Würth Elektronik WSEN-HIDS humidity sensor

Würth Elektronik has developed a microelectromechanical system (MEMS) sensor measuring 2 x 2 x 0.9 mm in size. Due to its low energy requirements and its calibrated and temperature-compensated digital output, the sensor measures humidity and temperature with long-term stability.

The WSEN-HIDS humidity sensor is based on advanced MEMS technology: a dielectric polymer absorbs or releases water molecules in proportion to the relative humidity in the surroundings, thereby changing the permeability of a capacitor structure. The humidity sensor with integrated analog-digital converter and temperature sensor can be connected to commonly used microcontrollers via an I²C or SPI interface. The company’s software development kit makes it quick and easy to individually set data rates and use the interrupt pin.

The MEMS sensor delivers calibrated measurement results with accuracy of ±3.5% RH in the 20–80% RH humidity range, with outputs at a data rate in the millisecond range. Condensate forming on the surface of the polymer structure can be removed by activating a built-in heater, so the sensor can generate measured data again within a short time. The operating temperature range is -40 to +120°C.

The sensor promotes rapid terminal device development because developers can use a digital output directly via I²C or SPI and do not have to worry about calibration or temperature compensation. The sensor’s interrupt pin can also be used to wake up the microcontroller if the humidity changes. This is suitable for economical and low-maintenance monitoring functions.

The current consumption of the humidity sensor is 8.9 µA in continuous operation, with measurement data available every second. Using a CR2032 button cell with 230 mAh capacity, this corresponds to a battery life of about three years. If the sampling rate is reduced, applications stay maintenance-free even longer.

Alongside classical applications, such as heating, ventilation, air conditioning, building automation and cooling systems, the humidity sensor is also suitable for data loggers, as well as stationary and portable IoT applications. For modern applications, Würth Elektronik provides developers with an evaluation board.