I have seen projects that use the resistance of objects around us as feedback into an electronic circuit but I didn’t know that inkjet ink was conductive. I would have thought that it would not have been but I guess at least the type that the project creator is using is. Unfortunately I only have laser printers around me these days since I can’t stand the issues surrounded by replacing tiny inkjet cartridges and clogged nozzles. Have a look at this Printed Microcontroller Input Device that Txapuzas Electronics created
Via: Dangerous Prototypes
“You can create a keypad/keyboard using Inkjet printer, paper, tape, and some cables.
Strips made of ink are slightly conductive, as the length of the strip increases, the resistance increases, and as the width of the ink strip decreases, the resistance decreases.
Two ink strips can act as a voltage divider, and when pressing one against the other, the value of the voltage divider changes. Looking at this value you can determine which button was pressed.”