Evaluation of SIROF Microelectrodes for Single Neuron Stimulation in Biohybrid Circuits

Microelectrodes with an upper functional layer of dc sputtered iridium oxide film (SIROF) are intended to be applied in biohybrid circuits for single insect neuron stimulation. In this paper, we report on electrochemical evaluation and of planar disc microelectrodes of varying size (diameter of 10 to 300 μm) and their charge injection properties of SIROF at microelectrode level during fast current pulses. The pulse injection charge (Q
_inj
) limits represent only a fraction of the charge storage capacity (Q
_csc
) measured by cyclic voltammetry. Electrodes with diameter down to 100 μm and 80-100mC.cm
^-2
oxide charge capacity sustain about 2 mC.cm
^-2
in pulse mode, while the maximum charge injection per phase for d=10 μm electrodes the respective values were Qcsc = 892.6 mC.cm
^-2
and Q
_inj
= 9.1 mC.cm
^-2
.