The mode conversion of acoustic surface waves contacted by liquid droplets has been utilized for the propulsion of nanoliter droplets with respect to lab-on-a-chip applications. In this case, however, piezoelectric substrates equipped with interdigital transducers on the surface on which the droplets are moving have been used for the excitation of surface acoustic waves. Our approach is aiming at the acceleration of comparatively large droplets such as raindrops on non-piezoelectric substrates, e. g. glass plates. Following this approach, we have excited Lamb waves on glass plates by piezoelectric interdigital transducers attached at the rear side of the substrate, which are not in contact with the liquid. A propulsive action on water droplets of ÃÂÿl size has been observed, which could be improved by hydrophobic surface coatings. With continuous wave excitation at a frequency of 1 MHz and an amplitude of 200 Vpp an acceleration of about 1 m/s2 has been achieved so far with water droplets of 10 ÃÂÿl on a 1 mm thick glass plate. This concept allows numerous technical applications, including two-dimensional droplet relocation or ÃÂÿintelligentÃÂÿ droplet removal from glass panels in combination with droplet detection via a Lamb wave transmission line established by a second interdigital transducer.
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机译:相对于芯片实验室应用,已经利用液滴接触的声表面波的模式转换来推动纳升液滴。然而,在这种情况下,在液滴正在移动的表面上配备有叉指式换能器的压电基板已经用于激发表面声波。我们的方法旨在加速较大的液滴,例如非压电基板上的雨滴。 G。玻璃板。按照这种方法,我们通过附着在基板背面且不与液体接触的压电叉指式换能器激发了玻璃板上的兰姆波。已经观察到对ƒ大小的水滴的推进作用,可以通过疏水性表面涂层改善这种作用。到目前为止,在频率为1 MHz且振幅为200 V pp sub>的连续波激励下,当水滴为10时,加速度约为1 m / s 2 sup>在1毫米厚的玻璃板上。此概念允许大量技术应用,包括二维液滴重定位或玻璃面板中的液滴去除,以及通过第二秒建立的Lamb波传输线进行液滴检测的结合叉指换能器。
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