Fabrication and characterization of innovative gas flow sensor

A hot-wire type flow sensor, as one arm of Wheatstone's bridge, is proposed using gold plated tungsten wire with innovative base material (soft ferrite) and geometry to enhance the mechanical stability and lifetime. The bridge excitation current is varied from 100 to 210 mA and the performance is tested using air as a flow gas. The flow sensor is calibrated for hydrogen (H2) and carbon dioxide (CO2). King's formula, which is comprehensively used in hot-wire anemometry, is verified for both the gases. The gas having higher thermal conductivity and lower molecular weight gives better response. This sensor can be used as flow gas analyzer. Response time of the sensor for this base material is few seconds. The repeatability and accuracy of the sensor is within ±1 and ±2% of full range (1-14 lpm), respectively.