feeling a magnetic field

Kewl. I'm going to inject myself with ferrofluid!

Cheers

On Mar 9, 2018, John Larkin wrote (in article):

Yes. I felt it as a twitching in my leg when I was being scanned by a Siemens

Tim, If plant Health and Safety at Really Big Med, inc was briefing very skilled people not involved in the project to stay away from the monster prototype with "light headedness and involuntary muscle action", there is something to it.

Steve

not necessarily.

NT

Yes. I've got a hobby as a test specimen in various research projects. The tools I've experienced are TMS, 1.5 and 3T fMRIs.

Transcranial magnetic stimulation was funny when they moved my fingers and tried to mess up my clock.

Moving your head in or close to the 3T magnet gives a disoriented feeling due to induced voltages. After almost falling off the patient bed I nowadays move my head much slower close to the magnet.

They always have to remind me not to form a loop with y hands. Apparently you can get RF burns from the excitation RF.

I experienced something similar when walking briskly past an unshielded superconducting magnet with an internal flux density of several Tesla. It was a "light headed" sensation - which was repeatable.

John

'bout 10 years ago I had a very bad case of the flu; another good reason to get a flu shot is that it's a viral infection and viral infections can do all sorts of nasty things beyond either just a) kill people who are elderly/already sick or b) you recover in a week and you're fine. It depends on your particular biology if other stuff gets affected, and also the antibodies that your own body produces in a strong immune response can sometimes "mistarget" and attack _you_ cells in addition.

My inner ear/vestibular system was affected by this one, I had vertigo/balance problems on and off for about a year (had to do physical therapy for that) in addition to lingering neuropathy/leg pain for several months, and higher levels of general anxiety/startle reflex/occasional insomnia for a couple years further.

When my vestibular system had been injured and they were going thru the battery of tests including MRI I definitely notice a severe feeling of disorientation/vertigo when the machine kicked in, it was so severe the first time when I wasn't prepared for it they had to stop the test.

Walking on next floor above, my magnet on a string moved around, felt it tugging and turning. At that point I decided it might affect equipment above. Massive shielding took place. Had to make an incubator out of plastic case and tubing. Interesting project.

Greg

I was part of a trial for this.

Each pulse felt like someone tapped your scalp sharply with their finger. It felt like the muscle under the scalp momentarily contracted.

A slight head ache after each round of treatment but that may have been down to the stress.

As part of setting up the level of field to apply they pointed the coils toward a particular point in the brain and increased the power until my hand muscle flinched. I can't recall which hand, it was maybe 10 years back.

It supposedly worked well for some participants.

Optics (and mounts) can be interesting near big field gradients. If well aligned, it's not so bad, but if the beam is near some edge..

George H.

This would seem to be a very minor effect - unless you are a "magnetic armband" salesman, in which case it will promote well-being, improve your immune system, and generally make you want to buy magnetic show insoles and a magnetic bed too.

Red blood cells are approximately frisbee shaped, and very flexible. Capillaries have an approximately circular cross section. Any capillary wide enough to let a blood cell through in one orientation will let it through in any orientation. Indeed, part of the whole point of the system is that red blood cells have to squeeze through the capillaries - this is when they swap gasses with the rest of the cells.

It may be that very strong magnetic fields have some effect on red blood cell orientation. It may be that this can have a small but measurable health effect over the long term. But that's a very long way from being able to feel a magnetic field.

The confinement, the noise, and the whole experience of an MRI will have a disorienting effect. That will be a very real effect, even if it is "all in your head". My guess - without having seen any studies on the matter - is that you would feel much the same in a "placebo" MRI with the magnetic field turned off.

Of course you could feel magnetic fields if you put a magnet in your finger!

I tried a magnet on cats head. Not sure. Need further testing.

Greg

One project I worked on measured the rotation of polarization on a red lase r passing thru a diluted blood sample. This is used to measure the waste ma terials from malaria parasites. The parasite breaks down hemoglobin and its waste products are rich in iron compounds. Rotation of three to six Tesla Halbach arrays works great for a standard 10 mm optical cuvette.

We could see the presence of the parasite starting three to four weeks be fore the standard microscopy test.

Normal blood cells. (Diluted solution so as to freely transmit the light) would show a slight polarization shift in the instrument. Infected blood wa s at minimum two orders of magnitude higher. Normal blood rotating as th e sample would easily show up on a lock_in amplifier, parasitemia could eas ily be seen with just a 12 bit ADC and a reverse biased photodiode with a f raction of a milliwatt of laser light.

So it is very plausible that an undiluted sample of blood tightly confined would cause some tiny effect that can be sensed.

Steve.