Life is simple at Reynolds numbers much below 0.1 Four 200 x 50 um inlet channels join into one 800 x 50 um main channel. The blue and clear liquids mix only by diffusion. See also here.

A test of the 8-channel 0-7 kPa microfluidic pressure controller today. We’re looking through a 100x inverted microscope. There’s a 2 um latex bead in a ~40 um wide channel formed between a glass coverslip and a PDMS layer. I’m hitting the keyboard to either increase or decrease the pressure in steps of +/-35 Pa [...]

I got some new microfluidic chips to play with today (courtesy of the Microfabrication Group at TKK). This must be cutting-edge research, since there’s an article about using laminar flow cells for single molecule experiments in the latest issue of Nature Methods. I’m testing our custom-built pressure controller which controls the inlet and outlet pressures [...]

This 8-channel pressure-gauge card is a step towards proper control of fluid flow in microfluidic devices. The transducers (0-1 psi) are around 30 eur each and made by Honeywell. The mV-level signal from a Wheatstone bridge in the transducer is amplified by an instrumentation amplifier (INA111) to around 0-10 V for input to a 16-bit [...]

I’ve been playing around with a microfluidic channel, to be used with optical tweezers experiments later. There’s clear fluid coming in from the left in the wide (ca 30um) channel, and I’ve colored the fluid from the top red and the fluid coming in from the bottom blue. The top and bottom channels are narrower, [...]