Bioinspired, Omnidirectional, and Hypersensitive Flexible Strain Sensors

Abstract

Sensors are widely used in various fields, among which flexible strain sensors that can sense minuscule mechanical signals and are easy to adapt to many irregular surfaces are attractive for structure health monitoring, early detection, and failure prevention in humans, machines, or buildings. In practical applications, subtle and abnormal vibrations generated from any direction are highly desired to detect and even orientate their directions initially to eliminate potential hazards. However, it is challenging for flexible strain sensors to achieve hypersensitivity and omnidirectionality simultaneously due to the restrictions of many materials with anisotropic mechanical/electrical properties and some micro/nanostructures they employed. Herein, it is revealed that the vision‐degraded scorpion detects subtle vibrations spatially and omnidirectionally using a slit sensillum with fan‐shaped grooves. A bioinspired flexible strain sensor consisting of curved microgrooves arranged around a central circle is devised, exhibiting an unprecedented gauge factor of over 18 000 and stability over 7000 cycles. It can sense and recognize vibrations of diverse input waveforms at different locations, bouncing behaviors of a free‐falling bead, and human wrist pulses regardless of sensor installation angles. The geometric designs can be translated to other material systems for potential applications including human health monitoring and engineering failure detection.

A multifunctional flexible sensor with coupling bionic microstructures inspired by nature

“…Thus, it is worth learning from nature's creatures to develop sensors with similar or even better performance. Based on our previous work, the slit unit structure was optimized as V-shaped groove; 54,55 herein, the V-shaped groove was also compared with some other grooves with different cross-section shapes by finite element analysis (Fig. S1, ESI †), then the groove was introduced into the design of a resistive-type sensor.…”

Self-reporting of damage in underwater hierarchical ionic skinsviacascade reaction-regulated chemiluminescence

“…The gauge factor (GF) is a parameter used to evaluate the sensitivity of sensors and is defined by the equation GF = (DR/R 0 )/e, where e is the applied strain. 47,48 The GF values of the original and healed HI-skins were calculated to be 0.70 and 0.68, respectively, suggesting complete recovery in sensitivity after healing. The HI-skins exhibited highly repeatable and reversible sensing performance under both small and large tensile strains (Fig.…”

Transparent stretchable hydrogel sensors: materials, design and applications

“…Flexible sensors attract extensive attention due to their portability, 1 mechanical robustness, 2 high flexibility 3 and great conformability, 4 which can transform external stimuli, such as strain, 5,6 pressure, 7,8 temperature, 9,10 and chemical substances, 11,12 into detectable signals (such as resistance, 13 color, 14 voltage, 15 capacitance 16 ). A hydrogel is a kind of 3D cross-linked network composed of hydrophilic polymer chains with an aqueous-rich environment.…”