Research On Sensing Mechanism And Bionics Of The Functional Structure Of Micro-vibrational Sensilla Of Scorpion

Sensor is an important tool to obtain external information.It has attracted great attention in the fields of electronic skin,human-computer interaction and medical health.Among many sensors,flexible mechanical sensor is one of the main research directions.Its working principle is to transform the collected physical signals such as strain or pressure from the external environment into quantifiable,identifiable and stored electrical signals,such as voltage,current,etc.At present,the problem faced by the flexible mechanical sensor is that when there is low-frequency noise interference and the useful signal is extremely weak,the useful signal cannot be decoupled.Therefore,finding innovative methods to design and manufacture can not only reduce the interference of low-frequency noise,but also identify the key weak signal is the difficulty and challenge to further improve the signal-to-noise ratio of the sensor.Nature is the best teacher of human beings.After hundreds of millions of years of evolution,in order to adapt to the harsh natural environment and ensure the continuous growth of the population,organisms in nature have evolved a variety of biological receptors with anti-interference,low power consumption and high sensitivity.The raw materials used in biosensors are only several common natural materials,and these materials are synthesized in the natural environment.Unlike humans,it is not necessary to synthesize various new materials in complex and multiple physical fields to prepare sensors.Organisms rely on simple components and common environmental conditions,but they can form receptors that accurately perceive biological related signals in complex environments.Its special mechanism is not clear.Therefore,tapping the potential mechanism of biosensors will provide innovative ideas and natural templates for the design of flexible mechanical quantity sensors.Among the various organisms with mechanical receptors,the arthropod scorpion composed of a series of body segments is a typical representative.Relying on the microvibration receptors on the body surface,it can accurately perceive the vibration signals required by organisms in a complex environment full of vibration signals of various frequencies.For example,the disturbance of underground insects 50 cm from the surface.Therefore,the micro-vibration receptor on the scorpion's body surface must integrate the characteristics of anti-interference,high signal-to-noise ratio and high sensitivity.The deeper research on the micro-vibration receptor will provide inspiration for the design of the corresponding mechanical sensor.In this paper,the adult heteroremtrus petersii was selected as the biological prototype.In situ tracing technique of neurons was used to characterize the position distribution of slit receptor neurons in a single slit receptor.Through the design and construction of a single slit receptor electrophysiological test device,it is found that the slit receptor neurons mainly produce nerve impulses during the extrusion process,but have no obvious response to the relaxation process of the slit unit.It is further revealed that the slit receptor realizes the perception of vibration signals through the extrusion deformation of the slit unit.By studying the potential response of a single slit sensing unit at different frequencies,this paper analyzes the relationship between the lowest amplitude of obvious impulse caused by applying to the end of tarsal bone and the vibration frequency.It is found that the slit receptor is more inclined to receive some high-frequency vibration signals,which is a "high pass filter" on organisms.The transmission path of scorpion slit receptor receiving vibration signal is studied.It is found that there is a special functional structure close to the front end of the slit receptor,which is different from other parts.The key attributes such as its macro shape,structural characteristics,and material properties are analyzed.It is determined that its macro shape is a horseshoe structure,and the structure is a material with low stiffness from the surface to the inside,It has spontaneous fluorescence characteristics similar to that of the flexible slit receptor epidermal membrane.Through the self-made AFM colloidal probe,the reverse reduction of the process of the scorpion foot tarsal squeezing the metatarsal bone in vitro was carried out,and the mechanical properties of the horseshoe structure were analyzed.It was found that the scorpion cleverly used the non-neural viscoelastic material to filter the low-frequency vibration signal,revealing the internal mechanism of the "high pass filtering" characteristics of the scorpion micro-vibration receptor.Further,by revealing the sensing mechanism under the joint action of scorpion slit receptor and horseshoe structure,a bionic design model of resistive strain sensing element inspired by viscoelastic material is established.Based on this model,the corresponding strain sensing element is designed,manufactured,and tested.By testing and applying strains of the same size and different frequencies,it is found that the manufactured sensing element reproduces the sensing function of the slit sensor and the front horseshoe structure,and has a certain attenuation of low-frequency strain signals,so as to achieve the effect of filtering.In addition,it also explores the performance of wearable components in the fields of human-computer interaction and speech recognition.Although the viscoelastic material can make the scorpion slit receptor have the function of attenuation and filtering of low-frequency noise signals,it can also attenuate biological related high-frequency signals.Through micro CT technology,it is found that there are regularly distributed through-hole structures on both sides of scorpion slit receptors,and their morphological characteristics are statistically analyzed.Through the combination of digital image and finite element simulation,it is revealed that the existence of the functional structure of hole will make the deformation of the sensing unit greater,so as to amplify the attenuated signal.The design of the pressure sensor based on the mechanism of ultra-high sensitivity and ultra-low sensitivity to the pressure signal of the porous structure,which further realizes the ultra-low sensitivity to the pressure signal of the hand.To sum up,taking scorpion,a typical representative with anti-interference,high signal-to-noise ratio and high sensitivity,as the biological prototype,this paper reveals that the scorpion micro-vibration receptor realizes the perception of biological signals under interference conditions by filtering low-frequency noise and amplifying highfrequency signals required by organisms,breaking through the traditional method of noise filtering and amplification using active circuits and algorithms.On this basis,a resistive flexible strain sensing element inspired by viscoelastic materials is designed and manufactured,which realizes the filtering function of selective response to lowfrequency signal attenuation and small high-frequency signal attenuation,so as to reduce the interference of low-frequency noise.In addition,based on the signal amplification function of the porous structure,a hypersensitive flexible pressure sensor with the amplification effect of the porous structure is designed and manufactured to amplify the weak pressure signal,so as to improve the sensing sensitivity.