I want to detect a childs hand

[VISHOK]

hi friends,
I am working for a project which involves sensing a childs hand in its very first stage.The sensor should be effective from a distance of 1foot radially.Or i can use 3 such sensors to cover all directions.Since this involves human sensing we have to keep in mind any radiations from the primary sensor/circuit should not effect the child skin."Is that possible to detect a childs hand"

 

[vaineo]

It wouldn't be hard to do if it doesn't matter if it's a child or not. if your only looking for an object going to close to something you could probably use infrared or ultrasonic. If you only want it to detect living things, maybe a pyroelectric sensor. I saw something like that in EPE.

 

[ConKbot of Doom]

I would think that you could use a Qtouch sensor IC. They are normaly touch sensors, but if you use a conductive electrode with no di-electric on top, then they have proximity sensing. The sensitivity of the chip goes up as you increase the sense cap size, (you would think it would be the other way) and the max is 200nf (.2uf) so get a QT110 series chip an use a small metal sphere (isolated from ground as well as possible) as the sensor and you may get a 1' range. If you can control the flooring, a grounded matt may help out with the range by giving the person better ground coupling.