School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen 518055, China.
School of Science, Harbin Institute of Technology, Shenzhen 518055, China.
Biosensors (Basel). 2022 Oct 13;12(10):868. doi: 10.3390/bios12100868.
Generating and maintaining the concentration dilutions of diffusible molecules in microchannels is critical for high-throughput chemical and biological analysis. Conventional serial network microfluidic technologies can generate high orders of arbitrary concentrations by a predefined microchannel network. However, a previous design requires a large occupancy area and is unable to dynamically generate different profiles in the same chip, limiting its applications. This study developed a microfluidic device enabling dynamic variations of both the concentration in the same channel and the concentration distribution in multiple channels by adjusting the flow resistance using programmable pneumatic microvalves. The key component (the pneumatic microvalve) allowed dynamic adjustment of the concentration profile but occupied a tiny space. Additionally, a Matlab program was developed to calculate the flow rates and flow resistance of various sections of the device, which provided theoretical guidance for dimension design. investigations were conducted to evaluate the microvalve deformation with widths from 100 to 300 µm and membrane thicknesses of 20 and 30 µm under the activation pressures between 0 and 2000 mbar. The flow resistance of the deformed valve was studied both numerically and experimentally and an empirical model for valve flow resistance with the form of Rh=aebP was proposed. Afterward, the fluid flow in the valve region was characterized using Micro PIV to further demonstrate the adjustment mechanism of the flow resistance. Then, the herringbone structures were employed for fast mixing to allow both quick variation of concentration and minor space usage of the channel network. Finally, an empirical formula-supported computational program was developed to provide the activation pressures required for the specific concentration profile. Both linear (Ck = -0.2 + 1) and nonlinear (Ck = (110)k) concentration distribution in four channels were varied using the same device by adjusting microvalves. The device demonstrated the capability to control the concentration profile dynamically in a small space, offering superior application potentials in analytical chemistry, drug screening, and cell biology research.
在微通道中生成和维持扩散分子的浓度稀释是高通量化学和生物分析的关键。传统的串行网络微流控技术可以通过预定的微通道网络生成任意阶的高浓度。然而，以前的设计需要较大的占用面积，并且无法在同一芯片上动态生成不同的浓度分布，限制了其应用。本研究开发了一种微流控装置，通过使用可编程气动微阀调整流动阻力，能够在同一通道中动态变化浓度，并在多个通道中动态变化浓度分布。关键组件（气动微阀）允许动态调整浓度分布，但占用空间极小。此外，还开发了一个 Matlab 程序来计算设备各部分的流量和流动阻力，为尺寸设计提供了理论指导。研究了在激活压力为 0 至 2000 mbar 时，宽度为 100 至 300 µm、膜厚为 20 和 30 µm 的微阀的变形情况。对变形阀的流动阻力进行了数值和实验研究，并提出了阀流动阻力的 Rh=aebP 形式的经验模型。然后，使用 Micro PIV 对阀区的流体流动进行了表征，进一步证明了流动阻力的调节机制。接着，采用人字形结构进行快速混合，实现了浓度的快速变化和通道网络占用空间的减小。最后，开发了一个经验公式支持的计算程序，为特定的浓度分布提供所需的激活压力。通过调整微阀，使用同一装置实现了四个通道中线性（Ck = -0.2 + 1）和非线性（Ck = (110)k）浓度分布的变化。该装置展示了在小空间内动态控制浓度分布的能力，在分析化学、药物筛选和细胞生物学研究等领域具有优越的应用潜力。
