What if, seconds before your laptop began stalling, you could feel the hard drive spin up under the load? Or you could tell if an electrical cord was live before you touched it? For the few people who have rare earth magnets implanted in their fingers, these are among the reported effects — a finger that feels electromagnetic fields along with the normal sense of touch.

The magnet works by moving very slightly, or with a noticeable oscillation, in response to EM fields. This stimulates the somatosensory receptors in the fingertip, the same nerves that are responsible for perceiving pressure, temperature and pain. Huffman and other recipients found they could locate electric stovetops and motors, and pick out live electrical cables. Appliance cords in the United States give off a 60-Hz field, a sensation with which Huffman has become intimately familiar. “It is a light, rapid buzz,” he says.

The author had a magnetic implant put in his own finger:

I would circle my finger with a strong magnet and feel the one in my finger spin. In time, bits of my laptop became familiar as tingles and buzzes. Every so often I would pass near something and get an unexpected vibration. Live phone pairs on the sides of houses sometimes startled me.

New sensory modes using low cost, low tech methods—why not? Show me a few hundred people who like their magnetic implants and I’d probably do it too.

Since the controller already contains five channels of acceleration sensing, it is simple to link this to virtual physical dynamics consistent with real-life gravity and user interaction. The acceleration signal is integrated to approximate velocity, and the resulting signal is used to control the frequency of a periodic signal mimicking the rolling of a ball of a set circumference. By varying the scaling of acceleration data and the scaling of velocity data, the mass and circumference of the virtual ball may be altered. Performing waveshaping of the final signal (or altering the stored waveform if look-up tables are used) alters the perception of the interaction between the virtual ball and the inside of the tube, creating the impression that the motion is smooth or bumpy, or that the inside of the pipe is ribbed. Integrating a second time approximates the position of the ball; this data is used to stop the virtual motion and set the velocity back to zero when the ball reaches the end of the modeled pipe…

Even lacking appropriate amplification and using somewhat un-physical coefficients, people trying the demonstration were convinced by the model – some would not believe that there was actually nothing rolling inside. Observation of users showed that their gaze would often follow the apparent position of the virtual ball, and perception of mass distribution would change depending on which end of the controller “contained” the virtual ball.

The altered perception of mass distribution shows that vibrotaction can give rise to illusions of force. I think there’s a lot of potential for this concept to be exploited for PxD.

In terms of vibrotactility, the performance space was excellent because the floor was entirely wooden and hollow. Almost all the instruments in the band could be felt as well as heard. Unfortunately the tabla and keyboard were only audible, but the rest of the instruments could be felt. The upright bass (amplified), saxophone, and individual components of the drum kit seemed to be differentiable. I felt the upright bass and lower sax frequencies in the chair I was sitting in and throughout my whole body as a mostly-constant background presence. Additionally, the snare drum felt like a distinct punch in my chest and hands. But the most distinct vibrotactile sensations came from the toms, which, in different combinations, would light up separate regions of the soles of my feet. For instance, one would be felt in my heel, another in the area just behind my toes, another in the instep. To put it dryly, tom fills were mapped to spatiotemporal patterns of vibrotactile sensation in my feet. It was really fun.