How does a bubble jet printer work?

A bubble jet printer uses a principle as old as mud bubbling out of the ground. Have you ever noticed that when bubbles pop, a little of the liquid gets propelled outward?

Sure you have, —think of the misty feeling you get when you put your nose up to ginger ale, or the stickiness that sometimes happens if you’re too close to a gum bubble when it pops.

Anyway, popping bubbles inspired inkjet printer designers who wanted to propel a microscopic dot of ink onto a piece of paper quickly and on command without actually touching the paper. A bubble jet print head typically has 300 to 600 microscopic nozzles, and a tiny amount of ink waits inside each nozzle.

As the print head quickly stops and starts along the page, so quickly that it seems like a continuous motion, jolts of electricity heat up a resistor in the nozzle.

This heat instantaneously boils the ink, vaporizing it into a bubble and launching it from the print head to dot neatly onto the surface of the paper.

How small are these neat little splatters? It can take dozens of them, precisely fired, to make up a single letter on the page.