Miniature neurotransmitter sensors featured with iridium oxide nanorods

In this work, we reported fabrication of new miniature sensors utilizing iridium oxide (IrO₂) nanorods to improve the surface area for sensing. These sensors could be implanted to record neurotransmitter signals in the mammalian central nervous system. The IrO₂ nanorods were grown in an anodic aluminum oxide (AAO) nanotemplate using a chemical bath deposition method on the sensing area of the sensors. The nanorods with height of 200 nm and diameter of 80 - 100 nm as characterized by scanning electron microscope (SEM) were fabricated. Energy dispersive spectrometry (EDS) was used to verify the composition of the nanorods. In vitro experiments with dopamine demonstrated that the IrO₂ nanorod-based micro-sensors with an electrode size of 50×100 μm² achieved a sensitivity of 18 pA/μM.