Characterizing and isolating microparticles of different sizes is often desirable and essential for biological analysis. In this work, we present a new and straightforward technique to fabricate variable-height glass microchannels for size-based passive trapping of microparticles. The fabrication technique uses controlled non-uniform exposure to an etchant solution to create channels of arbitrary height that vary in a predetermined way from the inlet to the outlet. Channels that vary from 1 μm to over 20 μm in height along a length of approximately 6 cm are shown to effectively and reproducibly separate particles by size including particles whose diameters differ by less than 100 nm when the standard deviation in size is less than 0.66 μm. Additionally, healthy red blood cells and red blood cells chemically modified with glutaraldehyde to reduce their deformability were introduced into different channels. The healthy cells can flow into shallower heights, while the less deformable ones are trapped at deeper heights. The macroscopic visualization of microparticle separation in these devices in addition to their ease of use, simple fabrication, low cost, and small size suggest their viability in the final detection step of many bead-based assay protocols.

中文翻译：

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高度可变的通道，用于表征和显示微粒。

表征和分离不同尺寸的微粒通常是生物学分析所需要的，也是必不可少的。在这项工作中，我们提出了一种新的直接技术来制造高度可变的玻璃微通道，以用于基于尺寸的微粒的被动捕集。该制造技术使用对蚀刻剂溶液的受控不均匀暴露来创建任意高度的通道，该通道以预定方式从入口到出口变化。沿长度约6 cm的高度从1μm到超过20μm的通道显示可有效且可重现地按尺寸分离颗粒，包括尺寸标准偏差小于0.66μm时直径差异小于100 nm的颗粒。另外，健康的红细胞和经戊二醛化学修饰以降低其变形能力的红细胞被引入不同的通道。健康细胞可以流入较浅的高度，而变形程度较小的细胞则被困在较高的高度。这些装置的易用性，简单的制造，低成本和小尺寸使其在宏观上可视化了这些装置中的微粒分离，这表明它们在许多基于微珠的检测方案的最终检测步骤中均具有可行性。