Micro (really mili) Fluidic Device

by rbatzer

Micro fluidic devices are an emerging topic in Mechanical Engineering and have many applications in chemistry, biology, and medicine. The goal of this project was to create a larger micro fluidic device from silicone to demonstrate some of the properties of low Reynolds number flows  without a microscope.

A few mili fluidic devices I made in 2.674 are below. They are fabricated with UV curing epoxy on glass which are both stiff materials, so they will not work for a soft device as required by the project.

Micro fluidic devices are usually fabricated with PDMS which is flexible, but the PDMS is bonded to glass to make the structure rigid. I did not have access to PDMS for this project, so I decided to use the DragonSkin silicone provided by the class as my base material.

My first test used straws to create a hole in a silicone part. This worked well to make a passage, but allowed for only  very limited geometry.

The channels needs to be produced in a two part mold for more intricate geometries.

In the conventional method, the PDMS is bonded to glass by exposing both surfaces to an oxygen plasma and the same process should work for silicone. Cured silicone is nearly impossible to bond to by conventional means, to the plasma treatment was a reasonable option.

I modeled the channels I wanted to make in SolidWorks and machined the mold for the silicone on a CNC mill.  I then molded the silicone in the mold and a flat panel for the top as seen below.

The plasma chamber pictured below was used to prepare the surface for bonding. The purple seen through the chamber window is the plasma. Unfortunately, the silicone did not bond.