Printing your phone

We tend to think of printing as simply ink on paper these days, but that’s all about to change. Printable electronics is a growing field of research and it holds the promise of being able to use traditional printing processes to produce electrical circuits and even electronic devices like mobile phones.

To print electronics first requires a substrate (think of this as the paper). It’s often a form of flexible plastic that patterns can be printed on to. The patterns are produced by spraying carefully controlled jets of conductive ‘ink’. These form the electrical connections between the devices on the substrate, like the wires of a traditional circuit. Electronics needs more than wires though, it needs active devices like transistors, capacitors and resistors too. How are these produced?

Semiconductor sandwiches

Rather than conductive ink, you can spray on or lay down thin layers of semiconductors. These useful materials lie halfway between being a conductor and a resistor, depending on the voltage that’s applied to them. A sandwich of semiconductor between two conductors can therefore act as a switch. Depending on the voltage applied over the semiconductor it can either pass (as a conductor) or block (as a resistor) current. That means one electrical signal can control another. This is the basis of the transistor, the key component in modern electronics. They can be printed directly onto the substrate and joined up to form complex circuits.

Building gadgets

Electronic engineers are now exploring how to combine 3D printing with printed electronics. In 3D printing, shapes that are designed on a computer can be turned into real objects by printing them as multiple layers of plastic. It’s like building a wall from tiny blocks of plastic. Into these objects can be built printed electronics too, piece by piece.

A gadget like a mobile phone, made up of a plastic case and electronic innards, could be produced quickly and cheaply this way. In fact the sky’s the limit. If you can design the package and the circuits in a computer the technology may soon exist to print it off in its full size usable glory. And in any colour you fancy too.