From National Geographic:
People who are paralyzed from the neck down might soon be leading themselves around by the nose—literally. A new electric wheelchair allows the severely disabled to guide their movements by sniffing into tubes.
Sniffing depends on highly coordinated motions of the back of the roof of the mouth, aka the soft palate. This region receives signals from several nerves that are often unaffected by paralytic injuries and disorders.
That means some patients with disabilities ranging from quadriplegia to “locked-in syndrome”—where a person is completely paralyzed, save for eyeblinks—retain the ability to sniff with precision.
Based on this idea, scientists with the Weizmann Institute of Science in Rehovot, Israel, devised a new sniff controller, which uses tubes placed up the nose to measure sniff-triggered changes in nasal air pressure.
Related: Brain-controlled wheelchair
Earplug provides steer-by-tongue control (by detecting changes in ear pressure)
Steering a wheelchair with tongue movements (and a magnet on the tongue)