Conventional acoustofluidics are restricted to manipulation of droplets on a flat surface, and there is an increasing demand for acoustofluidic devices to be performed at inclined surfaces to facilitate multilayered microfluidic device design and enhance system compactness. This paper reports theoretical and experimental studies of acoustofluidic behaviors (including transportation/pumping and jetting) along inclined surfaces using AlN/Si Rayleigh surface acoustic waves (SAWs). It has been demonstrated that for droplets with volume smaller than 3 μL, they could be efficiently transported on arbitrary inclined surfaces. The gravity effect would play a more and more important role in uphill climbing with the increased inclination angle. When the inclination angle was increased up to 90°, a higher threshold power was needed to transport the droplet and the maximum droplet volume which can be pumped also reached its minimum value. Effects of surface inclination angle on droplet jetting angles could be neglected for their volumes less than 2 μL. Moreover, microfluidic and acoustic heating performances of AlN/Si SAWs were further studied and compared with those conventional ZnO/Si SAWs with the same electrode configurations.

常规的声流体技术仅限于在平坦表面上对液滴的操作，并且对在倾斜表面上进行声流体设备的需求日益增长，以促进多层微流体设备的设计并提高系统的紧凑性。本文报道了使用AlN / Si Rayleigh表面声波（SAWs）沿倾斜表面的声流体行为（包括运输/泵送和喷射）的理论和实验研究。已经证明，对于体积小于3μL的液滴，它们可以有效地在任意倾斜表面上传输。随着倾斜角度的增加，重力效应将在上坡攀爬中发挥越来越重要的作用。当倾斜角度增加到90°时，需要更高的阈值功率来运输液滴，可以泵送的最大液滴体积也达到了最小值。当其体积小于2μL时，可以忽略表面倾斜角对液滴喷射角的影响。此外，还对AlN / Si SAW的微流体和声加热性能进行了研究，并将其与具有相同电极结构的常规ZnO / Si SAW进行了比较。