So I know someone who has a problem plucking their hair, and I want to help them by making a wristband that vibrates whenever it gets close to their head. Problem is, I do not know what sensor I should use.
I am thinking about using a gyroscope and magnetometer duo to sense the orientation of their hand. When N is facing upwards and the gyroscope is vertical in the Z axis, then it will vibrate and indicate that their hand is at their hairline.
Would this be an efficient approach or is there another sensor that could be used? I was also thinking about an ultrasonic sensor to detect when anything got close to their head, or maybe even dual sensors that sense when they are close to each other.
What do you all think?