Microfabrication of WO3-based microelectrochemical devices

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Abstract
A new photolithographic process for the patterning of WO3 is reported. A layer of sputtered polycrystalline WO3 can be patterned by a combination of photolithographic and dry etching processes to selectively cover a fraction of eight Pt microelectrodes each ∼50 μm long, 2 μm wide, and 0.3 μm thick, and spaced 1.2 μm apart. The modified microelectrode arrays were characterized by electrochemistry, surface profilometry, and scanning electron microscopy. A pair of microelectrodes connected by WO3 comprises a microelectrochemical transistor with pH‐dependent electrical characteristics based on the pH and potential dependent conductivity of WO3 associated with the reversible electrochemical reaction WO3+nH++ne−⇄HnWO3.