Microscale Chloride Sensor

Abstract

Measurements of chloride concentration are important in a range of applications. We report here on our progress toward the fabrication and testing of small, inexpensive chloride sensors integrated with sensing electronics on a CMOS chip. We describe and demonstrate a process for formation of gold and silver chloride/ silver electrodes on a CMOS chip. Cyclic voltammetry is performed on chip-scale electrodes and the test results are discussed.

Development of Microelectrodes for Integrated CMOS Chemical Sensors

“…So it is swept from 1.51 V to -0.49 V and back to 1.51 V. The initial half-cell potential can also be calculated using the Nernst equation, which is +1.30 V for [5] and +1.31 V for [6]. These results indicate that the reduction of HClO starts at V i = −0.79 V and ClO¯ starts at −0.8 V. This is proved in Fig.4.…”

“…The second step is to form a silver/silver chloride layer on top of the gold layer of the reference electrodes. The details of this process are reported in (6). Finally the fused silica wafer was covered with Duco cement and epoxy to expose only the central portion of the pattern.…”