MERMAID is a compact instrument that uses magnetoelastic resonance (MER) sensors to analyze liquid and thin-film properties. Dynamic events, such as viscosity change, phase transitions and bio-film growth can be analyzed. The MER sensor can measure properties of a coating on the surface and 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 testing and development.
The innovative excitation- and detection-coil design allows the instrument to be very compact, so the MERMAID is portable and easy to handle. The measurement is done by placing the MER sensor on top of the instrument, and no additional components are required. The wireless detection of the sensor allows the sensor to be placed a few centimeters away from the MERMAID instrument, which enables the sensor to be placed 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 andare made of a low-cost material, so they can be discarded after use.
The viscosity and the hardening and curing process of a substance can be monitored in real time using an MER sensor. The magnetoelastic film can be coated with a thin layer of the substance or immersed in a fluid. 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 for 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 and, long curing process of the nail varnish is also reflected in the data. The thicknesses of the applied paints were in the range from 50 to 150 µm.