See Product Details

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 liquids (for instance ferrofluids), powders or solid samples. It creates a "magnetic fingerprint" of the material making it useful for a wide variety of different applications, ranging from measurements on magnetic particle systems, geologic soil analyses to medical diagnostics.

The DynoMag system

The DynoMag system is a portable AC susceptometer 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. Induction technique is used in order to detect the AC susceptibility. The magnetic flux change due to the sample is detected with a well balanced detection coil system. The detection coil system is centered in an excitation coil system connected to an AC-source 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 DynoMag calibration procedure is one of the key features that ensures the large frequency range and high resolution in magnetic moment.

The system software governs the whole experimental set up (for instance time constant setting, lower and upper field 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 comprising single-domain crystals with slow internal relaxations we are also able to determine the size distribution of the particles.

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 magnetic AC susceptibility.

AC susceptometry 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 size (when the particle includes thermally blocked single domains). This makes AC susceptometry a very good parameter in order to have a good control of the manufacturing process of magnetic particle system.

AC susceptometry 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.