Team:TU Eindhoven/Microfluidics/Methods

Methods

The fabrication of a microfluidic device is a two-step process where two types of lithography are involved. First the photolithography process is described and then soft lithography. Check our Protocol Page for more information about the precise processes.

Photolithography

The goal of photolithography is to create small features on a silicon wafer using a photoresist. The photoresist is spun on the silicon wafer with a spin coater. Different spin programs are used to get control over the height of the channels. To create the master mold for the droplet devices first a spin speed of 500 rpm is applied for 10 seconds after which the spin speed is ramped up with 330 rpm/s to a final speed of 1450 rpm and held for 30 seconds. This results in channels of 16 µm in height.

Figure 1. An overview of photolithography.

SU-8 2010 negative photoresist is used to create the master. After UV light exposure the SU-8 becomes insoluble due to crosslinking between the Bisphenol A epoxy oligomers. When developed the unexposed parts are dissolved leaving a pattern as is depicted in Figure 1. The used photomasks which have been used can be found in the Droplet Device or Cell Encapsulation Device Pages. The designes were all made in AutoCAD v2014.

Soft Litography

Figure 1. TU Eindhoven iGEM 2014 in a microfluidic device.

Bibliography

Song H, Chen DL, Ismagilov RF. Reactions in droplets in microfluidic channels. Angew Chem Int Ed Engl. 2006;45:7336–7356

Mazutis, L., Gilbert, J., Ung. W.L., Weitz, D.A., Griffiths, A.D. & Heyman J.A. (2013). Single-cell analysis and sorting using droplet-based microfluidics. Nature, 8(5), pp. 870-91.

Song H, Chen DL, Ismagilov RF. Reactions in droplets in microfluidic channels. Angew Chem Int Ed Engl. 2006;45:7336–7356