Flexible Equivalent Strain Sensor with Ordered Concentric Circular Curved Cracks Inspired by Scorpion

Abstract

Slit sensillum, a unique sensing organ on the scorpion’s legs, is composed of several cracks with curved shapes. In fact, it is just its particular morphological distribution and structure that endows the scorpions with ultrasensitive sensing capacity. Here, a scorpion-inspired flexible strain sensor with an ordered concentric circular curved crack array (CCA) was designed and fabricated by using an optimized solvent-induced and template transfer combined method. The morphology of the cracks can be effectively controlled by the heating temperature and the lasting time. Instead of the nonuniform stress distribution induced by disordered cracks, ordered concentric circle curved structures are introduced to generate a uniform stress distribution and larger deformation, which can significantly improve the performance of the strain sensor. Thus, the CCA sensor exhibits ultrahigh sensitivity (GF ∼ 7878.6), excellent stability (over 16 000 cycles), and fast response time (110 ms). Furthermore, the CCA sensor was demonstrated to be feasible for monitoring human motions and detecting noncontact vibration signals, indicating its great potential in human-health monitoring and vibration signal detection applications.

Wearable Plant Sensors Based on Nanometer-Thick Ag Films on Polyethylene Glycol Terephthalate Substrates for Real-Time Monitoring of Plant Growth

“…The result showed no significant drift or change of the relative resistance, which means stability and repeatability, and has the potential for long-term recycling in practical applications. Compared with the 2000 and 5000 cycle lifetimes of sensors based on crack structures in existing reports, the wearable plant sensor designed and prepared in this paper meets the requirements of high cycle stability. In addition, the mechanical robustness of the sensor was tested under stress–strain cycles; the corresponding results are shown in Figure S9.…”

“…In the compressed state, it shows a response time of 300 ms and a recovery time of 400 ms. Compared with 137 ms response time of the flexible sensor based on crack structure and titanium/gold conductive layer material 31 and 169 ms response time of the flexible sensor based on web radiation and spiral structure 34 in the existing reports, the wearable plant sensor designed and prepared in this paper meets the requirements of fast response. The short response time allows the sensor to detect the excitation signal quickly and convert it into the electrical signal output when subjected to rapid external excitation, which plays an important role in practical applications.…”

“…In this study, inspired by the slit sensillum of scorpion, which possesses powerful sensing capability, − we developed a low-cost, large-scale fabrication process for developing wearable plant sensors. Without photolithography, inversion, etching, etc., a 82 μm “scorpion slit” was copied out and then a 120 nm-thick Ag layer was deposited, which exhibited ultrasensitive vibration-sensing capacity and could detect vibrations due to horizontal and vertical growth.…”

Stretchable and Sensitive Strain Sensors Based on CB/MWCNTs–TPU for Human Motion Capture and Health Monitoring

“…Obviously, the sensitivity of the sensor can be improved by reducing the initial resistance of the sensor and enhancing the resistance variation of the sensor. In order to reduce the initial resistance of the sensor, researchers often use metal particles or conductive nanomaterials with good conductivity to construct conductive network on flexible substrates. − Meng et al sprayed silver nanoparticles onto a flexible substrate made of carbon nanotubes (CNTs) and poly­(dimethylsiloxane) (PDMS) to prepare an ultrahigh sensitivity (GF = 7878.6) flexible strain sensor, while the maximum strain is ∼1% . Zhang et al prepared a redox graphene/silk (rGO/silk) flexible strain sensor using electrospinning and vacuum filtration methods, realizing a maximum GF of 436 and a maximum tensile strain of 8.7% .…”

“…16−19 Meng et al sprayed silver nanoparticles onto a flexible substrate made of carbon nanotubes (CNTs) and poly(dimethylsiloxane) (PDMS) to prepare an ultrahigh sensitivity (GF = 7878.6) flexible strain sensor, while the maximum strain is ∼1%. 20 Zhang et al prepared a redox graphene/silk (rGO/silk) flexible strain sensor using electrospinning and vacuum filtration methods, realizing a maximum GF of 436 and a maximum tensile strain of 8.7%. 21 In addition, researchers enhance the resistance change of the sensor by introducing a crack structure and enhancing the stress concentration in the sensor.…”