Electromagnets are the classical way to generate intense magnetic fields. If you apply the electrical current across a coil, the magnetic field is quite small. But if you wrap the coils around an iron yoke, you can generate much stronger magnetic fields. Unfortunately, if you need to scale up a magnetic separation process, you also need to increase the electrical power to the magnetic separation rack and the amount of iron and copper used for the coil.
This post is about biomagnetic separation with a magnetic separation rack, and how to scale-up this process. If you are interested in this topic, download our free ebook The Basic Guide to Scale-up Biomagnetic Separation Processes:
What happens when we use bigger magnets?
The heat generated by the resistance of the larger coils will be significantly greater as you scale up and will require a substantial electromagnet cooling system. Theoretically, you can adjust the values of the magnetic fields or change the field profiles that generate the magnetic force in biomagnetic separation devices. However, once you produce large lots you will need to accurately control the electromagnet adjustable parameters (electrical current, pole pieces, system temperature).
In production facilities you will need to ensure you are always using exactly the magnetic separation conditions you have already validated. Therefore, when you scale up a magnetic separation system that uses an electromagnet, you must consider the additional cost of the following:
- Much larger electric bill
- Power supply maintenance (for a power supply compliant with the Electromagnetic compatibility of your lab)
- Larger floor space
- A refrigeration infrastructure able to flow enough water to control the temperature of your device
- Maintenance of used coils, isolations, electronics and yoke.
MRIs typically use superconducting coils to avoid many of the above problems. However, for a system similar to an MRI, you will need to cryogenically cool the coils, making this technology far too expensive for a biomagnetic separation device.
Rare Earth Permanent Magnets, the perfect solution
A better alternative to electromagnets is the use of Rare Earth Permanent Magnets to generate the required magnetic field profile. Homogeneous biomagnetic separation systems can utilize these Rare Earth Magnets because the parameters of the separation process in these devices can be well defined (e.g. the optimal magnetic force and the field profile necessary to magnetically saturate the beads).
With Rare Earth Permanent Magnets, conditions comparable to those using Electromagnets can be achieved with less weight, no need for cooling systems, no electrical power, no power supply and no maintenance costs. If the device is used at temperatures less than 80ºC, conditions will remain constant for decades.
Therefore, Rare Earth Permanent Magnets provide a solution that gives you long term stability, a small footprint, and a one-time upfront cost for the system itself with no maintenance fees. Compared with Electromagnets, Rare Earth Permanent Magnets are a much more cost effective and reliable way to power biomagnetic separation devices.
Don't forget to check these posts from our blog in order to get a deeper insight into the scaling-up of biomagnetic separation processes:
- Keeping lot to lot consistency when using biomagnetic separation at different volumes
- The secret to avoid magnetic bead (and biomolecule) separation losses when scaling up
- Scaling Biomagnetic Separation Process avoiding irreversible aggregation problems