Digital Light Processing Printing ‐ Cadworks ProFluidics 285D Microfluidics Printer - VT-DISCO-LAB/Getting-Started-in-the-Discovery-Lab GitHub Wiki

Photo of the Discovery Lab's Microfluidics Printer

When to Use

Our Cadworks DLP 3D printer is able to create precise and high-resolution parts/chips for microfluidics. Two types of resins are available to Discovery Lab Users - "Mastermold" for PDMS part fabrication and "clear" for encapsulated device fabrication.

The Discovery Lab's Formlabs Form 4 SLA printer is able to handle the manufacture of light-duty microfluidics. HOWEVER the Cadworks DLP printer is able to producer higher resolution materials and the resins use have lower viscosity and able to produce parts with smoother surfaces.

The DLP Printer is ideal for prototyping high-resolution printing of micro-sized features and "lab-on-a-chip systems".

Benefits of the Discovery Lab's DLP Printer

  • High Resolution and detail
  • Produces smooth surface parts / chips
  • Produces optically clear prints
  • Produces fully solid parts
  • Can print small and precise small-diameter channels with high aspect ratios
  • Purpose-build for micro fluidics work

Weaknesses

  • Higher costs for materials
  • CADworks two proprietary resins are the only material options

Printer Specifications

  • Build Volume: 110 (length) x 62 (width) x 120 (height) mm
  • Suggested Part Aspect Ration 5:1 (add outside corner fillets if working at/near/above this value)
  • Pixel Size 40µm native, 28.5µm dynamic
  • Wavelength 385 nm
  • Z-Height Resolution 5-500µm
  • Commonly Printed Z-Heights 50µm OR 30µm
  • Minimum Suggested Encapsulated Channel Diameter (clear Resin) 80µm

Materials

"Mastermold" for PDMS molding applications, "Clear" for direct-use microfluidic applications (biocompatible, inert under florescent light)

MasterMold MasterMold by CADworks3D is a specialized resin designed for creating high-resolution master molds for PDMS microfluidic Ideal for creating PDMS molds with features as small as 50µm. It provides a fine surface finish (0.18µm Ra value) that ensures optical clarity, proper bonding, and prevents leaking during testing. When casting PDMS, no cytotoxic residual material is transferred, making it biocompatible and suitable for cell culture applications. NOTE: Master molds can withstand lab oven temperatures and can be used multiple times to cast up to 500 PDMS devices.

Clear Microfluidics Resin This resin is specially formulated with low viscosity for easy drainage of enclosed channels during printing and cleaning. This resin enables precise, high-resolution printing of micro-sized features, making it ideal for prototyping and lab-on-a-chip applications.

The resin is also specifically developed for maximum biocompatibility, and optical clarity. The material is also inert under florescent lighting.

Design Resources

  • Looking for more guidance on how to get started designing your part / chip? "This video from Parallel Fluidics" gives a comprehensive overview on how to design a part / chip in Solidworks CAD.

*[3DuF] (https://3duf.org/) is an open-source web-based design tool for microfluidics design.

Tips for Microfluidic Part / Chip Design

Templates to get you started

We recommend that you select one of these files to get started with your design.

Standardize part input/output holes to access the flow and control channels punchers

Fluids and control pressures are introduced by pushing either steel pins + Tygon tubing or PEEK/PE tubing into inlet/outlet holes. 20 gauge holes are standard (0.66 mm diameter, 1 mm radial channel “wagon wheel” design in AutoCAD). Use small (0.3 mm diameter) holes without “wagon wheel” if you want to introduce or collect stuff (beads, cells, worms)

**Have a minimum of 2 mm between inputs and outputs.

Remember the 1 to 10 rule

Channels in microfluidic parts/chips are typically rectangular cross sections - 10µm deep, 100s of µm wide, and 1000s µm long.

Keep structures to an aspect ratio no lower than 1:10 (height : width)

Structures with lower aspect ratios are prone to collapse. If a feature is wider than this design rule permits, support posts must be added to ensure the aspect ratio is no lower than 1:10 in between posts (i.e. posts every 100um for a 10um high structure). If your device does not call for valves (i.e. it is a simple single layer device), it is not as prone to collapses and lower aspect ratio can be used.

If you don’t have any real constraints, a great place to start is channels that are 100 um wide by 20 um tall.

All devices must be designed with a border indicating where the chip should be cut NOTE: For PDMS manufacture, you mush have a minimum of 2-3mm between the part/chip and where you will cut.

Consider the size of your substrate Make sure that your designs fit within your substrate (microscope slide, coverslips, etc.) and leave a minimum of 1-2 mm gap to the edge of each substrate. You can have a construction layer dedicated to the substrates.

Design must incorporate sufficient tolerance to allow for easy layer/layer registration

Designs must account for alignment tolerances of 30um. This means that the device must be designed to function properly despite 30um errors in alignment in all directions.

All multi-layer/multi-height devices must have alignment marks

Avoid sharp corners

Think about potential dead-volumes and features that can capture bubbles.

Part / Chip Thickness

DLP prints are best kept small to small/medium scale, with wall thicknesses between 1-5mm. Thicker parts may result in surface imperfections like rashing or ragging and can lead to dimensional inconsistencies. A minimum wall thickness of 0.5mm is recommended to ensure structural integrity.

Support Structure

Parts can be, and are typically printed directly on the build plate but they may also be elevated using support structures. Printing directly on the build plate will usually cause a subtle defect at the outside edge along the base known as "elephant’s foot." Support structures are necessary for stabilizing parts with overhangs during printing (much like SLA/MSLA). The contact points of the supports may leave small defects that can be sanded down for a smooth finish.

##Preparing Your Files for Printing The Discovery Lab team recommends you prepare two sets of files for each part/chip you are looking to manufacture - 1) Original Parametric Model (Solidworks/Inventor/Fusion360/etc) and a millimeter scale STL file (point mesh file).

Additional Resources