Artificial Hair-Like Sensors Inspired from Nature： A Review

Nature creatures have evolved excellent receptors, such as sensory hairs in arthropods, lateral line system of fishes. Researchers inspired by nature creatures have developed various mechanical sensors. Here, we provide an overview on the development of Artificial Hair-Like （AHL） sensors based on the inspiration of hair flow sensory receptors, especially sensory hairs in arthropods and lateral line systems of fishes. We classify the developed AHL sensors into several categories according to the operating principles they based on, for example, piezoresistive and piezoelectric effects. The current challenges and existing problems in the development of AHL sensors are also present, which were primarily restricted by the exploratory tools of sensing mechanism of creatures and current manufacturing technologies. In future, more efforts are required in order to further improve the performance of AHL sensors. We expect that intelligent multi-functional AHL sensors can be applied not only in applications like navigation of underwater automatic vehicles, underwater search and rescue, tap-water metering, air monitoring and even in medicare, but also potentially be used in space robots to detect complex to- pography.

Crack-based and Hair-like Sensors Inspired from Arthropods:A Review

Over a long period of time,arthropods evolve to have two excellent mechanical sensilla of slit sensilla and trichobothria sensilla,which construct a perfect perception system.The former mainly perceives the change of the in-the-plane force while the latter perceives that of the out-of-plane force.In recent years,these two sensilla have attracted researchers as the models for developing artificial mechanical sensors.This review mainly includes the biomechanics and biomimetic manufacturing techniques as well as their future application value.In order to better understand the advantages of biological strategies,this review describes the morphology,mechanical analysis,and information recognition of slit sensilla and trichobothria sensilla.Then this review highlights the recent development of Crack-based Sensors(CBSs)and Hair-like Sensors(HLSs)based on the analysis of biological mechanism.The manufacturing method and substrate of crack in CBS and those of hair rods in HLS are discussed respectively.Finally,the practical applications and potential value of two sensilla,such as flexible wearable electronic devices,robot sensing system,autopilot sensing and wind tunnel speed detection,are briefly discussed.

Micro/nano-scale Characterization and Fatigue Fracture Resistance of Mechanoreceptor with Crack-shaped Slit Arrays in Scorpion

The nocturnal scorpion Heterometrus petersii uses Basitarsal Compound Slit Sensilla (BCSS) as mechanoreceptor to detect mechanical signal (e.g. substrate vibration, cyclic loads caused by walking) without fatigue failure such as initiation of fatigue crack and further propagation of crack-shaped slit. The outstanding perceptive function has been discovered for over half a century. However, it is not yet clear about the microstructure, material composition and micromechanical property which are all important factors that determine the fatigue fracture resistance of the BCSS. Here, the microscopic characteristics of the BCSS were thoroughly studied. The results dicate that anti-fatigue resilin and stiff chitinous cuticle form multilayered composite as the main body of the BCSS. Meanwhile, the pre-existing slit as mechanosensory structure is covered by cuticular membrane which has different mechanical property with the epicuticle. Theoretical analysis shows that the structure-composition-property synergistic relations of composites confer on the BCSS with extreme fatigue fracture tolerance.

Vibrational Receptor of Scorpion(Heterometrus petersii):The Basitarsal Compound Slit Sensilla

Recently,micro-vibrational perception mechanisms of nocturnal arthropods such as scorpions and spiders are attracting increasingly more attention and research.The relevant micro-vibrational receptors are exquisite,in terms of their comprehensive performance such as sensitivity,stability,high anti-interference,and ultralow-power consumption.In this work,we find the Basitarsal Compound Slit Sensilla (BCSS) of scorpion (Heterometrus petersii) are composed of the crack-shaped slits as mechanosensory structure and can efficiently detect substrate-borne vibrational signal in complex natural environment.The study on microstructures and mechanical properties of tissue phases constituting the BCSS reveals that the strategy of tessellation is used to make crack-shaped slit amplify the tiny mechanical signal.In addition,the magnitude-frequency characteristics of electrophysiological signals caused by vibration stimulation with different frequencies indicate that the scorpion is sensitive to micro-vibrational signals at a certain frequency range.Meanwhile,the vibrational perception mechanism based on geometrical amplification and resonance is proposed to explain how scorpions detect the tiny biotic vibrational signal efficiently in noise environment.This finding not only promotes our further understanding of ultra-sensitive mechanism of the vibrational receptors,but also provides biological inspiration for the next generation of mechanosensor for a broad range of applications.