SIMPLE analytical model for smart microfluidic chip design

摘要

Precise control of the flow dynamics in a microfluidic device is of great importance for the integration of bioassays on-chip. Recently, the Self-powered Imbibing Microfluidic Pump by Liquid Encapsulation (SIMPLE) was developed in our group and integrated with biological applications. The system functions based on capillary imbibition of a working liquid (WL) into a porous material (PM), which in turn pulls a sample liquid (SL) through the connected microfluidic channel network. Analytical models describing the pumping dynamics of paper-based and channel-based systems have been presented, but no suitable analytical models have been reported for hybrid systems such as SIMPLE. Moreover, the available models were mostly limited to only describing the pumping process (i.e. flow rate) for given design parameters (i.e. paper shape, channels geometry), which still resulted in tedious trial-and-error process to optimize the chip design to achieve the desired flow rate. In this work, we developed a smart designing tool for SIMPLE-based chips that provides the design parameters necessary to obtain a targeted flow rate. An analytical model for the SIMPLE was first derived and validated, confirming its 3 main hypotheses: i) the sample flow rate is dependent on the porous material geometry but independent from the ii) porous material volume and iii) channel geometry. All experimental results were in good agreement with this model. Finally, we used our model as a prediction tool providing precise design parameters to avoid the time-consuming trial-and-error approach needed to achieve a specific flow rate. In particular, several chips were fabricated according to the model inputs and the sample liquid flow rates measured (1.5 +/- 0.3, 5.3 +/- 1.5, 15.2 +/- 2.7 mu L/min) were matching the targeted ones (1.5, 5, 15 mu L/min). The analytical model developed in this work was proven to be a useful designing tool for fast and efficient optimization of SIMPLE-based chips in order to addr