A micro-/nanoscale hierarchical rough structure inspired by the underwater superaerophobicity of fish scales was fabricated by ablation of a silicon surface by a femtosecond laser. The resultant silicon surface showed superhydrophilicity in air and became superaerophobic after immersion in water. Additionally, inspired by the underwater superaerophilicity of lotus leaves, we showed that the polydimethylsiloxane surface after femtosecond laser ablation exhibits superhydrophobicity in air and becomes superaerophilic in water. The underwater superaerophobic surface showed excellent antibubble ability, whereas the underwater superaerophilic surface could absorb and capture air bubbles in a water medium. The experimental results revealed that the in-air superhydrophilic surface generally shows superaerophobicity in water and that the in-air superhydrophobic surface generally shows underwater superaerophilicity. An underwater superaerophobic porous aluminum sheet with through microholes was prepared, and this sheet was able to intercept underwater bubbles and further remove bubbles from water. In contrast, the underwater superaerophilic porous polytetrafluoroethylene sheet could allow the bubbles to pass through the sheet. We believe that these results are highly significant for providing guidance to researchers and engineers for obtaining excellent control of bubbles' behavior on a solid surface in a water medium.

A fast and single-step process is developed for the fabrication of low-cost, high-quality, and large-area concave microlens arrays (MLAs) by the high-speed line-scanning of femtosecond laser pulses. Each concave microlens can be generated by a single laser pulse, and over 2.78 million microlenses were fabricated on a 2 × 2 cm(2) polydimethylsiloxane (PDMS) sheet within 50 min, which greatly enhances the processing efficiency compared to the classical laser direct writing method. The mechanical pressure induced by the expansion of the laser-induced plasmas as well as a long resolidifing time is the reason for the formation of smooth concave spherical microstructures. We show that uniform microlenses with different diameters and depths can be controlled by adjusting the power of laser pulses. Their high-quality optical performance is also demonstrated in this work.

A bioinspired method to realize transparent underwater superoleophobic and anti-oil surfaces by a femtosecond laser treatment.

This paper presents a one-step method to fabricate superhydrophobic surfaces with extremely controllable adhesion based on PDMS microwell arrays. The microwell array structures are rapidly produced on PDMS films by a point-by-point femtosecond laser scanning process. The as-prepared superhydrophobic surfaces show water controllable adhesion that ranges from ultrahigh to ultralow by adjusting the extent of overlap of the adjacent microwells, on which the sliding angle can be controlled from 180° (a water droplet can not slide down even when the as-prepared surface is turned upside down) to 3°. A "micro-airbag effect" is introduced to explain the adhesion transition phenomenon of the microwell array structures. This work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controllable adhesion.

A simple and efficient technique for large-area manufacturing of concave microlens arrays (MLAs) on silica glasses with femtosecond (fs)-laser-enhanced chemical wet etching is demonstrated. By means of fs laser in situ irradiations followed by the hydrofluoric acid etching process, large area close-packed rectangular and hexagonal concave MLAs with diameters less than a hundred of micrometers are fabricated within a few hours. The fabricated MLAs exhibit excellent surface quality and uniformity. In contrast to the classic thermal reflow process, the presented technique is a maskless process and allows the flexible control of the size, shape and the packing pattern of the MLAs by adjusting the parameters such as the pulse energy, the number of shots and etching time.