Electrodes Microfluidics System for Microbio Object Analysis

We have designed and fabricated an electrode microfluidics system for microbio object analysis. Two parallel-plate electrodes were fabricated using the soft lithography technique integrated with a polydimethylsiloxane (PDMS) microfluidics channel. Gold (Au) material was decomposed to fabricate the electrodes. The voltage response through the charging and discharging of the electrodes was observed using an oscilloscope. For a constant dc voltage of 5 V we obtained a time constant for the electrodes of 3.6 ms. On the other hand, it requires 850 ms to discharge completely without an external load. The capacitance of the electrodes in air (room environment) is 0.39 pF. Due to the higher dielectric constant of distilled water (80.1), in the water medium the electrode capacitance is 0.77 pF. We also measured the capacitance of the electrodes by changing the medium to microbio objects such as yeast cells (5 pF) and live bacteria cells (30 pF). The results showed that bacteria have a higher electrical capacitance than yeast.