Disposable miniature check valve design suitable for scalable manufacturing

Abstract

We present a passive, miniature check valve which can be manufactured using standard techniques ideal for low-cost, disposable systems used in medical devices and other applications. The body of the valve consists of a hollow cylindrical core, closed at one end, with a side port and a cylindrical elastomeric sleeve placed over the core body, covering the side port. The pressure required for initial opening of the valve, referred to as cracking pressure, can be adjusted, and depends predominantly on the valve core outer diameter, the sleeve inner diameter, the sleeve wall thickness, and the sleeve material’s modulus of elasticity. These parameters can be controlled to tight tolerances, while the tolerances on other features can be relaxed, which simplifies valve manufacturing and assembly. Valve embodiments produced from different materials, and with varying critical dimensions, exhibited distinct and reproducible cracking pressures in the range of 2 to 20 PSI. The cracking pressure did not vary significantly as a function of flow rate. No back flow leakage was encountered up to 30 PSI, the pressure limit of the sensor used in this experiment. Most of the valves tested had small internal volumes of 3–4 μL. The internal volume can be further reduced by selecting a core of smaller inner diameter. In contrast to lithography-based microvalves that generally must be manufactured in-situ within the fluidic device, the herein presented valve can be manufactured independently of, and can be readily integrated into fluidic systems manufactured via a wide selection of fabrication methods.

Integrated nucleic acid testing system to enable TB diagnosis in peripheral settings

“…Four mL of a 1:5 dilution of the supplied 1X PureLyse® wash buffer was injected into the wash chamber, while 275μL of the PureLyse® elution buffer supplied with the PureLyse® Kit (Claremont BioSolutions) were injected into the elution chamber, in each case by piercing through the polycarbonate film covering the chambers and then resealing the hole with epoxy. The polypropylene reaction insert was assembled by inserting custom check valves 43 into the inlet and outlet conduits, placing two reagent pads containing lyophilized master mix components (described below) into the dome-shaped reaction chamber on the underside of the insert body, and then sealing the circular reaction chamber by thermally bonding a polypropylene film to the bottom of the insert body. A tear shaped pump pouch covering the reaction chamber and the bottom opening of the pump conduit was formed by thermally bonding another polypropylene film to the bottom of the reaction insert, and then filling the pump pouch with silicone oil (viscosity 5cSt).…”

“…The reaction pouch can be accessed through an inlet and an outlet port, which contain miniature, inexpensive check valves 43 in anti-parallel orientation to control unidirectional flow. The pump pouch that overlays the reaction pouch is filled with thermally conductive fluid to facilitate heat transfer to the reaction chamber, 47 and is connected to the fourth ePump.…”

Parametric design, fabrication and validation of one-way polymeric valves for artificial sphincters

“…The results reported in this paper permit the design of a polymeric valve showing specific performances in terms of OP. The valve profile has been described by univocally defining the correspondent parameters (these details, in many articles, are partial, omitted, or described in a non parametric manner) [9,10,16,18,19]. Another important novelty compared to the state-of-the-art is the accurate parameter analysis, conducted with the aim of highlighting which parameters were more significant for valve performance.…”

“…The reported results may be exploited for many applications that require specific valve performance. However, they are not usable as components for artificial urinary sphincters, due to the high pressure range (12 kPa-120 kPa) and to the small flow rates [18].…”

A simple check valve for microfluidic point of care diagnostics

“…4 While these valves are passive, their manufacture requires significant investments and expertise to achieve the tight tolerances necessary to avoid either leaks or unintentionally high cracking pressures. Similarly, recently proposed designs for terminal check valves and bridge check valves for a lab on a disc, 5 tube and sleeve check valves, 6 and elastic slit check valves 7 rely on elastomeric materials being precisely stretched during installation to avoid leaks or blockages. In our hands, such valve types have a high failure rate during initial design testing due to slight variations in material thicknesses and housing assembly, limiting their usefulness for prototyping.…”