Modelling, characterization and testing of an ortho-planar micro-valve

Abstract

This paper presents the design, the realization and the modelling of an ortho-planar one-way microvalve that can be used in a micropump. The main advantages of such valves are that they are very compact and can be made from a single flat piece of material. An analytical model of the spring deflection has been developed and tested, and results are compared to Finite Elements Modelling. Several prototypes with a bore of 0.2 mm have been built using two manufacturing techniques, micro Electro Discharge Machining and stereo-lithography, and tested for a pressure up to 7 bars.

A simple check valve for microfluidic point of care diagnostics

“…While our valve design was inspired by past work, 8,11 the valves we present here have a number of distinguishing features. For example, unlike most previously reported orthoplanar springs used in microfluidic check valves, 8–10 the spring we incorporate is pre-stressed.…”

“…11 Our more versatile design enables pre-stressing of springs made from flat sheets of any flexible starting material. Previous orthoplanar spring check valves have been made from SU8, 8,11 stainless steel, 11 nickel, 9 and parylene C. 10 Here we present valves made from PET, PMMA, or both. Because we utilize thermoplastic materials, we can rapidly prototype mass-producible devices with integrated check valves using a CO 2 laser cutter and expect similar valve performance from late-stage assemblies produced by conventional machining or injection molding.…”

“…9,10 Smal et al improved upon the work of Nguyen et al by controlling the valve geometry to pre-stress the valves’ springs, thereby ensuring adequate sealing against reverse flow while preserving minimally impeded forward flow. 11 Here we pre-stress valve springs by placing a separate, soft elastomeric disc at the center of the spring while controlling the valve housing geometry. This innovation permits manufacture of robustly sealing check valves with springs patterned from flat sheets of thermoplastics rather than from photopolymers.…”

Fluid flow modelling of a micro-valve

“…Due to its quite simple processes and the relatively good mechanical properties, SU8 is used in many microfluidic applications. The detailed manufacturing procedure as well as manufacturing accuracy for these two methods are described in [11].…”

“…A previous paper [11] presents a detailed analysis, including design, manufacturing and modelling of the deformation, of the spider-spring used in our valve. In the present paper, we focus on the fluid flow modelling of the valve.…”