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A bionic tactile device is designed for object surface texture recognition, taking inspiration from the microstructure of human fingerprints. The sense of touch in humans is achieved through the frictional vibration and generation of electrical potential signals by subcutaneous receptors. Constructing a tactile sensing device involves generating distinct signals upon interacting with different materials. The piezoelectric film PVDF is particularly suitable as a sensitive material for sensors due to its excellent flexibility, strong mechanical strength, excellent dynamic response and cost-effectiveness. This paper presents the design of a PVDF-based fingerprint-inspired tactile sensor capable of differentiating various textures. By combining the collected signals with machine learning algorithms, diverse textures can be effectively identified. To demonstrate the sensor's superior performance, two experiments were conducted—one focused on recognizing different material textures, and the other on recognizing Braille characters. The accuracy achieved in these experiments was 97.4% and 96.5%, respectively, highlighting the technology's significant potential in intelligent robotics and human-computer interaction. [Display omitted] • A bionic tactile sensor with three different layers were proposed. • Two types of texture datasets were representatively constructed for analytical study. • Some eigenvalue parameters combined with machine learning algorithms was used to achieve high recognition accuracy. [ABSTRACT FROM AUTHOR]

Among various surface modification technologies, laser surface texturing (LST) to introduce texture has attracted more scholars' attention for controlling the tribological performance. The enhanced processing quality of the textured surface results in reducing the coefficient of friction and improving the wear resistance. In this study, dielectric transformer oil was used to protect the surface of GCr15 bearing steel from undesired gases in the atmosphere during the laser processing. Three types of dimples, including circle, rectangle and hexagon, were ablated to evaluate their influence on friction and wear. It was found that LST with transformer oil greatly improved the surface texture processing quality, where the edges of dimples were effectively designed and burrs-free. Results showed that the depth of dimples was reduced up to 7%. Compared to the samples fabricated in air, the friction coefficient and the wear of improved surface were reduced up to 55% and 73.8%, respectively. This was attributed to the excellent shielding and coolant property of transformer oil. Additionally, the shapes of the dimples, the applied force and the sliding speed significantly affected the friction coefficient, where dimples operate as lubricant and debris stores. This study provides certain feasibility guidance for the tribological modification of GCr15 bearing material with oil method and expands its application on engineering surfaces. • Transformer oil-coated LST was introduced to improve the tribological properties. • Circular, rectangular and hexagonal dimples were studied. • LST with oil greatly improved the surface texture processing quality. • The friction and wear were reduced up to 55% and 73.8%, respectively. [ABSTRACT FROM AUTHOR]

Ship hulls and subsea equipment are plagued by current resistance, seawater particles impact, corrosion and other challenges in the ocean. Consequently, developing sustainable nontoxic antifouling coatings is highly urgent. Discoveries from nature have inspired us to design high-efficiency, environmentally friendly, and cost-effective antifouling coatings. In the study, a strategy of combining microstructures and Benzotriazole (BTA) was proposed through constructing shark skin shield scale structure, which improved drag reduction and increased abrasion resistance as well. On the synergistic effect of BTA as corrosion inhibitor, the friction coefficient of the coating was significantly reduced and the anti-corrosion performance was greatly improved. Compared to the smooth pure epoxy coating, the anti-corrosion performance and the drag reduction rate of Texture-BTA-3 % coating was improved by 30 % and about 10 %, respectively. Furthermore, the effect of coating structure on corrosion resistance was revealed. This investigation will broaden the applications in marine navigation with the favorable performance. [Display omitted] • A method for preparing epoxy resin with imitating sharkskin surface texture has been proposed. • Verified the influence of the coating texture on anti-corrosion performance. • Drag reduction rate of the designed coating in water is about 10 %. • The friction coefficient is reduced of 40 % during friction process. [ABSTRACT FROM AUTHOR]

Due to their bioinert and reliable tribological performance, cobalt chromium molybdenum (CoCrMo) alloys have been widely used for articular joint implant applications. However, friction and wear issues are still the main reasons for the failure of implants. As a result, the improvement of the tribological properties and biocompatibility of these alloys is still needed. Thus, surface modification is of great interest for implant manufacturers and for clinical applications. In this study, a strategy combining laser surface texturing and chitosan grafting (mussel inspired) was used to improve the tribological and biocompatible behaviors of CoCrMo. The microstructure and chemical composition were investigated by atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. The tribological properties were discussed to determine their synergistic effects. To evaluate their biocompatibility, osteoblast cells were cocultured with the modified surface. The results show that there is a distinct synergistic effect between laser surface texturing and polymer brushes for improving tribological behaviors and biocompatibility. The prepared chitosan brushes on a textured surface are a strong mechanism for reducing friction force. The dimples took part in the hydrodynamic lubrication and acted as the container for replenishing the consumed lubricants. These brushes also promote the formation of a local lubricating film. The wear resistance of the chitosan brushes was immensely improved. Further, the worn process was observed, and the mechanism of destruction was demonstrated. Co-culturing with osteoblast cells showed that the texture and grafting have potential applications in enhancing the differentiation and orientation of osteoblast cells. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS), as a polymer material with excellent mechanical properties and flexibility, is widely used in flexible wearable devices, soft robots and other fields. Commonly, the Mold-flipping is used to produce PDMS based samples, while it is time-consuming and impractical for the large-scale fabrication. With the additive manufacturing, printing pastes can be freely configured thanks to direct ink writing (DIW) technology, enabling rapid and high precision manufacturing. Herein, we have improved the rheology of Sylgard-184 by adding crosslinkers and silica nanoparticles to make it printable. By adjusting the printing path, flexible surfaces with textures were created. Ball-on-disc dry friction experiments were carried out on the specimens. Results show that the texture produced by the print path can effectively reduce the coefficient of friction (COF) compared to samples produced by the conventional molding. When the print path is at 60° to the sliding direction, COFs for samples are reduced by 23.2% to 32.9%. Our findings provide a new strategy for preparing flexible and wearable devices through significantly enhancing the wear resistance of substantiable usage and prolonging the lifespan. • A method for preparing Polydimethylsiloxane (PDMS) that can be used for direct ink writing has been proposed. • Flexible surfaces prepared at different printing angles have a reduced coefficient of friction compared to cast surfaces. • The coefficient of friction can be reduced by up to 32.9% when printing at an angle of 60°. [ABSTRACT FROM AUTHOR]