3D Printing for Microfluidics
Prototyping small volumes of microfluidic parts has traditionally been difficult using CNC machining or injection moulding, but Protolabs offers microfluidic fabrication through 3D printing for just this.
Microfluidics typically requires very flat surfaces, and clear and thin/shallow features that are difficult to produce in a mould that is milled and hand polished. These tiny features are not easily distinguishable, requiring careful polishing and injection moulding pressures can sometimes role the edges ever further, not to mention the effect that the ejector pins have on the part surface. Ejector pins play a huge factor in removing the part from the mould, and can cosmetically impact microfluidic parts that are moulded. We will continue to injection mould microfluidics, but please first discuss these projects with a customer service engineer at Protolabs.
An Additive Approach
3D printing microfluidics changes all of this as ejector pins are a non-factor. We use stereolithography (SL) to produce parts using an ultraviolet laser drawing on the surface of a thermoset resin, primarily our Somos WaterShed XC 11122 material. High-resolution SL is able to produce features as thin as 0.05 mm layers to provide the fine detail that microfluidics require. We recommend channel sizes of 0.64 mm square cross sections with a minimum wall thickness of 0.1 mm for X and Y dimensions and 0.4 mm for the Z dimension. Of course, we can produce features smaller than this, but it would need to be carefully reviewed by our engineers before the build begins.
Whether you’re creating a microfluidic part for a med device or have a new lens design, be sure to explain your concerns as we can create a special build to produce the clarity required for these parts. Protolabs uses a substrate build on a sheet of clear acrylic that provides a surface that requires minimal polishing. These down faces don’t have the support structures typically required using SL, so these surfaces will have your highest clarity. The up facing surfaces would have the next best finish followed by any vertical surfaces. To provide optimal clarity, the surfaces are then sanded down or polished to remove any visible layers on the flat surfaces. Not that on lenses and clear parts only (not on microfluidic parts), we do apply a clear urethane coating that improves on the clarity of the parts.
If you intend to create a new microfluidic part or require fine details with a clear surface, we strongly encourage you take a look at high-resolution SL for microfluidic fabrication as it may dramatically shorten your development time and reduce the potential high cost of moulding modifications if the design isn’t right the first time.
Learn more about microfluidics at protolabs.co.uk or contact one of our customer service engineers at [email protected] or +44 (0) 1952 683047.