Miniaturized electrochemical methanol sensor without gas diffusion backings

Miniaturized electrochemical sensors are assembled that monitor the concentration of methanol fuel used in direct methanol fuel cells (DMFC). Reduction in the size of the sensor unit is made possible by eliminating both the gas diffusion backings and any type of housing needed for physical integrity of the unit. The small unit can be placed at any site of the fuel supply path so that it has direct contact with the fuel through mesh-type current collector attached to catalyst-coated membrane. It is demonstrated that the sensor, with 0.15 mg of electrocatalyst loaded on each electrode of 0.25 cm2 surface area, is capable of monitoring the fuel in the concentration range from 0.5 to 3.0 M and in the temperature range from ambient one up to 80 °C, consuming electrical power as low as 1 mW.