I would like to have a method for making a microfluidic chip in-house. In the end, I would like to make flow channels for rapid solution exchange around microscopic objects. I worked on something like this back in 2010 in the Chiu lab, but I don’t want to build up a photolithography setup (it’s rather expensive). I would also like to try to microfluidically generate droplets like Shim et. al. or even work from my colleagues in the Chiu lab.
How do you make microfluidics without lithography? I decided to try laser-cutting microchannels.
I used my laser cutter to etch channels in the surface of a piece of clear acrylic. Then I used the laser on a stronger setting to cut out a piece with the channels plus a second piece with through holes for access to the channels. I thermally bonded the two pieces of acrylic together. I used a cyanoacrylate gel glue (Loctite brand) to seal a 20 gauge blunt needle into those holes. I applied it around the needle barrel and then inserted the needle into the hole. I incubated the glue at ~30 °C for about 20 min to accelerate the cure. The result was a very good, liquid-tight seal.
I connected the device to a syringe pump with polyethylene tubing. The channel was able to carry flow up to the maximum flow rate of the syringe pump, 6 ml per min. The linear speed in the channel was on the order of .5 m/sec. I’m happy with that.
That’s step one. Hopefully droplets will not prove too hard to generate. When I tried this some years ago, they were a huge pain.