Pressure sensitivity and wide range are two crucial features of flexible electromechanical sensors for applications in the next‐generation of intelligent electronics, such as wearable healthcare monitors and soft human–machine interfaces. Conventional pressure sensors have a narrow pressure range (<10 kPa) and complex fabrication processes, which significantly hinder their extensive applications. A facile laser‐engraving method is proposed to fabricate a flexible multiwalled‐carbon‐nanotube (MWCNTs)/poly(dimethylsiloxane) (PDMS) composite‐based piezoresistive sensor with hierarchical microstructures. Herein, the nonstandard‐circular feature and Gaussian distributed facula of a laser spot are utilized to produce the middle‐level porous microdome upon the bottom‐level cylinder microcolumn array, while the top‐level tentacle‐like conical micropillars are produced by vertically rotating the acrylic mold during the laser engraving process. This novel hierarchical microstructure endows the proposed piezoresistive sensor with orders‐of‐magnitude of higher sensitivity (≈35.51 kPa⁻¹) than that of other reported electromechanical sensors and a more extensive pressure sensing range up to 23 kPa. Moreover, the detection limit of the sensor is down to 2 Pa, which makes it a desirable candidate for monitoring subtle pressure. The sensor is successfully applied to distinguish the syllables of each pronounced word, detect movements of the human wrist, and monitor radial arterial pulse, thus demonstrating its promising applications in wearable electronics.

Femtosecond laser processing gradient wettability is emerging as a powerful technology to control the wettability of surfaces due to its several advantages such as low pollution, good stability, and short processing cycle. A micro-textured surface with a stripe groove structure was processed on the surface of an AlN ceramic using a 1030 nm femtosecond laser. The surface roughness, the chemical composition, contact angle, and surface microstructures were determined using optical profilometry, X-ray photoelectron spectroscopy, contact angle measuring instrument and, scanning electron microscope, respectively. The wettability surfaces of different gradients were obtained by changing the number of laser scanning passes. Moreover, the flow state of the droplet on the gradient wettability surface was observed via a high-speed camera. The experimental results show that as the surface roughness increases, the surface wettability gradually becomes hydrophilic. Furthermore, the hydrophobic loss is due to the increase in the number of hydrophilic C–O bonds and to the reduction of the hydrophobic C–C bonds on the surfaces. And, the wetting rate of the droplet is faster when a large gradient is present. This new technology can be applied in cutting tools with their rake face subject to reduced wear and to improve the machining efficiency and accuracy.

Chemical modification is usually utilized for preparing superhydrophobic SiC surfaces, which has the problems of long processing time, high environmental contamination risk, and high cost. To enhance the condensation heat transfer efficiency of SiC, the superhydrophobic SiC surface was fabricated through laser texturing and heat treatment. In this study, the SiC surface was processed by laser texturing with a nanosecond laser, followed by heat treatment. Surface microstructures and compositions were investigated with SEM and XPS, and the heat transfer coefficient of the superhydrophobic SiC surface was tested. The results indicated that the laser-textured SiC surface had a super hydrophilic contact angle of 0°; after heat treatment, SiC ceramic became superhydrophobic (surface contact angle reaches 164°) because organic contamination on the original SiC surface could be cleaned by using laser texturing, which caused a chemical reaction and the formation of SiO₂ on the surface. Moreover, the distribution of relatively low-energy SiO_X was formed after heat treatment; then, SiC ceramic became superhydrophobic. Due to the formation of nanoscale sheet-like protrusion structures by heat treatment, the SiC superhydrophobic surface exhibited typical dropwise condensation, and the condensation heat transfer coefficient reached 331.8 W/(m²·K), which was 2.3 times higher than that of the original surface.

Investigating the wettability of the tool surface made of cemented carbide is of great significance to improve its working life and quality. The micropit array was processed on the surface of cemented carbide YT15 by a 1064 nm femtosecond pulse laser. Then, the optical microscope, the optical profilometer, and the contact angle measuring instrument were applied to measure the surface morphology and the surface contact angle of micropits. The influence of different laser parameters on surface morphology and the surface contact angle was studied. The geometric morphology model of the micropit was established. The influence of the morphology of micropits on the surface contact angle is analyzed based on the Wenzel theory. The results show that the radius and depth of micropits have a positive correlation with the average laser power and scanning times. As the spacing increases, the surface roughness factor and the surface contact angle decrease. There is a strong correlation between the characterization parameters kurtosis, skewness, and surface wettability in a 3D height parameter system. The smaller the kurtosis, the greater the skewness and the better the surface hydrophilicity.

The heat transfer performance of Flat micro heat pipe (FMHP) is mainly determined by liquid absorption capacity of the wick. A chemical-free laser selective micro-texture technology is proposed for the fabrication of FMHP. Series of samples with different widths of the superhydrophobic-superhydrophilic spacing stripes were prepared by laser micro texturing, and their transport capacity was tested. Scanning electron microscope, three-dimensional optical profiling, and X-ray photoelectron spectroscope techniques were used to characterize the surfaces, and the mechanism of accelerating liquid reflux was investigated. Two samples with the same spacing width were used to make FMHPs. The heat transfer performance of each group of FMHPs was tested, including the start-up time, steady state temperature, and axial maximum temperature difference, and the corresponding thermal resistances were calculated. The results show that the width of superhydrophobic-superhydrophilic spacing stripes can affect the capillary force and hysteresis force during droplet transport, thereby affecting the droplet transport velocity, and in turn, influencing the heat transfer performance of the FMHP. Compared with most current flat micro heat pipes, the laser selective textured heat pipe with superhydrophobic-superhydrophilic stripes can significantly improve the heat transfer performance, and is promising for heat transfer applications in microelectronic equipment.