Making a plate which detects contact with metal

Hello, I'm trying to make a 6" x 6" plate which can detect when a needle comes into contact with it.  The plate can be made out of whatever ( preferably an easy to obtain material like a metal sheet) and have any electrical components necessary attached to it but the needle can't have any attached wires etc.  Any thoughts?

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Downunder35m8 months ago

Get an inductive sensor.

kmforest (author)  Downunder35m8 months ago

I looked into inductive sensors previously and they are pretty much what I needed but I couldn't find any way to get the surface area to be larger. The inductive sensors I found were pretty small, is there anyway to expand the surface area to a 6"x 6" plate size?

What about old school and without technology?
Back in the days we just used two sheets of aluminium foil seperated by some thin plastic foil or cardboard.
One layer right under the skin, the other where you need the right depth.
Good thing about aluminium foil is that there is little no resistance you would feel with a surgical needle.
Downside is that every now and then you need to replace the foil.

Kiteman8 months ago

How hard will the needle be touching the plate?

Will it be attached to anything?

Do you need the plate to send a signal to another device, or just show a visible sign of contact?

kmforest (author)  Kiteman8 months ago

The needles will be standard medical needles anywhere from 15-29 guage

I need the plate to work with any needle someone can just pick up so nothing can be attached to the needle.

I would prefer some kind of electrical output signal so if the needle makes contact I can record the contact.

Kiteman kmforest8 months ago

So you want to register and record a needle being placed on a plate? Are you trying to keep track of equipment during surgery?

What about this?

kmforest (author)  Kiteman8 months ago

something similar, its actually for a medical practice simulator so when you go to far through an analog tissue you will hit the plate and it will alert you. Also I'm no sure if the scale will work since there will most likely be some silicone resting on top of the plate which could throw off the weight measurements by pressing down on the scale when you are going through the silicone.

Kiteman kmforest8 months ago

You need an Energy Stick!

They're available all over the web, but here's an example:

Connect one end to your metal plate, connect the other to the trainee's skin (say, an ankle strap), and as soon as they touch the metal plate with the needle, the Energy Stick will light up and make noises.

Kiteman Kiteman8 months ago

(I forgot to add an image.)