HYDROGEN GAS-DETECTION VIA PHOTOTHERMAL DEFLECTION MEASUREMENT

A study of a thermal wave hydrogen sensor interrogated via transverse optical beam deflection spectroscopy is presented. The sensor is a thi n film polyvinylidene fluoride film coated with a thin palladium layer . The sensitivity to hydrogen results from thermal boundary condition changes at the gas-film interface and depends upon the thermophysical properties of the gas. A simple one-dimensional model is developed to qualitatively and semi-quantitatively describe the experimental result s and it shows good agreement with the experiment. Concentrations of 0 .1% hydrogen in the presence of a balanced air mixture and at room tem perature were measured for this sensor and they indicate possible sens itivities approaching 100 ppm. (C) 1997 American Institute of Physics.