A magnetoelastic material changes its dimensions when it is exposed to a magnetic field. A thin ribbon of a magnetoelastic material forms a magnetomechanical resonator like a small tuning fork. Exposing the film to a short magnetic pulse excites the film, and it starts to oscillate. The frequency, amplitude and damping of the vibration give information about the status of the sensor.
Properties of a media, such as its viscosity, density, pressure and flow speed, can be determined by analyzing the response of a magnetoelastic film placed in it. It is also possible to follow a dynamic event, such as the curing process of glue and paint. The magnetoelastic film can be sensitived to many physical properties by coating it with various materials. For example, a humidity sensor can be constructed by coating the film with a humidity-absorbing material. When the humidity sensor is placed in a humid environment, the coating will absorb water and become heavier. Similarly, when the sensor is placed in a dry environment, the coating will release water and become lighter. A heavy sensor will vibrate with a lower frequency than a light sensor.
Imego’s expertise in this field covers magnetism, electronics, simulation, packaging, and industrial design.
Viscosity, hardening and curing
MERMAID is an instrument for the analysis of liquid and thin-film properties. Using magnetoelastic resonance (MER) sensors, the sensor is either coated by, or immersed in, the substance under investigation. Dynamic events such as viscosity changes, phase transitions and bio film growth on the surface of the MER sensor can be analyzed. The MERMAID is useful in many applications, such as food processing, biomedicine and polymer testing.
Read more about MERMAID
Humidity detection
We have developed a Wireless Humidity Detection System (WHDS) that uses inexpensive sensors to detect humidity. The sensor is passive, so batteries or other power sources are not needed. The WHDS can be applied for measure humidity in places that are hard to reach such as behind walls and in closed packages and for monitoring moisture in food, pulp and sand.
Read more about the Wireless Humidity Detection System
Moisture uptake in paint
We have built an experimental setup for investigating the time dependence of moisture uptake and release in exterior paneling paint. The moisture uptake properties are believed to be important for the tendency for mold growth on a painted surface. In our setup, the paints under investigation are coated on a magnetoelastic film, and the mass increase due to the moisture uptake of the paint is measured wirelessly using the magnetoelastic resonance method. Moisture absorption and desorption properties of different paints and thicknesses can be studied. The sensor method makes it is possible to classify paints in function of their moisture absorption and desorption properties.
Coating thickness
The magnetoelastic sensor can be used to make a sensitive non-contact thickness determination of a coating likepaint or other finishin material. Variations in the thickness of the coating on a magnetoelastic film will shift the resonance frequency.