Holmes Hal R, Böhringer Karl F
Department of Bioengineering, University of Washington, Seattle, WA 98105, USA.
Department of Electrical & Computer Engineering and Institute for Nano-engineered Systems (NanoES), University of Washington, Seattle, WA 98105, USA.
Micromachines (Basel). 2019 Jan 19;10(1):69. doi: 10.3390/mi10010069.
The droplet response to vibrations has been well characterized on open substrates, but microfluidic applications for droplets on open systems are limited by rapid evaporation rates and prone to environmental contamination. However, the response of enclosed droplets to vibration is less understood. Here, we investigate the effects of a dual-plate enclosure on droplet transport for the anisotropic ratchet conveyor system. This system uses an asymmetric pattern of hydrophilic rungs to transport droplets with an applied vibration. Through this work, we discovered that the addition of a substrate on top of the droplet, held in place with a 3D printed fixture, extends the functional frequency range for droplet transport and normalizes the device performance for droplets of different volumes. Furthermore, we found that the edge movements are anti-phasic between top and bottom substrates, providing a velocity profile that is correlated to vibration frequency, unlike the resonance-dependent profiles observed on open systems. These results expand the capabilities of this system, providing avenues for new applications and innovation, but also new insights for droplet mechanics in response to applied vibration.
液滴对振动的响应在开放基底上已得到充分表征，但开放系统中液滴的微流体应用受到快速蒸发速率的限制，且容易受到环境污染。然而，封闭液滴对振动的响应尚不太清楚。在此，我们研究了双板封装对各向异性棘轮输送系统中液滴传输的影响。该系统利用亲水性梯级的不对称图案，通过施加振动来传输液滴。通过这项工作，我们发现，在液滴上方添加一块由3D打印固定装置固定的基底，可扩展液滴传输的功能频率范围，并使不同体积液滴的设备性能标准化。此外，我们发现顶部和底部基底之间的边缘运动是反相位的，从而提供了一个与振动频率相关的速度分布，这与在开放系统中观察到的依赖共振的分布不同。这些结果扩展了该系统的能力，为新应用和创新提供了途径，也为响应施加振动的液滴力学提供了新的见解。
