Extra Sensory Perceptions: Sensing Magnetic Fields
The first known, successful implant of an extra sensory perception to detect magnetic fields the person with the new sense was near, occurred in 2005, when a small piece of neodymium, which is a rare earth metal, that forms a permanent magnet, was coated in a thin layer of silicon, and implanted into an emergency medical technician's finger.
Todd Huffman, an emergency medical technician at St. Louis University Hospital Neurology unit, worked with implant artist Steve Haworth to add the new sense to his body. He desired the ability to tell when he was near anything that gave off a strong magnetic field, which might interfere with a pacemaker or other implanted medical equipment.
The magnet senses the presence of the field, and pulls slightly towards it. This pulling disturbs the tissue of the finger, stretching it, and triggering the deformation of pacinian corpuscles all around the fingertip. With practice, it became possible to determine field strength and direction in real-time, from these pulling sensations.
The pacinian corpuscle consists of a single nerve fibre, it's sheath stripped, in the center of what could best be described as a gas bag onion. Concentric layers of webbed sheathing surround the nerve, radiating outwards like the skins of an onion. Bearing a strong resemblance to cargo netting in their basic function, these layers serve the opposite purpose. They are there to detect and amplify any change in the pressure around them. This change is then detected by the specific way the corpuscle deforms, and this is in turn, transmitted down the nerve as an electrical signal pattern.
Stretching, compressing, to the corpuscle, it is all the same. The magnets work, by being implanted behind the layer of corpuscles clustered around the fingertip. As it pulls it compresses some, drags others. Very much in the same way as dragging a pattern of metal beads behind glass, with a magnet. The corpscles shift in large numbers, to follow the magnet's movement. Unlike the beads, they settle back into place afterwards as the natural tissue elasticity pulls them back.
The fingertips are chosen precisely because of this concentration of corpuscles. Anywhere where the density is lower, this sensory interface does not work. Lips and erogenous zones would also function, but are not recommended, due to the known side effects.
The Down Side
All is not sunshine and roses, however. There have been found to be very real, and serious health risks to having magnetic senses implanted, that should give anyone pause.
For starters, even the very slight stretching and compression of living tissue that Todd experiences, if carried on over a protracted period of time, causes an effect very similar to white finger. White finger, sometimes also termed dead finger, is one of the dangers of vibration based haptic immersion over an extended period of time. It derives its name from the colour the body part initially turns on the onset of this condition. It is caused by a loss of blood flow by prolonged exposure to vibration, the same as experienced with heavy machinery, and despite the name, it can occur on any part of the body. If exposure continues past the tissue bleaching, possible side effects include that body part turning numb, an increased sensitivity to cold, and finally, necrosis ? where the tissue literally starts to die off.
With a neodymium magnet, you don't get the vibration effect, as the pull of whichever magnetic field is nearby, is steady. What you do get however, is steady compression. The problem here, is that the compressed soft tissue simply dies away. This is because the compression effect has the result of crushing the small capillaries that ferry blood to the fingertips, or other near-surface bodily areas. Without this blood supply, the end, comes quickly for those cells. Many of the same symptoms are exposed before this occurs. A problem is, the steady compression actually hastens their arrival, over a rapid vibration.
Another great problem is neodymium itself. The rare earth metal is toxic to human tissue. This is why it is coated in silicon to begin with. Should the silicone coating - which is after all, only thin - break, or tear, you wind up with the situation of a toxic element, which the immune system will identify and attack, being present within the body.
Documented cases of toxicity have been reported, although by ad large neodymium's effects on body tissue under prolonged exposure are still unknown. What we do know is that in the short term, the tissue near a compromised implant first swells up, then returns to normal, and slowly turns black in a spreading patch of necrosis. Silicone sheaths do themselves break down after a number of years, and tear easily under sheering effects.
Whilst the addition of a new sense may, and for some people, such as those with a pacemaker fitted - does prove absolutely invaluable, the risks are considerable, and at this stage in development, are utterly unrecommended.