If you're paying attention, there can be an awful lot of information encoded in a series of nose sniffs. In and out, long and short, strong and shallow. One sniff, two sniffs, three sniffs. Now engineers at the Weizmann Institute in Israel have capitalized on that variety of sniffs and created a device that lets severely disabled individuals use their noses to communicate through a computer and steer a wheelchair. (Their study appears this week in PNAS.)
Sniffing is controlled by the soft palate, that bit of tissue at the back of the roof of your mouth. It's the part that closes off the nasal passages when you swallow. The Weizmann researchers theorized that people who could no longer control their bodies—quadriplegics and those with "locked-in syndrome" who are completely paralyzed—could still control their soft palate and their patterns of sniffing. The scientists created a device that measures nasal pressure and then translates that pressure into an electrical signal.
Healthy volunteers were able to use the device to play a computer game; their responses were only a bit slower than using a mouse or joystick. When the device was connected to text-writing software, several locked-in patients were able to write messages using the new device. One woman who had become locked in following a stroke seven months earlier was finally able to communicate with her family again. Her stroke had left her without the ability to even control her eye blinks, often a method of communication for patients of her type. A man who had been locked in for 18 years following a car accident was able to write his name after only 20 minutes of first trying out the device; he had given up on past attempts to use an eye tracker and found the new device "more comfortable and more easy to use," he wrote.
When the device was hooked up to a wheelchair, quadriplegics were able to learn how to use it quickly enough that they could navigate a complicated maze with only 15 minutes of practice. Commands were given in sets of sniffs—two in or two out, for instance, to go forward or backward—to avoid having an accidental breath send someone out of control.
There are, of course, limitations to the device. Writing through sniffing is incredibly slow—only a few letters per minute—but that's about the same rate at which locked-in Jean-Dominique Bauby wrote The Diving Bell and the Butterfly using eye movements. And not everyone may be able to control their soft palate; about 25 percent of healthy volunteers in an fMRI study did not have that control. But sniff control may soon become another technology to add to the toolbox for the severely disabled, letting more of them do things, like communicate with loved ones, that the rest of us take for granted.