Single-mask fabrication of micro-probe electrode array with various tip heights and sharpness using isotropic and anisotropic etching
In this work, a silicon-based micro-probe array was fabricated using multi-step deep reactive ion etching (DRIE) and reactive ion etching (RIE) processes. The micro-probe structure was implemented using a micromachining technique through a combination of two anisotropic DRIE and two isotropic RIE processes with a single etch mask. The cone-shaped tip height and tapered tip-end angle were experimentally varied with respect to the first DRIE depth. As the first DRIE depth was decreased, the micro-probe tip height increased and the sharpness consequently improved. The conductive layer was exposed only at the tip ends of the micro-probe to form a conical ultra-micro electrode, and it was characterised via cyclic voltammetry measurements.
