# Passive proximity detection using metal plate-capacity

For some specific product, we need to create a proximity sensor of 50-100cm using a capacity sensing .(no PIR, no infra,no ultrasonic)

Reading on the net, haven't provide me what i needed .

So, i am trying to get some direction on how do you calculate the plate surface area and thickness, in relation to the maximum distance of detection of a human body .

The software probably much easier, although i will also need to find a way so that it can awake the controller only on detection .

Is there something like that, or is this a very wrong direction ?

thanks .