Studies have shown that with the right amount of white noise in the background, peoples' sight, hearing, balance control and sense of touch improve. Utilizing stochastic resonance, which is the principle at work in white noise, researchers at the Georgia Institute of Technology have discovered that the sense of touch can also be improved by applying vibrations to a person's finger. They have been testing a glove that incorporates a prototype fingertip-buzzing device, that could ultimately lead to products worn by people with nerve damage, or whose jobs require exceptional manual dexterity.
The device contains an actuator, that is attached to the side of the fingertip - the bottom of the finger is exposed, so its skin can come into contact with surfaces. That actuator generates high-frequency vibrations, the intensity of which can be varied. A group of ten volunteers had the device attached to their non-dominant index fingertip, and told the researchers at what level of intensity they could actually begin to feel the vibrations - that point was called their "vibration amplitude threshold."
In subsequent tests, the volunteers had to perform a variety of tasks, with the actuator vibrating at anywhere from 0 to 150 percent of each individual's threshold.
One test required them to distinguish between one and two points pressing on their fingertip. In that case, it was found that vibrations between 75 and 100 percent of their threshold produced the best performance. In another test, where they had to state whether or not they could feel different weights of filaments touching their fingertip, they could feel lighter filaments as the vibrations approached their threshold.
A fourth test involved them feeling one piece of sandpaper, then trying to determine which of nine other pieces had the same grit. At vibration levels of 50 and 100 percent of their threshold, a 15 percent improvement in performance was noted. The fourth test required them to hold an object as lightly as possible, without dropping it. The subjects did best at levels of 50, 100 and 125 percent of threshold.
The Georgia Tech researchers are now working on fine-tuning the optimal amplitude and frequency of the vibrations, and looking into the possibility of applying actuators to both sides of the fingertip, or to the fingernail. They are also trying to determine the possible long-term effects of using the device.
