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The Embedded Moisture Sensor (EMS) is an indirect moisture measurement device also known as a Duff Gauge, Surrogate Moisture Sensor or Wood Resistance Humidity Sensor.


The EMS sensor is used to perform an indirect measurement of moisture levels in materials not compatible with standard measurement techniques, such as gypsum, concrete, masonry and insulation. The EMS sensor uses known moisture and temperature response curves of Helmlock as a baseline and is further calibrated by correlating the electrical characteristics with gravimetric measurements. Sensors are embedded in the material to be monitored to obtain the relative moisture level of the surrounding area through capillary absorption.


Sensor readings are acquired by the WiDAQ, a precision data acquisition device, and transmitted to the Building Intelligence Gateway where sensor specific temperature compensated calibration curves are applied.


Two sensor grades are available. Commercial grade sensors use published a and b calibration values for the wood species used. Research grade sensors are individually calibrated to accurately relate gravimetric moisture content with electrical moisture content. Typical sensor elements are based on Western Hemlock, a hardwood with favourable characteristics. 


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Embedded Moisture Sensor (EMS)

    • The EMS is available in both block and plug styles. The cylindrical plug sensor is suitable for monitoring stone, concrete, and masonry, where drilling a hole to the appropriate depth is the most practical access. The block style is suitable when a cut-out at the correct location is feasible, for example, in rigid insulation and gypsum sheathing. Further details and custom sizes are available on request.
    • Sealed and rugged design allows for deployment in harsh construction environments
    • Integrated temperature sensor used for temperature compensation and for reporting temperature sensor data.
    • Research grade EMS units are individually calibrated to produce a and b calibration constants for an accurate moisture content calculation. Formulae available upon request
  • Electrical Characteristics

    Operating Voltage: 2V to 12VDC

    Resistance Measurement Range: 100Ω to 1GΩ

    Thermistor Measurement Range: -40°C to 125°C

    Thermistor Part Number: MF52C1104F4150

    NTC Thermistor Beta Value: 4150K

    BiG/Analytics Sensor Configuration: Thermistor: MF52(C). Moisture: Moisture(%)



    Operating Temperature: -40°C to 50°C

    Application Temperature: 5°C to 50°C

    Storage Temperature: -40°C to 50°C

    Storage Humidity: 30% to 70%RH




    Plug: 38mm x Φ13mm (1.5" x Φ 0.5")

    Block: 50 x 38 x 19mm (2" x 1.5" x 0.75")

    Custom sizes and configs available upon request


    Wiring: 22 AWG 4 Conductor Stranded (typical)

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