Blink once for yes, twice for no. This technique is frequently used in movies, TV and real life to communicate with a person who is severely injured. It is also used to communicate with “spirits” and even as a secret code for perfectly healthy individuals. In either case, the communications are always limited to yes or no. With the help of pressure sensors, the ability to communicate and even control objects could improve dramatically.
In the report, “Sniffing enables communication and environmental control for the severely disabled,” researchers investigated and confirmed a premise that in addition to eye control, sniffing may remain unimpaired following a severe injury. This is of interest especially for quadriplegic and “locked-in syndrome” patients. Locked-in syndrome patients have intact cognition but are completely paralyzed, so communicating using eye blinks is a harsh reality.
For their analysis, researchers needed to measure nasal pressure and convert it into electrical signals; they needed a pressure sensor that could provide very accurate, high resolution linear measurements of low pressure signals. For their sniff controller, the researchers used All Sensors’ 1-INCH D1-4V-MINI Miniature Amplified Output pressure sensor. With this sensor, common mode errors and output offset errors due to change in temperature, stability to warm-up, stability to long time period, and position sensitivity are significantly reduced.
To confirm their theory and the possible capabilities of nasal pressure variations, measurements on healthy subjects were made using a mouse, joystick and the sniff controller. Figure 1 shows the approach, data and sensor used for the measurements. With the theory confirmed on healthy individuals, the next step was testing on the target test group.
Figure 1. Data from sniff controller measurements (a) using the 1-INCH D1-4V-MINI low pressure sensor (b) show excellent results compared to well-established mouse and joystick control techniques.
Using precise nasal pressure measurements, the researchers’ test results show that sniffing allowed completely paralyzed locked-in participants to write text and quadriplegic participants to write text and even maneuver an electric wheelchair. They also determined that the sniff controller can be used independently of respiration, so even artificially-respirated individuals can benefit from its implementation in end products.
In addition to its use in those end products, the 1-INCH D1-4V-MINI can provide the required accuracy for many other respiratory measurements and other low pressure measurements in medical and other applications.