The first participant was able to "write" at a rate of three letters per minute and the second at 1.5 letters per minute, the researchers said.
And although this might seem slow, the researchers pointed out that Jean-Dominique Bauby wrote the memoir The Diving Bell and the Butterfly using only blinks of his left eye to sort out letters. This worked out to about one word every 2 minutes. Bauby was locked in as the result of a stroke suffered during his 40s.
The device also enabled quadriplegic individuals to write and even to navigate the Internet and write e-mails.
Sniffing also equaled mobility for many participants in the trial. Both healthy controls and disabled people were able to navigate a 115-foot path, including several turns, using a series of simple commands: forward was two sniffs in; backward was two sniffs out; left was sniffs out then in; and right was sniffs in then out.
Often, it took only 15 minutes of practice to "drive" successfully.
The researchers believe that most people can breathe independently of sniffing, ruling out the possibility that an accidental breath might activate the wheelchair commands and cause a disaster.
But, even so, the device can be programmed with "safety breaks," for instance, adding extra commands so as to minimize the possibility that the wheelchair would be activated accidentally. It's just that such controls would slow things down.
The authors are now planning to test the sniff controller in other types of patients, including those in a vegetative state.
The Weizmann Institute in Israel, which conducted the trial, has applied for a patent on the technology.
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