为实现基于超快激光铝板浸润性梯度轨迹上的液滴无泵运输,进一步提高液滴运动速度,利用纳秒激光器在1050铝板上制备出超疏水表面,再通过飞秒激光器在超疏水表面制备出楔形超亲水轨迹。采用接触角测量仪、电子扫描显微镜和傅里叶红外光谱仪测量样品表面的浸润性、表面形貌和化学成分,通过高速摄像机记录液滴在水平面和30°斜面上的运动情况。结果表明:通过激光方法可在铝板上制备出浸润性循环转变的表面,接触角由0°变为164.6°,再由164.6°变为0°;随着超亲水轨迹楔角α由4°变为10°,液滴的最大速度由300 mm/s变为500 mm/s;随着样品的加热环境由空气变为真空,样品滚动角由大于30°降为3.04°,液滴的平均速度由50 mm/s变为100 mm/s。增大轨迹楔角或降低超疏水表面黏附力,都可以有效提高液滴在浸润性梯度轨迹上的运动速度。

This study aims to achieve pump-free transport of droplets along an infiltrating gradient trajectory on an aluminum plate by using ultrafast lasers and further increase the speed of the droplet movement. First, a superhydrophobic surface is prepared on a 1050 aluminum plate by using a nanosecond laser. Then, a wedge-shaped superhydrophilic trajectory is prepared on this superhydrophobic surface by using a femtosecond laser. The wettability, surface topography, and chemical composition of the sample surface are measured by using a contact angle measuring instrument, an electron scanning microscope, and a Fourier infrared spectrometer, respectively. The movement of droplets on the horizontal plane and the plane with a slope of 30° is recorded by using a high-speed camera. Results show that a surface with wettability-recycling property could be prepared on an aluminum plate by using a laser method. The contact angle could change from 0° to 164.6° and then from 164.6° to 0°. The hyper hydrophilic trajectory wedge angle changes from 4° to 10°, whereas the maximum droplet velocity changes from 300 to 500 mm/s. The sample heating environment changes from air to vacuum, sample rolling angle reduces from above 30° to 3.04°, and average droplet velocity changes from 50 to 100 mm/s. Therefore, it can be concluded that increasing the trajectory wedge angle or reducing the adhesion of the superhydrophobic surface can effectively improve the movement speed of droplets along the wettability gradient trajectory.