Fabrication and Modeling of a Capacitor Microfluidically Tuned by Water

This letter presents fabrication and modeling of a continuously tunable microfluidic capacitor, which is composed of electrodes obtained by classical electrodeposition and microfluidic channels generated by lamination of SU-8 films. We show that the capacitance increases continuously between C
_min
= 0.52 pF and C
_max
= 18.5 pF following addition of deionized (DI) water in microchannels. The capacitance tuning range reaches 3460% at 500 MHz. The quality factor decreases from Q
_max
= 69 when the capacitor is empty to Q
_min
= 5.3 when it is fully filled with DI water. We also model the electric field and current distributions inside microfluidic channels, showing that electric field is cancelled as they are entirely filled with DI water.