High-performance PCB-based capillary pumps for affordable point-of-care diagnostics

Capillary pumps are integral components of passive microfluidic devices. They can displace precise volumes of liquid, avoiding the need for external active components, providing a solution for sample preparation modules in Point-of-Care (PoC) diagnostic platforms. In this work, we describe a variety of high-performance capillary pump designs, suitable for the Lab-on-Printed-Circuit-Board technology (LoPCB). Pumps are fabricated entirely on Printed Circuit Board (PCB) substrates via commercially available manufacturing processes. We demonstrate the concept of LoPCB technology and detail the fabrication method of different architectures of PCB-based capillary pumps. The capillary pumps are combined with microfluidic channels of various hydraulic resistances and characterised experimentally for different micropillar shapes and minimum feature size. Their performance in terms of flow rate is reported. Due to the superhydrophilic properties of oxygen plasma treated FR-4 PCB substrate, the capillary pump flow rates are much higher (138 μL/min, for devices comprising micropillar arrays without preceding microchannel) than comparable devices based on glass, silicon or polymers. Finally, we comment on the technology's prospects, such as incorporating more complicated microfluidic networks that can be tailored for assays.