I upgraded the laser focusing lens on my laser cutter to a shorter focus length. The K40 laser cutters to not have  an adjustable focus, so that’s a bit of a pain, but it does make for more narrow cuts.

I also got some 1 mm thick acrylic sheets from aliexpress. I would link better, but the source is gone. It seems that sellers come and go quickly on that site.

I can make very shallow cuts in the thin acrylic, but they collapse during bonding. If I make channels deep enough in the material to avoid this, I end up cutting all the way through.

So, back to the 2 mm thick acrylic. If I make a deep channel in the 2mm acrylic, I get great results. If I do a shallow cut in the thick acrylic it still survives the bonding. The same cut parameters that collapsed in the thin sheets work fine in the thick acrylic. Weird.

Bottom line, I’m back in the acrylic microfluidic business (so to speak).