Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC, 3001, Australia.
School of Engineering, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia.
Sci Rep. 2017 Jul 27;7(1):6652. doi: 10.1038/s41598-017-07025-x.
The Miniaturised Lab-on-a-Disc (miniLOAD) platform, which utilises surface acoustic waves (SAWs) to drive the rotation of thin millimeter-scale discs on which microchannels can be fabricated and hence microfluidic operations can be performed, offers the possibility of miniaturising its larger counterpart, the Lab-on-a-CD, for true portability in point-of-care applications. A significant limitation of the original miniLOAD concept, however, is that it does not allow for flexible control over the disc rotation direction and speed without manual adjustment of the disc's position, or the use of multiple devices to alter the SAW frequency. In this work, we demonstrate the possibility of achieving such control with the use of tapered interdigitated transducers to confine a SAW beam such that the localised acoustic streaming it generates imparts a force, through hydrodynamic shear, at a specific location on the disc. Varying the torque that arises as a consequence by altering the input frequency to the transducers then allows the rotational velocity and direction of the disc to be controlled with ease. We derive a simple predictive model to illustrate the principle by which this occurs, which we find agrees well with the experimental measurements.
采用表面声波（SAWs）驱动毫米级薄片旋转的微型盘上实验室（miniLOAD）平台，可以实现其更大尺寸的实验室光盘（Lab-on-a-CD）的小型化，从而实现真正的便携化，用于即时护理应用。然而，原始的 miniLOAD 概念的一个显著限制是，它不能在不手动调整盘的位置或使用多个设备来改变 SAW 频率的情况下，灵活地控制盘的旋转方向和速度。在这项工作中，我们展示了使用锥形叉指换能器来限制 SAW 束的可能性，从而使它产生的局部声流通过流体动力剪切在盘上的特定位置施加力。通过改变换能器的输入频率来改变产生的扭矩，从而可以轻松地控制盘的旋转速度和方向。我们推导出一个简单的预测模型来说明发生这种情况的原理，我们发现该模型与实验测量结果非常吻合。
