MERMAID is a unique measurement instrument for analysis of liquid and thin film properties using magnetoelastic resonance (MER) sensors. Dynamic events such as viscosity change, phase transitions or bio film growth can be analyzed. The MER sensor can measure properties of either a coating on top of the surface or of the medium surrounding the sensor. MER sensors together with the MERMAID instrument are useful in many applications, such as food processing, biomedicine and polymer test and development.
The innovative excitation and detection coil design allows the instrument to be very compact, allowing the MERMAID to be portable and easy to handle. The measurement is done by placing the MER sensor on top of the instrument, no additional components are required. The wireless detection of the sensor allows the sensor to be placed at a few centimeters distance from the MERMAID instrument, allowing the sensor to be for instance in a test chamber without any wires attached. The sensor can be read out through all non-metallic materials. The sensors are robust and easy to handle. In addition, the sensors are made of a low cost material, meaning that the sensors can be disposed after use at a low cost.
The viscosity and the hardening and curing process of a substance can be monitored in real time using a MER sensor. The magnetoelastic film can either be coated by a thin layer of the substance or (for a fluid) immersed in the substance. The properties of the substance are monitored by measuring the resonance frequency, the amplitude and the damping of the MER sensor. With this method we can for instance follow a time dependent solidification process in real time and in great detail. We are currently evaluating the use of MER sensors in an application aimed towards the food and polymer industry.
The measurement example shows the drying process of thin layers of nail varnish applied on the surface of a MER sensor. The nail varnish goes from viscous to elastic during the drying, which is reflected in the measurement. The slow long term curing process of the nail varnish is also seen in the data. The thicknesses of the applied paints were in range from 50 to 150 µm.