Macrotyloma uniflorum proteins as humidity sensing material

For the first time, proteins extracted from a plant source have been used as a humidity sensing material for the development of a humidity sensor. Humidity sensing characteristics of protein composite extracted from the seeds of Macrotyloma uniflorum coated on ceramic rod having built in electrodes were investigated for their electrical behavior as a function of relative humidity. The resistance versus % RH was measured for multiple layers of protein (each layer of 10 µl). Resistance increases slowly with decreasing humidity up to 30%RH followed by drastic increase at the lower range of RH. Humidity sensing range was found to increase with increasing the number of layers of protein, thus with increasing thickness of the coat. Humidity response of the sensor having four layers was found to cover a wide range of (8% to 86%) relative humidity. A five order increase in resistance was observed for change in relative humidity from 86% to 8%RH. The sensor response and recovery time is about 50–60 s and 160 s respectively. The material is characterized by FTIR.