Researchers in Japan are working on a device to help the visually impaired feel their way around a room without using their hands. The prototype device, called a Forehead Retinal System (FRS), was on display this week at the SIGGRAPH conference in Boston.
Designed by researchers at the University of Tokyo and a Japanese firm, EyePlusPlus, the system converts visual information into tactile sensations using a small camera and 512 electrodes mounted on the forehead. The camera is implanted in a pair of sunglasses, and the electrodes are placed inside a headband.
The first prototype was deployed in October 2005 and distributed to visually impaired students in Japan. At first, the students were not receptive to the new device, says research associate Hiroyuki Kajimoto of Professor Susumu Tachi’s Laboratory at the university, because they could not withstand the pain of the electrical pulses on their foreheads. Skin on the forehead lacks the thick sublayer, called the status corneum, that’s present in finger skin. Without that extra layer, the electrodes can cause excessive nerve stimulation and severe pain when activated.
In order to combat this problem, Kajimoto’s team implanted an ionic gel sheet between the electrode and forehead, which had the same thickness and electrical impedance as the status corneum layer of the epidermis.
To ensure that the device was lightweight and portable, Kajimoto’s team used the same high-voltage switching integrated-circuit used to drive micromachines. The circuit box, which is about the size of an old Sony Walkman, can be carried by the user in a small pouch and the pressure of the pulses can be controlled by a “volume” dial.
Kajimoto expects that if people have appropriate training, the device could be a surgery-free alternative to an artificial retina. According to Norman Radtke, a physician at the Retina Vitreous Resource Center in Louisville, KY, surgical retinal transplantation is 5 to 10 years away from being available to the general population. More than 700 people in the United States have retinal pigmentosa, a group of inherited eye diseases that affect the retina, and 1.7 million suffer visual impairments from age-related macular degeneration.
So this current Japanese project has enormous implications. Yet there are remaining technical challenges. Kajimoto identified two problems they’re presently working on: imaging and distance. “Currently, the project is too simple for daily life,” he says. “FRS cannot understand complicated shapes. We need to find a way to simplify objects without symbolizing the system.”
The system also currently has no depth perception. It can detect objects roughly 20 feet away, but the stimulation does not change as the user gets closer or further away from the object. Kajimoto’s team is working on measuring distance by building a stereoscopic system using two or three cameras.
While at SIGGRAPH, I had the opportunity to test the FRS in two different ways. First, I sat facing a wall to make sure no other objects were in view. Then two sticks were waved in front of the camera. I could literally feel the sticks on my forehead; as they moved or changed directions, the feeling on my forehead changed. The sensation was vibratory, as if my forehead was receiving a massage, and while slightly uncomfortable, it was not painful.
The second test involved walking. The researchers eliminated other perceptual distractions, or “noises,” in the room by blocking off a section, and they replaced the standard camera in the first test with an infrared one. Then I closed my eyes and walked around the small room, trying to avoid two poles. Although I wobbled around a bit, and occasionally stuck out my arm for guidance, I managed not to bump into anything.
“As you can see, distance is a key element in making FRS a usable device, but even more crucial is training,” says Kajimoto. He believes those with visual impairments might have an easier time with the device than sighted individuals like me. “The blind have a much more acute sense of touch and therefore are able to more quickly detect objects of different shapes, he says.” Currently, users in Japan are being trained with objects of different shapes.
Kajimoto believes the FRS will be commercially available within a year. And in 2008 he hopes to have a blind marathon runner wear an FRS in the Beijing Paralympic Games. – By Brittany Sauser
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