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A strategy of coupling bionics is adopted on a paper-based sensor to achieve these excellent functions simultaneously, including multivariable detection, ultrasensitivity, waterproof and underwater applications.

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.

Recently, there has been tremendous interest in flexible pressure sensors to meet the technological demands of modern society. For practical applications, pressure sensors with high sensitivity at small strains and low detection limits are highly desired. In this paper, inspired by the slit sensillum of the scorpion, a flexible pressure sensor is presented which has regular microcrack arrays and its reversed pattern acts as a tunable contact area of the sensing material microstructures. The template with regular crack arrays generated on the inner surface is fabricated using a solvent-induced swelling method, which provides a simple and economical way to obtain the controllable fabrication of crack arrays without any physical damage to materials. At the same time, the working principle of the bio-inspired pressure sensor is attributed to pressure-dependent variations because of the contact area change between the interlocking polydimethylsiloxane films with the negative and positive patterns of the microcrack arrays. The device shows good performance, with a gauge factor of 27.79 kPa−1 (0–2.4 kPa), a short response/recovery time (111/95 ms), a low detectable pressure limit and excellent reproducibility over 3000 cycles. Practical applications, such as the detection of human motion and touch sensing, are then tested in this work, and the results imply that it should have significant potential applications in numerous fields. Note that the reversed pattern of the slit sensillum of the scorpion is explored to enhance the performance of pressure sensors, thus opening a new route for the fabrication of flexible pressure sensors, even wearable electronics, in a cost-effective and scalable manner.

In this work, inspired by some typical creatures from nature with superhydrophobic surfaces, a bio-inspired antifogging PDMS is designed and fabricated successfully using UV lithography and a template method. First, we fabricated an SU-8 layer with a bio-inspired micro-pillared array (MPA) using traditional UV lithography. Then, it was used as a template to fabricate a PDMS film (PF). After that, it was chemically modified with SiO2 coatings. It was found that the PF coupled with sprayed SiO2 coatings and a MPA have a higher water contact angle (CA) of 158° and a lower contact angle hysteresis (CAH) of less than 2°. Water drops can be separated from this bio-inspired PDMS surface within 86.8 ms. More importantly, this film’s antifogging property is superior, with a recovery time of less than 13 s, which is significantly superior to that of the flat PF and the PF with the MPA. Afterwards, FTIR was applied to analyse the surface chemistry features and suggested that the bio-inspired PF has extremely low surface tension. So, it can be confirmed that an excellent superhydrophobic antifogging property has been achieved on the surface of the PF. Meanwhile, the microscopic and macroscopic dynamic movement behaviour of the fog drops was further observed. Then, the underlying antifogging mechanism was also revealed. These properties mainly benefit from the coupling effect of intermolecular attraction of droplets, chemical compositions (nanometre roughness SiO2) and the physical structures (MPA). The investigations offer a promising way to handily design and fabricate multiscale hierarchical structures on polymers and other materials. More importantly, these findings suggest great potential value for specific antifogging applications in display devices, transport, agricultural greenhouses, food packaging and solar products, especially in continuous harsh fogging conditions.

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.

Recently, the electrosurgical electrode used in minimally invasive surgery is becoming more and more popular as it causes only a little trauma and slight pain, and has other advantages. However, its high working temperature, above 400 °C, often results in serious tissue adhesion on the surface of the electrode, which seriously affects the normal operation of the surgery. In this paper, we develop a novel type of electrode with a coupled bionic anti-adhesive surface by fabricating microstructures inspired by the maize leaf and coating a thin layer of TiO2 film on it. The grid-like microstructures inspired by the maize leaf were fabricated by laser marking technology. Then, the sol–gel method was chosen to prepare the TiO2 coating. The surface characterization of the electrode substrate, bionic electrode and coupled bionic electrode was carried out after fabrication. Afterwards, the wettability and components of these were measured and analysed, respectively. Furthermore, in order to determine the adhesion behaviour of different electrodes, electric cutting experiments were performed on fresh isolated animal liver tissue in detail. Finally, the relationships between adhesion mass, cutting time and cutting depth were also measured. The results show that the coupled bionic electrode surface has the most effective anti-adhesion performance compared with the bare original electrode surface under a high temperature. The investigations carried out in this work offer a promising way to design and fabricate anti-adhesive surfaces working at higher temperatures.

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.

Inspired by cicada wings that can greatly minimize the reflectivity on their surfaces over broad angles or frequency ranges due to the presence of tapered pillar arrays, we fabricated a polydimethylsiloxane (PDMS) positive replica of cicada wings, which demonstrated antireflective and super-hydrophobic characters. Firstly, the cicada wings were selected as a template to duplicate a SiO2 negative replica. Then, the SiO2 negative replica was used as a secondary template to prepare a PDMS positive replica. The resultant PDMS replica inherited the nano-conical structures and thus exhibited outstanding antireflective effect. A suppression of reflectance to a minimum of 0.7% that benefits from nano-cones has been achieved, since the path length and quantity of the incident light irradiated onto PDMS could be increased by incorporating anti-reflective and light scattering patterns. In the meantime, the PDMS replica demonstrates super-hydrophobicity due to the presence of nano-cone structures. The PDMS replica of cicada wings that possesses both anti-reflective and superhydrophobic properties may hold great promise for applications in anti-reflection and self-cleaning windows, in photovoltaic cells, telescopes, camera lenses, glass windows and beyond.

When the sunlight irradiates the surface of butterfly wings, it can be absorbed by the microstructures in the wings scales and converted into heat to maintain the butterfly’s metabolism. This phenomenon is an inspiration which is facilitating the scientific research in solar energy utilization. In this study, the absorption characteristics of seven species of butterfly were investigated using a spectrometer. It was found that the butterfly Heliophorus ila Lvcaenidae showed more efficient absorption capability (absorptivity was about at 85%) compared with other species in the wavelength range from 230 nm to 850 nm. Then, the morphology and structures of the butterfly Heliophorus ila Lvcaenidae wing scales were examined by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The results showed that there were two kinds of scales distributed on the wing surface of the butterfly Heliophorus ila Lvcaenidae. Finally, the optical mechanisms were revealed by theories of multiple reflection and resonance. It was confirmed that the hierarchical hollow nano-architectures of the scales were responsible for the high-efficiency absorption behaviour. This study could be used as a theoretical reference for subsequent bionic design of structural materials for solar energy utilization.

Butterflies are famous for their brilliant iridescent colors, which arise from the unparalleled photonic nanostructures of the scales on their wings. In this paper, the sensitivity characteristics of the photonic structures in butterfly wings to surrounding media were found. First, it was shown that the iridescent scales of Morpho menelaus butterfly give a different optical response to surrounding vapours of water, ether and ethanol. Then, the ultra-depth three-dimensional microscope and FESEM were used to observe the morphology and nanostructures of butterfly wing scales. The high spectral response characteristics were identified by using an Ocean Optics spectrometer USB4000. It was found that the reflectance spectra of the Morpho menelaus butterfly scales could provide information about the nature of the surrounding vapours. Afterwards, the theory of multilayer-thin-film interference was used to analyse the mechanism of this sensitivity. It was determined that the multilayer-thin-film interference structure constituted by alternating films with high and low refractive indexes, leading to the sensitivity of butterfly wings. The refractive indexes of surrounding media play an important role in gas sensitivity. These characteristics dramatically outperform those of existing nano-engineered photonic sensors and may have potential in the design of efficient and high sensitivity optical gas sensors.