Changing Color Under Pressure

When you saw the picture for this article, did you think of a peacock’s feather? These fibers are not harvested from birds, and in fact, the colors come from transparent rubber. As with peacock feathers, they come from the way light reflects off layers of differing materials, this is known as optical interference, and it is the same effect seen on oil slicks. The benefit to using transparent rubber is that the final product is flexible and when drawn, the interference shifts. In short, they change color when stretched.

Most of the sensors we see and feature are electromechanical, which has the drawback that we cannot read them without some form of interface. Something like a microcontroller, gauge, or a slew of 555 timers. Reading a single strain gauge on a torque wrench is not too tricky, but simultaneously reading a dozen gauges spread across a more complex machine such as a quadcopter will probably require graphing software to generate a heat map. With this innovation it could now be done with an on-board camera in real-time. Couple that with machine learning and perhaps you could launch Skynet. Or build a better copter.

The current proof-of-concept weaves the fibers into next-generation bandages to give an intuitive sense of how tightly a dressing should be applied. For the average first-aid responder, the rule is being able to slide a finger between the fabric and skin. That’s an easy indicator, but it only works after the fact whereas saying that the dressing should be orange while wrapping gives constant feedback.

Robo Rainbow graffiti machine

[mudlevel] built this rainbow graffiti producing robot for an art exhibit in San Diego. While there are no build details we can easily pick this apart from the pictures. Looks like the brains are an arduino, the drive is a power drill with the trigger removed, and a few other servos for firing the spray cans.  The counter weighted arm for creating the rainbow was a pretty good idea too. Watching this, we had an idea for a super simple purely mechanical way to do this that would be similar to a catapult.  You could use the motion of the trailer to “wind up” the counter balance with a simple ratcheting spool of string attached to the axle. Engage your spray cans and let the balance drop and you’re done.  Pedal on to re-wind the counterbalance for another rainbow.

Man made rainbow uses ONLY sunlight and rainwater

This rainbow is and is not natural. It’s the product of rainwater and sunlight so in that respect it’s natural. But as you can see, it’s not raining. This is an art installation that uses captured rainwater, stored solar electricity, and irrigation equipment to float a heavy blanket of mist in the air. The prismatic effects of the suspended water particles separate the sunlight into various bands by wavelength and a rainbow springs into existence.

We’ve done this before with a garden hose in the back yard. It might be fun to try to build a version that recycles the water as this does, perhaps using a rain barrel as a reservoir. It would certainly be much easier than pulling off that water-based 3-D display we’ve been meaning to undertake.

[Thanks Xb0xGuru]