Highly Sensitive Piezoresistive Pressure Sensor Based on Super-Elastic 3D Buckling Carbon Nanofibers for Human Physiological Signals’ Monitoring

Abstract

The three-dimensional (3D) carbon nanostructures/foams are commonly used as active materials for the high-performance flexible piezoresistive sensors due to their superior properties. However, the intrinsic brittleness and poor sensing properties of monolithic carbon material still limits its application. Rational design of the microstructure is an attractive approach to achieve piezoresistive material with superior mechanical and sensing properties, simultaneously. Herein, we introduce novel three-dimensional buckling carbon nanofibers (3D BCNFs) that feature a unique serpentine-buckling microstructure. The obtained 3D BCNFs exhibit superior mechanical properties, including super-elasticity (recovery speed up to 950 mm s−1), excellent flexibility (multiple folds), high compressibility (compressed by 90%), and high fatigue resistance (10,000 bending cycles). The pressure sensor fabricated by the 3D BCNFs shows a high sensitivity of 714.4 kPa−1, a fast response time of 23 ms, and a broad measuring range of 120 kPa. The pressure sensor is further applied to monitor the physiological signals of humans, and is capable of detecting the characteristic pulse waves from the radial artery, fingertip artery, and human-breath, respectively.

Bioinspired Low Hysteresis Flexible Pressure Sensor Using Nanocomposites of Multiwalled Carbon Nanotubes, Silicone Rubber, and Carbon Nanofiber for Human–Computer Interaction

“…52,53 Carbon nanofibers (CNF), known for their excellent electrical and thermal conductivity, high specific modulus, specific strength, and thermal stability, exhibit intrinsic properties of carbon-based nanomaterials while retaining the softness and processability of textile fibers. 54 In the present work, we present a novel approach to developing a flexible pressure sensor by drawing inspiration from the unique characteristics of crocodile skin. Our sensor design features a sandwich-like structure that mimics the hemispherical raised sensory organs on the crocodile's skin.…”

“…Various methods, such as spraying, sputtering, and spinning, have been recommended for coating the conductive material onto the sensor. , However, the key to enhancing sensor sensitivity lies in maximizing its initial resistance in the absence of contact and minimizing resistance upon the application of pressure to amplify the change in the resistance signal. Spray coating with conductive fiber-like nanomaterials offers a viable solution to achieve both benefits and enhance sensor sensitivity. , Carbon nanofibers (CNF), known for their excellent electrical and thermal conductivity, high specific modulus, specific strength, and thermal stability, exhibit intrinsic properties of carbon-based nanomaterials while retaining the softness and processability of textile fibers …”