Department of Electrical Engineering, University of Washington, Seattle, Washington 98195, USA.
Langmuir. 2012 Sep 25;28(38):13765-70. doi: 10.1021/la3024309. Epub 2012 Sep 10.
We introduce the wetting barrier ratchet, a digital microfluidic technology for directed drop transport in an open air environment. Cyclic drop footprint oscillations initiated by orthogonal vibrations as low as 37 μm in amplitude at 82 Hz are rectified into fast (mm/s) and controlled transport along a fabricated ratchet design. The ratchet is made from a simple wettability pattern atop a microscopically flat surface consisting of periodic semi-circular hydrophilic features on a hydrophobic background. The microfluidic ratchet capitalizes on the asymmetric contact angle hysteresis induced by the curved features to drive transport. In comparison to the previously reported texture ratchets, wetting barrier ratchets require 3-fold lower actuation amplitudes for a 10 μL drop, have a simplified fabrication, and can be made optically flat for applications where transparency is paramount.
我们介绍了湿滞棘轮，这是一种数字微流控技术，可在开放环境中定向传输液滴。通过低至 37μm 振幅、82Hz 的正交振动引发的循环液滴足迹振荡被纠正为快速（mm/s）并沿着制造的棘轮设计进行控制传输。棘轮由简单的润湿性图案制成，位于微平表面之上，表面由疏水背景上的周期性半圆形亲水特征组成。微流控棘轮利用由弯曲特征引起的不对称接触角滞后来驱动传输。与之前报道的纹理棘轮相比，湿滞棘轮在 10μL 液滴下需要低 3 倍的致动幅度，具有简化的制造工艺，并且可以制成光学平面，适用于透明度至关重要的应用。
