Conventional windspeed measurement systems are typically based on mechanical anemometers or ultrasonic devices. While anemometers provide a low-cost solution, their moving parts are prone to wear, contamination, and corrosion, which lead to long-term drift and unreliable operation in outdoor environments. Ultrasonic technologies offer higher robustness but come at a significantly higher cost and require more complex signal processing and power management. A differential pressure–based approach, leveraging the Venturi effect to relate static and dynamic pressure differences to air velocity, represents a solid-state, compact, and energy-efficient alternative.
Principle of operation based on the Venturi effect
When air passes through a constricted region, its velocity increases and static pressure decreases, as described by Bernoulli’s and Venturi’s principles. The resulting pressure differential, Δp, between the stagnation region and the throat of the constriction, scales with the square of the airflow velocity according to Δp = ½ ρ (v₁² − v₂²), where ρ denotes the air density. Measuring this differential pressure therefore provides a direct and physically grounded estimation of windspeed. Unlike traditional flow channels, the geometry can be realized in two dimensions as a planar or disk-shaped “Venturi” structure, allowing open-air measurement without enclosed ducts.
Sensor technology and measurement principle
The differential pressure is detected by Sensirion’s SDP3x series, which employs the CMOSens™ thermal flow sensing principle. This technology measures very small pressure differences through thermal conductivity effects in a microchannel and converts them into a digital, temperature-compensated output. The absence of any mechanical components ensures long-term stability, while the high thermal sensitivity allows detection of minute pressure variations, enabling windspeed measurements down to 0.2 m/s. The digital calibration and zero-point stability of the sensor simplify integration and eliminate the need for periodic recalibration.
System setup and mechanical integration
In a typical setup, the sensor is connected to two pressure ports placed across the Venturi constriction, for instance between the stagnation and throat regions. The measured Δp is continuously converted into a windspeed value using a calibration curve derived from computational fluid dynamics or wind tunnel characterization. The compact geometry can be injection-molded from plastic, which allows easy mechanical integration on building façades, sensor nodes, or embedded environmental modules. Due to the low mass flow through the sensing ports, the system shows strong resistance to contamination, and optional low-cost filter rings can be added to improve protection against dust and insects.
Environmental compensation and system performance
Temperature and ambient pressure compensation can further enhance accuracy under varying environmental conditions. The SDP3x sensor operates with minimal power consumption and communicates via a digital I²C interface, making it suitable for low-power embedded systems. This concept enables a cost-efficient and mechanically robust windspeed sensor that provides stable and precise measurements without moving parts. By combining multiple differential pressure sensors, directional wind components can also be derived, extending the approach to two-dimensional wind vector measurements.
Scalable solution for next-generation applications
This differential pressure–based principle, together with our proven CMOSens™ technology, therefore provides a scalable and reliable foundation for next-generation windspeed metering solutions in environmental monitoring, smart building control, and industrial automation.
