Embedded MEMS-Based Concentration Sensor for Improved Active Fuel Cell Performance

A MEMS-based methanol concentration sensor for monitoring and controlling the methanol to water ratio in a DMFC system is described. This sensor is based on a microfluidic chip that employs a resonant microtube and on-chip platinum temperature sensor to measure the density of a fluid. Using the density and temperature output the methanol concentration is determined. The performance of the sensor over temperature, concentration and in the presence of formic acid by-products is examined. Test comparisons between this sensing method and refractive index and speed-of-sound methanol concentration sensors are made. Additional biofuel applications for the sensor will be discussed.