Capacitive Humidity Sensor

Capacitive humidity sensor directly sensing the relative humidity changes , the humidity changes into a change in capacitance , and then change in capacitance by the signal conditioning circuit is converted to a standard electrical signal supplied to the associated control or monitoring circuits. Capacitive humidity sensor features are: fast response, high linearity , low hysteresis and long-term stability and good , so applications are increasingly widespread . Capacitive relative humidity sensor usually consists of thermosetting polymers , three capacitor structure , platinum electrodes , as well as integrated signal conditioning circuit ( except for high-temperature applications ) and other components. As shown below, wherein the thermosetting polymer is the outermost layer of the sensor package is mainly for protection against dirt , dust, oil and other Mian override or enter into Camshaft Position Sensor , corrosion platinum electrode , affect the sensor response speed . The outer layer of the platinum electrode is filled with holes, make sure the air with water vapor quickly and smoothly into the internal sensor , speed sensor response speed and reduce the measured hysteresis. In practice , based on the affinity of vapor capacitive, resistive or conductive thin film as a humidity sensor is sensitive to humidity , but also on the temperature-sensitive , so in order to achieve accurate measurement , or wide temperature range , temperature compensation is not necessary small. To achieve temperature compensation, temperature measurements must be placed as close to the Shaft Position Sensor measurement environment, particularly humidity and temperature is calculated using the dew point , which is particularly important. Industrial humidity and dew point measuring apparatus is usually integrated in the sensor substrate opposite a 1000 ohm platinum RTD temperature sensor for temperature compensation. When the sensor sensing area surface temperature is below ambient dew point temperature , then the sensor sensing area surface condensation is easy , even if the surface temperature or sensor sensing area within the local temperature only briefly below ambient dew point temperature, the sensor has an internal or surface condensation may form , especially when the working environment humidity above 95 %, the temperature of the subtle fluctuations are likely to cause condensation . In order to avoid humidity and dew condensation on Crankshaft Positioning Sensor influence , there is usually some measures such as maintaining good air circulation to reduce temperature fluctuations ; add to the humidity sensor sintered stainless steel filter , a waterproof coating to further suppress the condensation of .