Use of poly(2-acrylamido-2-methylpropane sulfonate) modified with tetraethyl orthosilicate as sensing material for measurement of humidity

A resistive-type humidity sensor was fabricated by thick film method using the poly(2acrylamido-2-methylpropane sulfonate) (poly-AMPS) modified with tetraethyl orthosilicate (TEOS) as the sensing material without protective film or complicated chemical procedures. Parameters that may affect the humidity sensing of material, such as the effect of adding triethylamine (TEA) or diethylamine (DEA), the dosage of TEOS on the capacity resistance to high humidity atmosphere, and the thickness of film were investigates. The characteristics of humidity sensor, such as response time, response linearity, working range, hysteresis, effect of temperature and long-term stability were further studied. The humidity sensor has less hysteresis (<2%), good linearity (R^2=0.9989) at the humidity working range of 30-90% RH, long-term stability (at least 31 days) and satisfactory resistance to high humidity atmosphere (95% RH) using the addition of TEOS (16.25%, w/w) and TEA (0.4ml) into poly-AMPS as the sensing material.