A
magnetoelastic material is a material that changes its dimensions when it
is exposed to a magnetic field. A thin ribbon of a magnetoelastic
material forms a magnetomechanical resonator and it can be viewed as 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 of the status of the sensor.
Properties of a media, such as its viscosity, density, pressure or flow
speed can be determined by analyzing the response of a magnetoelastic
film placed in the media. It is also possible to follow a dynamic event,
for instance the curing process of glue and paint. The magnetoelastic
film can be made sensitive to many physical properties by coating it with
various materials, for instance a humidity sensor can be constructed by
coating the film with a humidity absorbing material. When the humidity
sensor is placed in a humid climate, the coating will absorb water and
become heavier. Similarly, when the sensor placed in a dry climate, the
coating will release water and become lighter. A heavy sensor will
vibrate with a lower frequency than a light sensor.
Imego’s sphere of expertise in this field covers magnetism, electronics,
simulation, packaging and industrial design.
Viscosity, hardening and curing
MERMAID is a measurement instrument for analysis of liquid and thin film
properties using magnetoelastic resonance (MER) sensors. The MER sensor is
either coated by or immersed in the substance under investigation. Dynamic
events such as viscosity changes, phase transitions or 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), which uses
inexpensive sensors for wireless detection of humidity. The sensor is
passive, so there is no need for batteries or other power sources. The
WHDS can be applied to measure humidity in places that are hard to reach,
for instance behind walls, 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 the moisture uptake and release in exterior panelling paint. The
moisture uptake properties are believed to be important for the tendency
for mould 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 wirelessly measured using the
magnetoelastic resonance method. Moisture absorption and desorption
properties of different paints and thicknesses can be studied. The sensor
method make it is possible to classify paints and to study 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, for instance paint or finish. The
thickness of the coating on a magnetoelastic film will give a
corresponding shift in the resonance frequency.