Flow rate determination in capillary-driven microfluidics using combinatorial selection of resistors via electrowetting and smartphone control

We present a programmable hydraulic resistor array to set flow rates post-fabrication in capillary-driven microfluidics. We specifically show an array composed of 7 parallel resistors and 14 electrogates. “Electrogates” consist in a geometric deformation (i.e. a trench) allowing to stop a liquid by pinning at the edge of the trench and to resume it using electrowetting. The resistor array is controlled using a smartphone connected to a peripheral. We showed that such a resistor array can modulate flow rates by a factor 21 and as an illustration of this concept we modulate enzymatic reactions in microfluidic chips.