We report a novel low-cost and simple technique to fabricate micron-scaled pH sensors using Pd patterned structures. We utilized a combination of photolithography and a lift-off technique to fabricate a V-shaped 4-probe device from a continuous Pd film. The device could detect the pH of a buffer solution by electrolysis. The hydrogen gas (H(2)) in the solution generated during electrolysis was sensed by the Pd structure. Our results demonstrate that micron-scaled pH sensors based on V-shaped Pd structures can be used to quantitatively detect the pH of a wide pH range of buffer solutions. (C) 2009 Elsevier B.V. All rights reserved.