Now what I understand is our human body or a stylus disturbs the electrostatic field of a capacitive screen and thus the mobile calculates the disturbance and does some math and registers a touch.

Now what if I take a thin tube and fill it with some kind of electrolyte (like Vinegar or Salt Water) then put a cotton swab on one end and then use it as a stylus. What will happen...?

Edit: So I tried it with Normal Tap Water. So I had a bit of mixed results sometimes it worked sometimes it didn't. And it did get messy. Now I have to somehow make it efficient.

  • 3
    \$\begingroup\$ Try it at home. Your screen will get wet. \$\endgroup\$
    – Transistor
    Commented May 31, 2018 at 17:16
  • \$\begingroup\$ Whatever you do, you need to match the impedance of the human body, it is possible, but may take a lot of experimentation. \$\endgroup\$
    – Voltage Spike
    Commented May 31, 2018 at 17:36
  • \$\begingroup\$ What's the other end of the tube connected to? You may make an artificial finger, but it has to be connected to an artificial carcass. \$\endgroup\$ Commented May 31, 2018 at 19:25
  • \$\begingroup\$ @laptop2d: No, you don't need to "match the impedance of the human body". All you need to do is provide a conductive path to the human body. An electrolyte-filled tube can do the job just as well (if somewhat more messily) as a metal rod or a carbon-loaded elastomer. For example, the Saw Stop Demo shows that a hot dog makes a good stand-in for a finger. It'll make your phone screen all greasy, however. \$\endgroup\$
    – Dave Tweed
    Commented May 31, 2018 at 22:30
  • \$\begingroup\$ @DaveTweed What about the capacitive sensors? It's my understanding that you have to match the same capacitiance and resistance of the human finger. \$\endgroup\$
    – Voltage Spike
    Commented May 31, 2018 at 23:04


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