Analysis of Chloride Ion Sensor Modified by Graphene Oxide Under Microfluid Flow

Abstract

In this paper, we used a thermal evaporation system and a radio-frequency sputtering system to fabricate aluminum (Al) electrodes and indium–gallium–zinc oxide (IGZO) sensing membranes on the polyethylene terephthalate substrate. The IGZO/Al chloride ion sensor modified by graphene oxide has array sensing windows to avoid sensor malfunction. We used a screen printing technology to fabricate the sensor that made sensor a flexible structure. It can be adapted to many environments. The chloride ion sensor was immersed in the different concentrations of NaCl solutions from $10^{-5}$ to 1 M to measure the sensing characteristics of the chloride ion sensor. From the static measurement, the average sensitivity and linearity of the chlorine ion sensor were 60.536 mV/pCl and 0.973, respectively. We integrated microfluidic framework to measure the dynamic characteristic. From the dynamic measurement, we could know that the best average sensitivity and linearity of the chloride ion sensor for the flow rate of $20~\mu \text{L}$ /min were 64.639 mV/pCl and 0.972, respectively. To confirm the non-ideal effect of chloride ion, the hysteresis voltages of chloride ion in the different concentrations of NaCl solutions in two different cycles were 2.700 and 2.789 mV, respectively.