Fabrication of ITO microelectrodes and electrode arrays using low-cost CO2 laser plotter

Excellent electronic and optical properties make indium tin oxide (ITO) an attractive electrode substrate. Despite the commercial availability of high-quality ITO and some low-cost methods for direct deposition being in use by now, the definition of patterns is still a concern. Putting its popularity and extensive usage aside, the manufacturing of ITO electrodes so far lacks a rapid, highly reproducible, flexible, cost-effective, easy patterning process that could surpass difficult, time-consuming techniques such as lithography. A cost-effective method based on CO2 laser irradiation for preparing ITO microelectrodes and electrode arrays is presented herein. Electrodes of different sizes and shapes were examined to identify the performance of the proposed methods. Direct ablation of the ITO layer was optimized for rectangular electrodes of 25, 50, and 100 µm width, while laser cutting of scotch tape stencils and subsequent wet etching were used to create circular electrodes with a diameter of 1.75mm. Together, both methods form a complete toolbox, which allows for low-cost and fast fabrication of ITO electrodes for wide variety of applications. A multielectrode array system consisting 8 of these circular electrodes was fashioned, fabricated, assembled and tested. The ITO electrodes were characterized electrochemically and as an example application they were used for monitoring anchoring behavior of HeLa and HepG2 cell cultures through cell-based electrochemical impedance technique.