Biomimetic sensor technology is always superior to existing human technologies. The scorpion, especially the forest scorpion, has a unique ability to detect subtle vibrations, which is attributed to the microcrack-shaped slit sensillum on its legs. Here, the biological sensing mechanism of the typical scorpion (Heterometrus petersii) was intensively studied in order to newly design and significantly improve the flexible strain sensors. Benefiting from the easy-crack property of polystyrene (PS) and using the solvent-induced swelling as well as double template transferring method, regular and controllable microcrack arrays were successfully fabricated on top of polydimethylsiloxane (PDMS). Using this method, any physical damage to PDMS could be effectively avoided. More fortunately, this bio-inspired crack arrays fabricated in this work also had a radial-like pattern similar to the slit sensillum of the scorpion, which was another unexpected imitation. The gauge factor (GF) of the sensor was conservatively evaluated at 5888.89 upon 2% strain and the response time was 297 ms. Afterward, it was demonstrated that the bio-inspired regular microcrack arrays could also significantly enhance the performance of traditional strain sensors, especially in terms of the sensitivity and response time. The practical applications, such as the detection of human motions and surface folding, were also tested in this work, with the results showing significant potential applications in numerous fields. This work changes the traditional waste cracks on some damaged products into valuable things for ultrasensitive mechanical sensors. Moreover, with this manufacturing technique, we could easily realize the simple, low cost and large-scale fabrication of advanced bioinpired sensors.

Functional electronics has promising applications, including highly advanced human-interactive devices and healthcare monitoring. Here, we present a unique printable micron-scale cracked strain sensor (PMSCSS), which is bioinspired by a spider's crack-shaped lyriform slit organ. The PMSCSS is fabricated by a facile process that utilizes screen-printing to coat carbon black (CB) ink onto a paper substrate. With a certain bending radius, a cracked morphology emerged on the solidified ink layer. The working principle of the PMSCSS is prominently attributed to the strain-dependent variation in resistance due to the reconnection–disconnection of the crack fracture surfaces. The device shows appealing performances, with superfast response times (∼0.625 ms) and high sensitivity (gauge factor = 647). The response time surpasses most recent reports, and the sensitivity is comparable. We demonstrate the application of the PMSCSSs as encoders, which have good linearity and negligible hysteresis. Also, the sensor can be manipulated as a vibration detector by monitoring human-motion disturbances. According to the sensory information, some details of movements can be deduced.

A novel pH-responsive smart device has been developed for continuous separation of oil/water mixtures. Smart surfaces are obtained by electroless silver deposition followed by surface modification with a mixed solution of thiol containing carboxylic groups and methyl groups (HS(CH₂)₁₁CH₃ and HS(CH₂)₁₀COOH). It was found that the wettability of the as-prepared copper foams can switch reversibly between superhydrophobicity and hydrophilicity according to their pH response. The as-prepared copper foam can easily remove the organic solvents either on water or underwater. Furthermore, the as-prepared copper foams can be applied to separate an oil-and-water mixture bidirectionally with high efficiency. This study provides a simple and environmentally friendly route to fabricate oil–water separation materials which have potential applications in industrial fields, such as in water treatment and petroleum refining. In particular, this smart surface is switchable under various pH conditions.