Touch switch with conductive ink as thin as possible

Question

First for all. Am not an electrical enginner, am just an amateur artisan, pretending make intetesting gadgets.

So the situation is this. I need to make a circuit in a sheet of paper for just turn on and turn off a very very little led light. The challenge: make this as thin as possible. Ideally with 0.5mm of thickness.

What I already made: I found a very interesting example in this link https://www.electroschematics.com/5996/touch-switch-circuits/

But the problem is, again, the thickness, only the ic 555 has a 3.5 mm, for me its to much. In summary, is there another way to do this circuit but in a very very thin way?.

You could get close. http://www.ti.com/lit/ds/symlink/lmc555.pdf Look at page 29. The max height of the DSBGS is 0.575mm. The problem is going to be attaching it and making sure that it's reliable. — vini_i, Jul 09 '19 at 20:07
5 volts (safe for the human hand) and 100,000 ohms (between fingers)produces 50uA which should make a LED glow. — analogsystemsrf, Jul 10 '19 at 03:33

score 0 · Answer 1 · answered Jul 09 '19 at 22:35

If all you need is a very weak light, use a neon lamp and a safe, low current power supply. Bridging two conductive ink traces between the lamp and supply with a finger would light the lamp. Using audio-frequency or low frequency RF would make the circuit easier to turn on, since it would bypass skin resistance with capacitive coupling.

score 0 · Answer 2 · answered Jul 10 '19 at 01:01

0.5mm rules out most packaged ICs (that’s about the thickness of a sawn wafer.) If you could use chip-on-board it’s possible, or something in chip-scale packaging you might be able to make that.

That said, a Silego GPAK device gets pretty close, at about 0.75mm.

You didn’t mention your battery - how are you dealing with that?

More: have a look here. Some candidates that meet your criteria possibly. What are the smallest microcontrollers?

Touch switch with conductive ink as thin as possible

2 Answers2