Research On Bionic Flexible Strain Sensors Based On The Ultra Sensitive And Highly Reliable Perception Mechanism Of Scorpions

Everything is interconnected,and sensing comes first.As the"eye"of new industrialized intelligent equipment,sensor is the key to develop high-end manufacturing industry,which embodies the state of precision/ultra-precision processing.Among them,the flexible sensor benefits from the extensive ductility and high compliance of the flexible substrate material,which makes up for the defect that the rigid silicon-based sensor substrates in monitoring complex spatial curves or soft objects.Hailed as the new sensory engine in the age of artificial intelligence,they are accelerating developments in human-computer interaction,medical engineering,aerospace,and other fields.However,the journey is not without its challenges.Despite their adaptability,flexible sensors’sensitivity and reliability issues hinder their engineering applications.This problem mainly comes from the attribute defects of the flexible sensor material itself:(1)Isotropic characteristics of the materials limit the sensors to unidirectional strain detection,hampering their ability to ultra-sensitively detect and differentiate strains from various directions;(2)Mechanical hysteresis in these materials causes signal drift during strain,undermining their ability to reliably respond to sustained loads;(3)Their low melting points preclude the use of standard high-temperature welding for reliable connections and integration.Current research focuses on alleviating these issues by developing new sensing materials,but progress is slow,struggling to meet the urgent demand for ultra-sensitive and highly reliable flexible sensors.Many great inventions shaping human civilization have stemmed from biomimetic technologies,where biomimetic thinking fosters new methodologies and ideas,becoming a contemporary research focal point.To address the low sensitivity and reliability shortcomings of flexible sensors,we turn to biomimetics,seeking inspiration from nature.The scorpion,with an evolutionary history of 430 million years,possesses slit sensillum with discrete morphological features that can detect nanoscale vibrational strains at the ends of their metatarsals,enabling an ultra-sensitive perception of external vibrational signals.Furthermore,these receptors use a rigid-flexible coupling material structure to prevent stress damage and crack propagation,ensuring high-reliability sensing under continuous and significant impact strains.The scorpion’s extraordinary sensing capabilities for vibration signals far exceed those of current sensor devices.Its discrete structural features and rigid-flexible material architecture offer fresh perspectives and insights for designing and developing new biomimetic flexible strain sensors.This paper selects the Androctonus australis and Heterometrus petersii as the subjects of biomimetic research.The strategy of"structure design as the main focus,material support structure"is adopted to design and prepare flexible sensors,aiming to improve their sensitivity and reliability.Through theoretical analysis and experimental characterization,the ultra-sensitive sensing mechanism of the scorpion’s discrete structure and the high-reliability sensing mechanism of the rigid-flexible coupled material are revealed.Based on this,three major categories of flexible biomimetic strain sensors—discrete,semi-discrete,and continuous types—are designed and prepared,and a flexible integration method for multi-type sensors is developed.Inspired by the ultra-sensitive and highly reliable sensing mechanisms of the discrete structure of the scorpion’s slit sensillum and the rigid-flexible coupled material,this paper progressively conducts biomimetic design and preparation of sensors from point to line,from discrete to continuous,and tests the advantages of different types of biomimetic flexible strain sensors.The research content is as follows:(1)The study elucidates the ultrasensitive perception mechanism of the discrete structure in scorpion slit sense organs and the highly reliable perception mechanism of hard-soft coupled materials.Correspondingly,it establishes functional bionic mapping models from receptors to sensors:"the Ultrasensitive perception model of discretized energy storage structures"and"the Highly reliable perception model of hard-soft coupled materials".(2)Based on the highly efficient energy conversion mechanism described in the above-mentioned"the Ultrasensitive perception model of discretized energy storage structures",a discrete bionic flexible strain sensor was designed and fabricated.This sensor overcomes the isotropic signal response limitations inherent to flexible sensing materials,achieving anisotropic response sensing for different strain states(magnitude,direction,and speed)through a bionic discrete energy storage structure.Fundamental sensing performance:a local strain interval sensitivity coefficient of approximately 3×10~5 and reliable fatigue resistance over more than 15,000 cycles.(3)Based on the stretching-bridge stabilization mechanism in the aforementioned"the Ultrasensitive perception model of discretized energy storage structures",a semi-discrete bionic flexible strain sensor was designed and fabricated.This sensor addresses the issue of signal response distortion caused by the viscoelastic hysteresis effect of flexible sensing materials.Utilizing the bionic semi-discrete bridging structure,the sensor achieves ultra-sensitive perception of continuous strain signals and high-fidelity signal output with low drift.Fundamental sensing performance:a local strain interval sensitivity coefficient of～19716,and signal low-drift reliability that is two orders of magnitude higher than that of non-bionic structured sensors.(4)Based on the aforementioned"the Highly reliable perception model of hard-soft coupled materials",a continuous bionic flexible strain sensor was designed and fabricated.This addresses the processing challenges associated with low-melting-point flexible sensing materials,enabling rapid flexible welding of the sensor module at room temperature.The sensor exhibits customized ultra-sensitive strain sensing and high-reliability mechanical connections.Fundamental sensing performance:a localized strain sensitivity coefficient of approximately1500 and an ultimate tensile reliability of the flexible sensing material after welding of about1100%.(5)Utilizing biomimetic rigid-flexible coupled materials as an integrated substrate,an efficient vertical integration process for multiple types of flexible sensors was invented,eliminating the need for additional adhesives.Basic processing performance:interlayer integration time<100 s;integration tensile reliability>1000%.