Color changing pen

There are a lot of pen patents out there that claim to be color changing pens with all sorts of fantastic capabilities, however, the majority of those pens are based on ink-jet printer technology and depend on the ejection of ink from some orifice onto the workpiece. I propose a color changing pen which uses microfluidics to mix the ink, and which uses the normal ink flow characteristics of the classic pen nibs (fountain tip, ball point, ...).

One of the primary benefits of this technique is that the pen would write like a pen. There is no switch to turn it on and off, it just flows when it needs to flow.

My current estimates are that a color change could happen in ~ 1 second in a preliminary model. As the change gets faster and faster, more cool techniques arise for creating art. You could read a picture into the pen memory and simply scribble back and forth on a piece of paper while the ink color changes to match the color of the picture. This would end up with wildly fantastic pieces of art or crud, but either way it would be cool.

Additionally, the pen would be programmable in many different ways with a variety of sensors available. An online sharing website would be built to share the user developed programs.