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Flexible strain sensors have an irreplaceable role in critical and emerging fields, such as electronic skins, flexible robots, and prosthetics. Although numerous efforts have been made to improve sensor sensitivity to meet specific application scenarios, the signal-to-noise ratio (SNR) is an extremely critical and non-negligible indicator, which takes into account higher sensitivity, meaning that they can also detect the noise signals with high sensitivity. Coincidentally, scorpions with ultrasensitive vibration sensilla also face such a dilemma. Here, it is found that the scorpion ingeniously uses the viscoelastic material in front of its slit sensilla to realize efficient preprocessing of the signal. Its mechanism is that the loss factor of materials changes with frequency, affecting energy storage and transmission. Inspired by this ingenious strategy, a bioinspired strain sensor insensitive to a low strain rate was designed using a two-step template transfer method. As a result, its relative change in resistance reached 110% under the same strain (0.3197%) but with different strain rates (0.1 Hz and ∼20 Hz). The noncontact vibration experiments also show different responses to low-frequency vibration and high-frequency impact. Moreover, it can also be used as a typical flexible strain sensor. Under the tensile state, it has a gauge factor (GF) as high as 4596 upon 0.6% strain, and the response time is 140 ms. Therefore, it is expected that this strain sensor will be used in many important ultraprecision measurement fields, especially when the measured signal is small.

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.

Ultra-sensitive cantilever transducers are always considered as a platform for the next generation of physical, chemical, and biological sensors. However, it is still a significant challenge to design artificial ultra-sensitive cantilever transducers, especially with a simple structure using a simple method and materials. A scorpion can sense extremely small air flow using only the simple cantilever-like trichobothria on its pedipalp. It can transduce micro airflow signals into deflection without bending. It was shown that the trichobothria in scorpion are mainly made up of two parts: the low-aspect-ratio elastic tissue and the high-aspect-ratio rigid hair shaft. More importantly, the aspect ratio and stiffness of the rigid hair shaft are extremely larger than those of the elastic tissue. Due to these special material and structural characteristics, the cantilever can achieve a high aspect ratio. Inspired by this principle, herein, a kind of deflection transducer with a high aspect ratio was designed. The results confirm that the designed transducer can also catch the stimulus signals by deflection, which can better concentrate stress. Moreover, this kind of transducer has higher sensitivity, easy fabrication, and low cost. Therefore, it is expected that this kind of new bioinspired sensor can be well-applied in many important engineering fields.

There is currently a growing demand for flexible strain sensors with high performance and water repellency for various applications such as human motion monitoring, sweat or humidity detection, and certain underwater tests. Among these strain sensors, paper-based ones have attracted increasing attention because they coincide with the future development trend of environment-friendly electronic products. However, paper-based electronics are easy to fail when they encounter water and are thus unable to be applied to humid or underwater circumstances. Herein, based on a strategy of coupling bionics inspired by lotus leaf and scorpion, which exhibit superhydrophobic characteristics and ultrasensitive vibration-sensing capacity, respectively, a paper-based strain sensor with high sensitivity and water repellency is successfully fabricated. As a result, the strain sensor exhibits a gauge factor of 263.34, a high strain resolution (0.098%), a fast response time (78 ms), excellent stability over 12,000 cycles, and a water contact angle of 164°. Owing to the bioinspired structures and function mechanisms, the paper-based strain sensor is suitable to not only serve as regular wearable electronics to monitor human motions in real-time but also to detect subtle underwater vibrations, demonstrating its great potential for numerous applications like wearable electronics, water environmental protection, and underwater robots.