Materials That Trigger Capacitive Touch Screen, (iPad or iPhone)

Hi, I've been Googling for capacitive materials to operate touch screens.

I am trying to find out if there are any materials out there that can be used on the Apple iPhone or iPad, without conducting the human finger's bioelectricity.

I can find lots of capacitive styluses out there, but they all seem to work by holding them with your hands. The application I am looking for, however, is controlling an iPad without human touch involved.

For instance, a material that will be detected by the iPad screen when you lay the iPad flat on the table and simply place a small circular piece of said material on the screen and then let go of it.

Or, as a second example, a small spherical object (like a marble) that rolls over the iPad and triggers the capacitive screen even when no human is touching it.

Perhaps there are any ideas about this?

Or would it simply be impossible because there is always some electricity needed in the object that is touching the screen? Would it, in that case, be possible to build a small battery-powered device that triggers the screen?

Hope you can help,
Thanks!

The first step is to determine the exact type of touch screen used, as there are several different methods.
It should be possible to activate any of them without a human touch.

Yep. Get a monkey...

Yep. Get a monkey...

surplus dell tech support employees ?

Or go to a med school & buy a finger...

I have been in contact with Jeff Rowberg from http://www.keyglove.net/ and he replied:

you might try metalized mylar ... the kind used in those fancy gift balloons .

It must be easier ways to register loose marbles?

TOK

I've experimented with this a lot and have yet to find any material that will be recognized as present on the surface of an iPhone or iPad without a human body in very close (<a few mm) proximity or in direct contact. None of the materials mentioned here (silver nylon fabric, conductive mylar, conductive silicone...) will work if put at the end of a long wooden dowel. It is an easy experiment to try.

I'm curious if anyone has actually found a material that will work. I believe that you need to simulate the dielectric of a large mass of human flesh to get this to work and I know of no materials that would do this.

This is certainly open to lots of clever and funny responses...if you have any serious ideas please post them. Thanks.

How about an actual capacitor?

hmmm ...
if you could describe the actual developmental application/end use this may help in figuring out a solution .
for example , if the "ball on a stick" is to be used as an assist to limited mobility individuals then a conductive strip/wire in the stick might work .

^ Yes, there are a few touch screen technologies, human capacitance is not one of the leaders.

The application will be to position items on the screen and the let go of them. (like a chess board). This means the human hand, or indeed the entire body, will not be in contact with the item that is placed on the screen.

Another application will be to roll a real physical marble over the iPad screen and detect it's position, without it being touched.

Then you want an acoustic one. Google acoustic touch screen

....or IR or another "imaging" modaility

But is there any material that will work with (arguably) the current most widely distributed Consumer Electronics touch screen technology, Capacitive (ie iPhone, iPod Touch, iPad)?

a few years back i seen *something* about a touch pad that used resistive X/Y determination .

^Yes, they exist too. Basically, apply a voltage across X and measure the voltage on Y (floating). Then swap to voltage across Y and measure X. This gives X,Y coordinates.

As the originator of what's quoted here, I'd just like to say that it not correct (as was pointed out above). I didn't actually try the wooden dowel trick until I saw this post saying I was wrong, and lo and behold, it doesn't work the way I predicted.

While the experiments I've done don't require direct contact, the silver nylon fabric does work if the fingertip is in very close proximity. It is also possible that since, in my particular design, each fabric sensor is a floating I/O line and has a very small (but virtually constant) electrical charge on one end, this makes a difference.

But yes, the fabric all by itself, far away from any charges, does nothing on my iPad screen. I apologize for the incorrect information.

Funnily enough,
this post has been edited by yours truly .
honestly , i cannot figure out what the hell monkeys and bananas have to do with this topic that has been dead for quite some time .

you've got my attention .

This post has been edited by CWB on December 04, 2011 02:19 pm

I read this thread with interest. Is it possible to embed a battery in something (hopefully a watch battery or something similar) to trigger touch on capacitive screens? I have in mind a board game played on an ipad's screen with a few figurines, but similarly to the person who started this thread I'm having difficulty coming up with any way for the ipad to reliably detect the position of the figurines on the map.

Great news for everyone! It seems that anti static film is the best solution to operating a capacitive touch screen without the aid of human skin. Here is the link to the site that I read about this material: How To Make A Free Capacitive Stylus
There's even a video to prove that it works! (this should work great for the figurine game!)

hmmm ...

have you tested this in a manner as the guy alluded to near the end of the video ?
"... and you have to wear gloves ..."

also , a thin covering with a soft material (cotton cloth ?) will help prevent scratching the working surface of the screen .