Universal Microcarriers for Microfluidic Assays

Bead and cell suspension based flow-through assays are popular for high throughput biological analysis. Several technologies incorporate a tagging scheme with beads to enable multiplexing. Modern flow-through systems such as flow cytometers and cell sorters are large, bulky and expensive; consequently, much research has been performed using microfluidics to miniaturize these systems. However, several problems remain with these systems, notably it remains difficult to perform manipulations on the beads (or cells), and in the case of multiplexed systems, it remains difficult to read the tags quickly. In this paper, we present a micromachined micro-carrier, referred to as a ‘micropallet’, designed to move through a microfluidic device, which helps to solve several of these problems. Micropallets are small carrier structures, micromachined out of plastic or other materials, that are used to carry attached biological or chemical samples through a microfluidic system (e.g., DNA, RNA, proteins, antibodies, adherent cells, organisms). Similar to conventional factory pallets that carry a product through an automated manufacturing line, micropallets are engineered to carry their cargo through a micro-scale system. Thus micropallets may contain shapes, structures and materials designed to interact with and work in a microfluidic system, such as for docking, sorting, manipulation and readout. Additionally, micropallets may include bar codes or other markings, and be engineered to optimally suit the cargo they carry (for example, a micropallet might contain 3-D structures and treated sections for cells, molecules or organisms to attach). Results are presented for the use of micropallets in cell assays, DNA assays and antibody assays. Micropallets may be designed to carry a sample through a microfluidic system or for use in a static assay system, enabling versatile customisation of the micropallets and flow system for design of a programmable system that interacts with the micropallets for detection, control and manipulation.