Economical and precise series of small MEMS humidity sensor capacitors

Würth Elektronik is launching a very compact, cost-effective digital humidity sensor in the WSEN-HIDS series. The MEMS sensor measures with a precision of ±1.8% RH in the 20-80% relative humidity range. The DFN package for SMT assembly measures just 1.5mm x 1.5mm x 0.5mm. The sensor works with a current of only 0.4µA and can be operated with a power supply between 1.08V and 3.6V. So, it is ideal for distributed IoT sensor networks, such as those in smart farming applications.

This humidity sensor uses a dielectric polymer that interacts with water molecules to adjust the permeability of the capacitor structure depending on the relative humidity of the surroundings. A temperature sensor is also included. Using the integrated ADC, the momentary temperature and humidity information can be transmitted as 16-bit measurement data directly to conventional microcontrollers via an I²C interface. The heater (also included) with three selectable heating levels can be switched on temporarily as needed, so the sensor works effectively even under demanding ambient conditions, and the measurement is not falsified by condensation.

The humidity sensor is extremely versatile – from air conditioning equipment to data loggers in the food industry to smart buildings, vertical farming, and other applications that require precise environmental control. The sensor is part of the FeatherWing sensor and the IoT Development Kit from the company to support rapid prototyping.