoresistive sensors show great advantages over other types of pressure sensors, including a simple working mechanism, easy processing, and relatively low power consumption. − Until now, extensive efforts have been devoted to improving the sensing performances, ranging from designing microstructures to choosing advanced functional and substrate materials. − For flexible piezoresistive pressure sensors, reversible deformation of the contact area or sites arises under pressure, which in turn induces electrical resistance changes. − Although piezoresistive pressure sensors based on film materials and template transfer methods have made significant progress, their unsatisfying breathability and comfortability for prolonged wearing prohibit their extensive application. The inherent characteristics of textile materials, such as comfort, outstanding breathability, cost-effectiveness, brilliant three-dimensional (3D) conformability, and hierarchical microstructures, , make them an attractive candidate for constructing flexible piezoresistive pressure sensors.…”