Quadric analysis for AT-cut quartz resonator humidity sensors

A new precision quadric model was proposed for the frequency equation of AT-cut resonator humidity sensors by taking reciprocal action among surface roughness, relative humidity and temperature into account, and by comparing the adsorption water molecule amounts derived from the B.E.T. adsorption equation with experimental results. Including the B.E.T. adsorption equation in the closed interval of zero to 0.5 for relative humidity, our theory agreed with experimental results.