D. Purcell, J. McFall, A. Pawar, H. Islam, W. Lopez, T. Huang, P. Nath
Los Alamos National Laboratory,
Keywords: microfluidics, lab-on-a-chip, micro-pump
Summary:In the development of Lab on a chip applications, microfluidic pumps play an important role in miniaturizing and integrating multiple laboratory steps into a single platform. In this work, we present a method of manufacturing and integrating magnetically-actuated, microfluidic peristaltic pumps with special attention to driver technology, integration, automation, and deployment. The pump is composed of two units: (1) driver disc, and (2) microfluidic card – both containing embedded permanent magnets as shown in Fig 1. When the driver disc is rotated at a given rpm (revolution per minute), magnetic interactions between the driver disc and microfluidic card causes a membrane in the microfluidic card to actuate in a peristaltic motion resulting into positive displacement of a fluid (Fig 2). The microfluidic card and the driver disc were fabricated using a laser based micro-patterning and lamination of polymer film/sheet. The disc was rotated and controlled using a stepper motor (Fig 3). Unlike typical microfluidic pumps1,2, this approach introduces several new features for pumping in microfluidic systems: • Scalability: The number and size of magnets can be varied to obtain a range of flowrates to fit a given application. In this work, we have demonstrated proof of principle using a 3 and 4-magnet systems with 500 by 125 microns channels and 4.8 mm diameter magnets. Flowrates ranging between 50 - 1500 microliters/min were obtained for a driver rotation speed ranging 10-100 rpm. • Head pressure: The design of the pump yields itself to creating a high head pressure, as the magnetic force that actuate downward into the flow channel can create a strong resistance to backflow. A multi-physics finite element analysis model is used to determine the optimal number of magnets needed to obtain the highest back-pressure for a given set of geometric parameters. • Parallelization: A single driver can be used to operate multiple pumps when strategically laid out on the microfluidic card. Fig 4 shows a setup which was used to operate three pumps simultaneously to generate a series of plug flow using oil and food coloring dye. Additionally, it is possible to create flow in different directions (‘withdraw’ or ‘infusion’) by designing the magnet orientations within the microfluidic card, while the driver rotates in one direction. We have demonstrated that the planar peristaltic pumps and driver technology has the ability to produce a wide variety of flow rates while operating multiple units in parallel fashion with a singular driver. We envision great potential for a new method of integrating these pumps into lab-on-a-chip platforms.