MEMS based humidity sensor using Si cantilever beam for harsh environmental conditions

Abstract

Sensing and controlling of humidity is a major issue in various industries. Many of the equipments in industries require monitoring and controlling humidity for its efficient and reliable operation. This paper presents the design, fabrication and complete characterization of a micro cantilever based humidity sensor for harsh environmental conditions. A Si cantilever humidity sensor based on capacitive principle is designed and displacement analysis is performed on the sensor. The polyimide, acts as a sensing material for this sensor. The polyimide is coated over the beam to sense the humidity. If the humidity absorbed by the polyimide material increases, the mass of the beam is also increased. The deflection of the beam causes the change in capacitance. The relative humidity can be calculated using the change in capacitance. The beam had an appreciable deflection causing a notable change in capacitance. The variation of capacitance is in the order of picofarads. The sensor is designed in a structure that can tolerate the harsh environmental conditions like pressure, temperature, etc.