Imego has developed a small portable instrument for dynamic magnetic analyses. It has unrivaled performance with the largest frequency range available, regardless of size and price! The instrument can analyze magnetic samples in the form of colloids, powders or solid samples. It creates a “magnetic fingerprint” of the material making it useful for a wide variety of different applications, ranging from geologic soil analyses to medical diagnostics.
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Dynamic magnetic characterization |
In order to fully optimize a system where magnetic materials are used it is of crucial importance to understand the magnetic properties of the material that is being used in the system. In order to gain this knowledge the most straightforward is to magnetically characterize the material both with static magnetic fields (that gives the equilibrium magnetic properties) as well as time dependent magnetic fields (that gives the dynamic magnetic properties). The dynamic magnetic properties give information on how fast the magnetization is building up in the material. Different types of magnetization processes, for instance magnetization reversal in magnetic singledomains (Néel relaxation), randomly rotation of particles containing thermally blocked singledomains (Brownian relaxation) or domain wall motion as in polydomain materials can be detected with dynamic magnetic measurements. All of these magnetization process creates a specific pattern in the dynamic magnetic properties for instance in the frequency dependent magnetic susceptibility.
Measuring the frequency dependent susceptibility is almost the same as a spectroscopic detection where the different relaxation processes is visualized as relaxation peaks at their specific frequencies. In a magnetic particle system the magnetic susceptibility at low magnetic fields is sensitive to the size of the magnetic single domains, the number of magnetic single domains per particle, the configuration of the magnetic single domains in the total particle, the material in the single domains, the concentration of the magnetic single domains and also on the total particle sisze (when the particle includes thermally blocked single domains). This makes the static as well as the frequency dependent susceptibility a very good parameter in order to have a good control of the manufacturing process of magnetic particle system. Measuring the frequency dependent susceptibility can be found in vast area of applications, from magnetic particle manufacturing to measuring soils in geophysical applications. In the case of detecting Brownian relaxation of particles including thermally blocked singledomains we are able from the experimental data determine the size distribution of the particles using an algorithm included in the software of the dynamic susceptibility system. With the same instrument we can also study possible clustering of the particles. With this instrument we are also available to follow the binding reactions of different substances to the surface of the particles. At Imego we are using this method in a biosensor system were we detect concentration of different kind of biomolecules in a liquid.
The Dynamic Susceptometer is a portable magnetic instrument where it is possible to measure dynamic magnetic properties of liquids, powders or solid samples. The frequency range is from 1 Hz up to 200 kHz with a resolution in magnetic moment better than 10-11 Am2 at 1 kHz. The upper and lower frequency range can be ustomized for a typical application. Induction technique is used in order to detect the dynamic magnetic properties. The magnetic flux change due to the sample is detected with a ell balanced detection coil system. The detection coil system is centered in an excitation coil system connected to an AC- ource that delivers the time dependent current to the excitation coil, that gives the excitation field. The signals from the detection coil system are fed into a low noise Lock-In amplifier.
The system software governs the whole experimental set up (for instance time constant setting, magnetic field amplitude, lower and upper filed range, number of data points etc.) and the collection of the data and presentation of the result in a user friendly interface. For the detection of magnetic particles including thermally blocked single domains we are also able to determine the size distribution of the particles. In the instrument there is also a calibration procedure that is performed in the whole frequency range from a few Hz up to 200 kHz. The used technique is schematically visualized in the figure above. |