Transfer characteristics of dynamic biochemical signals in non-reversing pulsatile flows in a shallow Y-shaped microfluidic channel: signal filtering and nonlinear amplitude-frequency modulation

The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.

基于时空浓度梯度反演扁平微通道中平均流速的优化算法

微流控通道内流速的准确测量在利用微流控芯片开展定量化学分析、样品制备、药物合成等领域具有重要应用价值。基于物质输运原理,提出了一种通过测量物质时空浓度梯度反演扁平微通道中平均流速的优化算法。首先,基于Navier-Stokes方程与Taylor-Aris弥散方程建立扁平微通道中速度场与浓度场的定量关系,分别提出了用直接反演法和优化算法求解平均流速的方法;其次,通过数值仿真系统地分析了时空浓度变化频率、振幅和扩散系数对反演流速准确度的影响;最后,通过荧光素实验验证了该方法的可行性。结果表明:无噪声情况下,优化算法反演结果与真实速度相关系数为1,具有很高的精度;有噪声情况下,增大物质浓度信号的频率与振幅、采用扩散系数较小的物质有助于提高算法的准确度;在微流控装置中,优化算法反演结果与流量传感器测量计算结果的相关系数为0.9814。

Dispersion of Dynamic Biochemical Signals in Steady Flow in a Shallow Y-type Microfluidic Channel

This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type microchannel from two inlets.The transfer function for the Y-type microchannel is given by solving the governing equation for the Taylor-Aris dispersion in the microchannel. The amplitude-frequency and phase-frequency relations are provided which show that a shallow Y-type microchannel acts as a low-pass filter. The transports of different dynamic biochemical signals are investigated. In comparison with a fully mixing microfluidic channel, the magnitudes of the dynamic signals at the outlets in a Y-type microchannel are much smaller than those in a fully mixing microchannel, which demonstrates that the amplitude attenuation in a Y-type microchannel is larger than that of a fully mixing microchannel due to the transverse molecular diffusion. In order to control the desired signal in a microchannel, the solution of the inverse problem for the channel is also presented.

一种用于精子分离的微流控芯片

快速有效地分离出活性精子,对成功受孕和婴儿健康至关重要。传统分离精子的方法容易损坏精子、价格昂贵。而微流控技术的出现为精子分离提供了有效的平台,该文利用层流和精子趋化性原理,设计了一种X-型的微流控芯片。利用分离变量法,对含有生化因子的定常流的对流-扩散方程进行精确求解,获得了生化因子在通道内的浓度分布情况。此外,基于层流和精子趋化性原理,利用该芯片对精子的分离进行了初步研究。