SparkFun Forums

[Alterscapes]

I'd like to outfit a stuffed animal with a sensor that can determine when it is being hugged, to trigger an audio player and some other electronics inside. Any thoughts on how best to accomplish this?

What I think of is either a very large equivilant of a reed switch that's closed by compressing two contacts seperated by something spongy in the bear's chest cavity, or maybe something involving a sealed rubber bladder and an air pressure sensor. Thoughts on where to source/how to homebrew parts?

[Philba]

I don't think the toys you buy use anything very fancy - just contacts separated by some compressible foam.

[SOI_Sentinel]

I actually like the air pressure sensor idea. You could trigger a few different responses depending on how hard they squeeze... of course, the top end "Help help, they're trying to strangle me!" line would not be appropriate for small children's toys. Freescale sources various air pressure sensors, and I know I can get rubber bladders from American Science and Surplus (air pressure cuffs).

I believe that most sound box squeeze units are really just two plastic shells with a spring and two contacts. The compressible foam may as stated by Philba would be a "softer" variant.

[mare]

I just bought talking dog for my one year daughter. It has metal contacts in legs and they are very sensitive.


For using air pressure you may think about some cheap water level sensors from washing machine. There are models with small dimensions and they operate below 100mbar.

[Alterscapes]

Thank you for the feedback, all. I'll look into those air-pressure sensors..

[bertrik]

Perhaps you can find some ideas here:
http://www.hackfurby.com/

[propellanttech]

What about a true pressure sensor.

Check this out and see what you think. Would be real ease to interface with also:

http://www.parallax.com/detail.asp?product_id=30056

James L

[Philba]

that sensor is pretty pricey. also, it might be a bit too stiff for a toy - 100 lbs for 4.2V output. I suspect a toy only needs around 10 lbs.

You can make your own pressure sensors with that conductive foam that they ship DIP ICs on. I've experimented with it and it works fairly well. Just take 2 small, same size pieces of PCB material, solder wires to each copper side and cut a piece of the foam about 1/4 inch larger. make a sandwich with them, hook up an ohmmeter to each wire and then squeeze. The resistance will change. I doubt it will work reliably in the long term but for a toy, it might be ok.

[Bushman]

One idea is to take some of that conductive foam that you get all your electronics parts stuck in when you order them and put a contact on either side.

As the foam is compressed, the resistance between the plates goes down.

You could use this to get analog hugging values instead of just a simple hugged not hugged information


Edit: woops, didnt read the other replies, someone mentioned it already.