What are the Types of Micro Coils Available in Market?

There are numerous objects which a device in the medical or industrial sector requires for performing their daily tasks. Each of these devices has one common aspect which is commonly known as micro coils.

The coils might have different properties which help in improving the function of a device. Primarily there are three distinct types of these coils which are used in such devices. Through this article, you will come to know of all the three types.


Have a look below!

  1. Planar coils

This happens to be the standard geometry used object. Its design is based on a spiral structure which has a contacted centre winding towards outside by utilizing another layer’s connection. This layer type is isolated electrically with a layer of thin oxide. So, according to this configuration, the radiofrequency coil’s axis should be perpendicularly oriented to its static field of external portion.

  1. Solenoid coils

This is classical geometry for generating magnetic fields with the help of electrical current. Though this one has a limited number of windings, it will provide a homogeneous field. Moreover, it also has an excellent filling factor, which is quite possible if an individual winds this coil directly onto any holder, which consists of a sample.

Miniaturization is done to scale several hundred µm (micrometres) which is not much difficult, but this wire’s diameter, which ranges between 20-50 µm, becomes quite small. Also, one should know that a freestanding coil is a delicate object.

Reducing this below the diameter of 100 µm is technically possible, but handling and machining such coils becomes a rather tedious task. Hence, this is why various other technologies for microsystem fabrication such as LIGA, bulk micromachining, and moulding through micro-injection technique are applied.

For solenoid micro coils addition of more turns to a coil enhances B1/i ratio along with signal response and inductance. Also, at a similar time, this coil resistance increases linearly. This improves sensitivity, which is proportional to several turns’ square root that is denoted as (n).

Also, one will have massive ohmic heating at coil’s centre along with arcing’s enhanced danger. Thus, optimum is found for just a specific limited turning number. Also, a susceptibility effect that causes static distortions is an essential aspect of micro-coil probeheads’ design.

  1. Saddle coils

This is the most intricate geometry out of these three types. Here, the B1 field is primarily generated by four segments of vertical wires. Due to this coil’s geometry, the field is more uniform within the z-direction over planar coils.

This coil is formed generally from wire; however, frequently it can also be etched from a copper foil before adhering it to PTFE tubing or glass. When etched from copper foil, it leads to a remarkable geometric precision that results in better homogeneity. Furthermore, this coil is accessible easily and offers an excellent filling factor of magnet bore’s usable portion. Hence, this is why people use this in NMR (nuclear magnetic resonance) microscopy often.

These are the three types of micro coils you will come across in a device in various sectors like the medical, industrial, etc. So, when getting products,to ensure checking the coils used for better outcomes.


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