Capacitive touchless sensing

http://sensacell.com/

Can some tell me what kind of sensor they use , how can i make this type of sensing to work with no hands , i meen some objects like a cigarete box..

sorry for my english

REGARDS FROM BULGARIA :)

Depending on the resolution you need, you could do something like this with some High Power IR LED's, and some phototransistors.

There are a lots of ways to do such stuff, none of which being really simple.

If you want to have a "sensitive wall", using reactable-like technology could do it, but it requires a physical contact, no proximity sensing. You can also use light sensors, sensing the light decay when an object gets closer, but you'll need to do some work on calibrating and thresholding to avoid false positives. Capacitive sensors won't do the trick, since they work mostly with only direct skin contact, and probably some objects which delivers a bit of electricity, and certainly not with a cigarette box.

There are a lot of ways to detect a cigarette box, depending mostly on what you wanna do. The examples given on the website are quite different, and gives no hint on your purposes with such technology.

Try to read this http://www.arduino.cc/en/Tutorial/Qt401

There are other sensors in the QT series as well

Remember that it's possible to use an LED as a light sensor as well.

Capacitive sensors won't do the trick, since they work mostly with only direct skin contact,

No that's not true. Capacitive sensors will work at a distance before contact is made. I have got a demo of one where a light is dimmed as you approach it with your hand. However, it does rely on a disturbance to an AC electrical field so a cigarette box will not work unless you lined it with aluminum foil. I would guess the original link uses capacitive sensors.

An other idea is a web cam with some software.

However, unless you are a bit more specific with exactly what you want to sense and in what location you will not get very far.

No that's not true. Capacitive sensors will work at a distance before contact is made. I have got a demo of one where a light is dimmed as you approach it with your hand. However, it does rely on a disturbance to an AC electrical field so a cigarette box will not work unless you lined it with aluminum foil.

Thank you Mike, you're totally right, I didn't mean direct as "touch"... My English is to blame ^^ The important part in my answer was "skin" as opposed to cigarette boxes...

The webcam solution is implemented in the reactable, to which I pointed in my first answer, (as well as in first implementations of Microsoft Surface, AFAIK – which, AFAIK too, now uses iPhone-like multitouch screens) : Basically, a webcam and a projector behind a glass surface, sensing the presence of physical objects on the surface, and sending images reacting to objets behind on the surface.

The reactable software is partially released as free software, but may be a little bit too sophisticated for simple shape detection.

So, syrax, what exactly are you trying to do ? ^^

i planing to make coffee table wich will respond ot any type of objects over. I don’t wanna put webcam or PC :slight_smile: /will be small fashion table/ just wanna know if some object is over the sensor in ~2" . This sensors must be connected to arduino to control array of light on table and may be debuging line to PC

Now my sensors are IR led and phototr. and measure the IR light /peak level of 940nm for this type of photo transistors / if some object reflect light /excluded BALCK objects/

REGARDS

would you mind sharing a bit how you did this? i’ve been wanting to try something similar but have been having trouble finding the right hardware for the sensing.

cheers.

If you're interested in a prebuilt solution, you could use discrete QTR reflectance sensors (QTR-1RC) or QTR reflectance sensor arrays (QTR-8RC). If there isn't a lot of ambient IR, you can detect objects out to around 8 - 10 inches with the RC version. You could also get analog versions (QTR-1A and QTR-8A) and connect them to your Arduino's ADC using a MUX.

We have created an Arduino library (mega168 only at the moment) for interfacing with these sensors:

http://www.pololu.com/docs/0J19/all

  • Ben

i use the same way to sens the motion , and planning to hook all lines with multiplexor for reading more Analog sensors with 1 pin but the problem is that You must cover the sensor to light the led and the lenght between sensors will be ~2inch . that is the reason to find better way for proximity , capacitive way is good but can't sense glass, wood, paper :( and the last i am tune the sensors to work about 1-1.5 inch but the hand and white and black reflect different :)

REGARDS FROM BULGARIA