Collaborative Research: Capillary Micro-Switches for Actuation, Photonics and Manufacturing

毛细管表面是液体/气体或液体/液体界面，其形状由表面张力决定。 这种界面通常发生在1000微米或更小尺度的液体与气体之间，在这些尺度上，重力引起的变形可以忽略不计。毛细作用的使用已经成为在微观尺度上操纵液体的主要策略。然而，从业者还没有利用毛细血管不稳定性在这样的策略。 微型开关是亚毫米尺度上的配置，其表现出双稳态行为。 具有非线性响应的简单毛细管表面可以组合成“通-断”开关，正如我们最近所证明的那样。此外，在圆形开口处形成的毛细管表面可充当具有基本上零球面像差的微透镜。毛细管微透镜允许宽范围的波长。 例如，通过容纳紫外激光器，可以容易地访问100 nm尺度的特征，因此亚微米读写能力成为可能。另一个应用是在非平面表面上的远场光刻。在这里，具有可调节焦距的可单独寻址透镜阵列是关键。因此，微尺度的毛细管开关可用于聚焦和操纵光（光子学），以实现力或运动（致动），并实现高吞吐量生产（制造）。我们的目标是利用毛细系统的自然趋势，包括毛细不稳定性，以操纵它们的广泛应用。具体地说，我们将探索调整能量景观的方法，以便从配置A到B（以及从B到A）的变化可以由低能量扰动触发。 在极限情况下，毛细管开关可以设计成几乎可逆的，并且实施将导致功率高效的设备。毛细管系统中的触发状态变化可以通过机械（压力）、电（氧化还原表面活性剂）或热（热气动或Marangoni）手段发生。 将在数百微米和数十微米的尺度下检查各种刺激。

Capillary surfaces are liquid/gas or liquid/liquid interfaces whose shapes are determined by surface tension. Such interfaces generally occur for liquids against gas on scales of 1000 microns or less, scales where deformation by gravity is negligible. Use of capillarity has emerged as a leading strategy for manipulating liquids at the micro-scale. However, practitioners have yet to take advantage of capillary instabilities in such strategies. Micro-switches are configurations on the sub-millimeter scale that exhibit a bi-stable behavior. Simple capillary surfaces with nonlinear response can be combined to make an "on-off" switch, as we have recently demonstrated. Moreover, capillary surfaces formed at circular openings can act as micro-lenses having essentially zero spherical aberration. Capillary micro-lenses admit a wide range of wavelengths. For example, by accommodating uv-lasers, features at 100 nm scale may readily be accessed and hence sub-micron read-write capabilities become possible. Another application is far-field photo-lithography on non-planar surfaces. Here, an array of individually addressable lenses with adjustable focal lengths are the key. Therefore, capillary switches at the micro-scale can be used to focus and manipulate light (photonics), to effect force or motion (actuation) and to implement high through-put production (manufacturing). Our objective is to use the natural tendencies of capillary systems, including capillary instabilities, to manipulate them for a wide range of applications. Specifically, we will explore ways in which the energy landscape can be tuned so that a change from configuration A to B (and back from B to A) can be triggered by low energy disturbances. In the limit, capillary switches can be designed to be nearly reversible and implementation will lead to power-efficient devices.Triggering state changes in capillary systems can occur by mechanical (pressure), electrical (redox surfactants) or thermal (thermo-pneumatic or Marangoni) means. Various stimuli will be examined at a scale of hundreds of microns and at tens of microns.