Abstract
In engineering, cracks are typically regarded as defects due to enormous stress amplification at tip of the crack. Conversely, scorpion ingeniously utilizes the “risky” near-tip stress field of a crack-shaped slit to accurately detect weak vibration signal without causing catastrophic crack propagation from the slit tip. The present paper focuses on the balance strategy between structural safety and sensing accuracy of slit-based mechanical sensilla. We performed a detailed structural and mechanical property study of tissue around the slit wake utilizing a complementary combination of various experimental methods. The results indicate that there is a special thin surface membrane covering the slit wake and the elastic moduli of the membrane and exoskeleton are 0.562 GPa and 5.829 GPa, respectively. In addition, the ratio of bending stiffness between exoskeleton and membrane tissue is about 8 × 104. The theoretical and simulation analysis show that the surface membrane—with appropriate elastic modulus and bending stiffness—can achieve different forms of deformation with the change of slit width for protecting the mechanosensory structure without sacrificing the sensing accuracy. This finding offers a crucial theoretical basis for the further design of bionic mechanical sensors based on the near-tip stress field of artificial cracks.
Highlights
Bionic engineering provides a promising alternative method in expediting the development of artificial systems [1,2,3]
Mechanical signals can only be sensed by organisms after inducing the deformation of specialized mechanosensory structure, which requires that the excellent sensing ability must be based on the outstanding resistance to catastrophic fatigue failure of sensory materials [16,17,18]
The results indicate that, on the one hand, the surface membrane covering the slit wake can absorb strain
Summary
Bionic engineering provides a promising alternative method in expediting the development of artificial systems [1,2,3]. The corresponding mechanical sensilla, composed of mechanosensory microstructure, special materials and sensory neurons, have provided broad biologically inspired strategies for designing mechanical sensors with high performance [11,12,13,14,15]. Research on the excellent sensing mechanism of the slit unit indicates that to maximize the sensitivity of BCSS, the scorpion has evolved an ingenious strategy to make a “risky” nanoscale near-tip stress field, and the receptive field of mechanosensory neurons overlap at a crack-shaped slit tip [9]. The crack-shaped slit as a sensory structure should generate sufficiently large stress amplification for excellent perceptive function but will have superior crack resistance for avoiding catastrophic fractures from the slit tip. This work provides a crucial biomimetic design strategy for the further development of mechanical sensors utilizing the near-tip stress field
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