The sensor can measure blood pulse rate in real time when placed on the wrist and neck. The sensor was also tested for its ability to monitor respiration; When placed on the throat, the sensor could detect changes in pressure when different words were pronounced. Interestingly, the fabricated sensor also showed good sensitivity in detecting large-scale motion monitoring, as in the case of bending and extension of finger joints.
“While researchers have been working to develop sensors that can detect very small change in pressure, our pressure sensor is able to detect both small-scale motion caused by low pressure (less than 2.7 kPa) and large-scale motion at high pressure,” says the team. “The sensor exhibited good flexibility and reproducibility over 5,000 cycles.”
“When you speak, the throat muscles respond differently based on the change in pressure. The vocal muscles undergo different motions when different words are pronounced. The sensor was able to detect the slight change in pressure when different words were said,” say the IIT Bombay researchers, who collaborated with researchers from Cambridge and Monash University, Australia.
The researchers tested its sensitivity in recording the difference in pressure when different words were said, and when the same word was repeated several times. “The sensor can be used as a word-recognition device. This is only preliminary work and more has to be studied before the sensor can be used for speech recognition,” says the team.
In the case of finger bending and extension, which involves monitoring the large-scale motion, the sensor showed high sensitivity. The sensor generated different current signals when the index finger, to which it was attached, was bent. The current signal was the least when the angle of bending was small (15 degree) and maximum when the angle was high (90 degree). “We have not tested the change in pressure due to change in direction of movement of the finger,” the team clarifies.