A simple check valve for microfluidic point of care diagnostics

Abstract

Check valves are often essential components in microfluidic devices, enabling automated sample processing for diagnostics at the point of care. However, there is an unmet need for a check valve design that is compatible with rigid thermoplastic devices during all stages of development—from initial prototyping with a laser cutter to final production with injection molding. Here, we present simple designs for a passive, normally closed check valve that is manufactured from commonly available materials with a CO2 laser and readily integrated into prototype and production thermoplastic devices. The check valve consists of a thermoplastic planar spring and a soft elastomeric pad that act together to seal against fluid backflow. The valve’s cracking pressure can be tuned by modifying the spring’s planar geometry and thickness. Seal integrity is improved with the addition of a raised annular boss beneath the elastomeric pad. To demonstrate the valve’s usefulness, we employ these valves to create a finger-operated on-chip reagent reservoir and a finger-actuated pneumatic pump. We also apply this check valve to passively seal a device to enable portable detection of RNA from West Nile virus in a laser-cut device.

Multi-step PDMS curing and a controlled separation method for mass manufacturing of high-performance and user-friendly micro-devices: valved micropumps

“…Valved micropumps can be driven in lots of ways, and are very flexible for various applications. For example, in point-of-care diagnostic devices, 44 finger pressing is a very convenient power source. We integrated the micropump into the chip and observed its fluid driving ability by finger pressing (Fig.…”

Loop-mediated isothermal amplification (LAMP) – review and classification of methods for sequence-specific detection

“…73 Technical applications of QUASR on a chip and with smartphone readout are described elsewhere. [74][75][76] The analytical sensitivity for detection of cell-cultured zika virus by QUASR RT-LAMP was 44 copies per reaction. Furthermore, the assay showed high analytical specicity when tested against other aviviruses and alphaviruses.…”

Smartphone-Based Point-of-Care Microfluidic Platform Fabricated with a ZnO Nanorod Template for Colorimetric Virus Detection

“…Herein, we report a POC virus detection platform by combining nanostructure-integrated polydimethylsiloxane (PDMS) microfluidics with colorimetric detection. PDMS is environmentally friendly and frequently used in POC devices. ,− Laboratory and field measurements demonstrate that PDMS does not bioaccumulate . Nanostructures are commonly used to increase surface area. − Compared to the flat surface, the three-dimensional (3D) nanostructures can provide more binding sites for probes and offer topological and morphological features to encourage the interaction between surface probes and detecting targets. − Moreover, the diffusion distance is efficiently reduced for detecting targets and surface probes within the nanostructures. , Normally, the PDMS surface from the replica is flat at the nanoscale.…”