提出了一种细胞培养池顶聚二甲基硅氧烷(PDMS)弹性膜驱动的样品更换方法, 用于减少样品更换所需的流体驱动部件和样品消耗。排出废液时, 关断样品贮存池与细胞培养池间微阀, 培养池中液体被微泵抽出, 池顶弹性膜随之塌陷; 塌陷至所需程度时关闭微泵及下游微阀, 开启所需样品贮存池与培养池间微阀, 新样品将被池顶弹性膜反弹产生的弹性力吸入培养池; 反复几次即可完成培养池内新旧样品更换。结合理论分析、有限元仿真和实验结果, 对影响样品更换效果的主要因素: 培养池顶弹性膜所受净压力、膜厚、样品贮存池到培养池微通道路径形状进行了优化。优化后选定膜厚为0.8 mm、微泵流量为1.67 mL/min、直线型微流道进行的实验显示其80 s左右即可完成90%以上样品更换, 样品消耗和培养池内流体剪切力分别小于相同换液率下原有样品更换方式的1/4和1/10。该方法可减少样品损失和微泵、微阀工作时间, 简化芯片系统结构、减少总质量和总功耗, 换液过程无需人工干预, 有利于系统的小型化和自动化, 尤其适用于我国目前的空间细胞培养芯片系统。

A sample replacement method base on the elastic force produced by the polydimethylsiloxane (PDMS) elastic membrane was established to reduce the fluid driving parts and sample consumption in the sample replacement. In the draining stage, the microvalve between sample reservoirs and cell culture pool was closed, the liquid in the cell culture pool was pumped out by using a micropump, and the elastic membrane at the top of the pool was collapsed. Once the elastic membrane was collapsed to a certain extent, the micropump and the microvalve between cell culture pool and sample waste reservoirs were closed, and the microvalve between cell culture pool and required sample reservoirs was opened immediately. The new sample would be taken into the pool by the elastic force generated from the elastic membrane bounce. The aforementioned steps were repeated several times and the sample wastes could be replaced. The main factors affecting the replacing effect, including the net pressure put on the top elastic membrane, the film thicknesses and the shape of the path from sample reservoirs to cell culture pool, were optimized according to the theoretical analysis, the finite element simulation and the experiment results. The optimal parameters are the film thickness to be 0.8 mm, the micropump flow rate 1.67 mL/min and the straight path, respectively. On the parameters mentioned above, more than 90% sample wastes are replaced within 80 s, meanwhile the sample consumption and fluid shear stress in the pool are less than 1/4 and 1/10 of the existing sample replacement system under the same replacing rate, respectively. The sample replacement method proposed shows its advantages on simple structure, low-sample/power consumption, and fewer-microchip mass, which is benefit to the miniaturization and automation of the space cell culture micro systems.