Impedance-based response of an electrolytic gas bubble to pressure in microfluidic channels

In this paper we have electrically measured the response of electrolytic gas bubbles to varying pressures in a microfluidic channel. Impedance measurements were used to monitor either the volume or volume change of an electrolytic bubble. Experimental results show that both the bubble size and bubble dissolution rate are sensitive to the applied pressure, and can be readily measured in the fluidic channel. The bubble response to pressures ranging from 101.3 (1 atm) to 112.7 kPa was characterized. Various surface wettabilities were tested, and results show that in a microfluidic channel surface-free energies at the solid-liquid-gas interfaces play an important role in the measured response. Results provide an electrical measurement approach towards pressure or flow rate sensing in microfluidic systems using electrolytic gas bubbles.