How to implement accessibility check on arduino?

Question

Arduino

Good afternoon, there is point A, 15-15 cm in size, you need to control this surface, for example, if someone covered it with his hand, then signal it, the light sensor will not work, because when it gets dark it will be difficult to work.
maybe there are some other options?

Answer 1

If we are talking about a person, then there are specialized sensors for the presence of a person.
I have a similar one on the monitor - just bring your hand to the buttons, so for a dozen more sentiments, the backlight of the buttons turns on. This is clearly not a light sensor, since it works equally day and night and works at a great distance.
Such sensors are available.
It is specialized sensors for determining the presence of a human hand.
Can someone tell me the name of this type of sensors, I forgot.

Answer 2

You can make an array of IR sensors working on reflection. If each sensor can control a space of 3x3 cm, then (15x15)/(3x3) = 25 sensors are needed. You can use a capacitive sensor, but the design is an order of magnitude more complicated.

Answer 3

It is not clear what kind of surface, where the surface is, why the surface.
Alternatively, the video camera scans the surface and compares the resulting image with the reference

Answer 4

Whatever the surface - the capacitive sensor will solve your problems. Chuyku just have to adjust.