A Low-Cost Capacitive Relative Humidity Sensor for Food Moisture Monitoring Application

Bo WANG1,  Man Kay LAW2,  AMINE Bermak1
1HKUST, 2Macao University


In this paper, a low-cost capacitive relative humidity (RH) hygeometer for food moisture monitoring is presented. The variation of dielectric constant of polyimide (kapton) film to relative humidity enables the sensor’s functionality. A fully differential capacitance to digital converter (CDC) is utilized as the hygometer readout module, which makes the humidity sensor immune to circuit wiring parasitic and enable its long-term stability. The sensor is implemented using TSMC1P6M 0.18m technology with post micromachining for kapton film coating. Simulation results indicate that an accuracy of +/8%RH can be achieved sensing from 10%RH to 90%RH, with 5.4W power consumption for sensing and 21.6mW power consumption for sensor heating .