Archive for the ‘This is how it works’ Category

Have you ever longed for a magic dress that changes itself while you are wearing it? Well, someone has, because it is a trending topic in Ambient Intelligence.

Actually, color change is already solved (up to a point) and the answer is a substance known as thermochrome, that changes colors depending on the temperature. There are two blends of thermochromes: liquid crystals and leuco dyes. The first ones, you have probably seen in (cheap) thingies like mood rings or color changing mugs. Leuco dyes are a combination of colored chemicals that react when temperature goes over 25º C (approximately) and become colorless. The reaction is reversible, so when the temperature drops, they gain their color back. A layer of leuco dyes can be applied to any cloth and the resulting color is the combination of its original color and the substance … until it goes colorless. (Not so) Instant color change!


Picture taken from Del Sol clothing

Of course, heat is kind of ok for a mug, because you can check whether the liquid inside is cold or hot, but not so much for clothes, because temperature tends to change too slow for changes to be too flashy. Other substances can be affected by different stimuli, like light, heat and friction. Lauren Bowker, from the Unseen, worked out a new ink (PHNX) that reacts to seven different parameters in the environment, including air pollution, heat, air friction and moisture. This basically means that your sweater could switch colors when you move from one part of the city to another. Chameleon style!


Image taken from

Cool, right? Well, you don’t have to pretend. I know that when we started talking about color changing fashion, you were thinking of this:

Well, maybe we can’t get exactly this (pity), but, is it actually possible to change textiles at will if we mix thermochromes and electronics. Take, for example, Chromosonic, by Hungarian designer Judit Eszter Karpati. She also relies on a temperature-sensitive dye, but instead of leaving changes to the whims of nature, she has actually woven nichrome wires into the fabric.


Nichrome is a fairly well known alloy of nickel, chromium and other elements that has been widely used as industrial heater. If one heats up the wires in a pattern using, for example, a microcontroller, the dye in the surrounding textile changes colors responding to the pattern, which, in the case of Chromosomic, turns out to be an audio file. Problem is, obviously, that it’s actually way easier to heat things up that to cool them off.


Image taken from Chromosomic (Tumblr)

… or, if you want to stick solely to electronics and make a dress that it’s not just a christmas tree, you can actually sew sensors and LEDs into your fabric and make it sensitive to whatever magnitude you want to measure. Environment Dress, from UH513, won the Next Things 2015 award doing exactly that. Only for the brave people, though!



Anyone has seen Big Hero 6 probably loves the movie. Anyone who’s seen the flick and actually works in robotics probably loves it ten times more. Unlike many (supposedly) historic blockbusters I’d rather not remember, these guys actually enrolled some very well robotics scientists as consultants and the benefits are obvious: most of the basic stuff is scientifically sound.

For a start, let’s focus on microbots. More specifically on swarms.

Swarm robots are (large-ish) groups of robots that work together. Their collective behavior results from local interactions between the robots and between the robots and the environment in which they act. This research field has been active for a long time now and Marco Dorigo is probably one of the best known scientists in it. Swarms work collectively and without explicit centralized supervision. This means that robots have a global goal and a set of rules to follow, but each robot makes decisions on its own. Hence, we get fault tolerant, scalable and flexible systems, i.e. it does not matter that a handful of robots are not working properly, the strength is in the number.

Obviously, if we want to work with a few hundred robots at a time, they need to be cheap, small and battery savvy (imagine you had to recharge 300 robots every few hours!). A good example of this are Rubenstein’s Kilobots (Harvard University).

rubenstein2small-1408024399454Instead of conventional motors, Kilobots make do with smartphone-like vibration motors, much cheaper, lighter and easy on the batteries. When these motors start to vibrate, they change the center of mass of the robot, actively displacing it forwards (imagine someone pushes you a bit when you are standing: you need to move to regain equilibrium, right?). This is actually the basis of a classic workshop for kids to build the simplest robot using a toothbrush and a smartphone vibration motor.

If you have two motors, one on each side of the robot, you can also rotate right and left by activating one or the other. Kilobots also talk with each other via infrared communication. Thus, they can calculate approximately where they are with respect to the rest. Using this information, they can collectively adopt any shape simply following three simple rules: edge-following, gradient formation and localization.


The system works as follows. We give ALL robots information about the shape they must adopt and fix a small number of (stationary) robots in a corner of the shape (that becomes our origin of coordinates, i.e. the 0 km of our reference). The rest of the robots will try to estimate their position within the shape with reference to these robots (i.e. the coordinate system). They also keep information about how many robots are between these static robots and themselves (gradient). Robots basically move by following the frontier of the global robot formation (edge following). They keep moving until they decide that they are within the boundaries of the desired shape and they stop when they detect that they are about to leave those boundaries or they collide with a robot with the same gradient value. After a while (unfortunately, several hours, unlike in Big Hero 6) robots manage to organize themselves into the desired shape. Taking into account that we are talking about more than 1000 robots and only these simple rules are used, this is quite a big deal.

So, yup, just planar shapes and quite slow with respect to the movie, but definitely in the same line!

More information on IEEE Spectrum and How Stuff Works

Most likely, the most coveted gadget in Back to the Future II was Marty’s (pink) hoverboard. This is probably why in 2014 the so called HUVr Tech company played a major prank on gullible consumers and, under the motto “The Future has Arrived”, released a commercial where Tony Hawk himself, as well as other celebrities, explained how well their new hoverboard actually worked. The disappointment among eager consumers was so huge that Hawk and the others had to apologize to the public later for their participation in the “joke”.

This is also probably why Hendo Hoverboards talked Hawk into trying their own hoverboard when they went to Kickstarter for funds.


After the HUVr Tech fiasco, their proposal was probably received with skepticism and it was less than likely that someone would back the 10000 USD to purchase one of their first platforms. However, their Hawk video actually looks more realistic: the hover is almost touching the floor and its not that stable, either.

It’s not like they are going to explain how they do it, but taking into account the platform motion and how the floor looks, the secret beneath might be Lenz’s Law. One might have actually watched a popular science-fair trick: drop a magnet inside a copper tube and its fall will slow down considerably or even stop.


Lenz’s law states that an induced electromotive force always gives rise to a current whose magnetic field opposes the original change in magnetic flux. The idea is basically that when the magnet falls into the conductor, it generates a current and, hence, a magnetic field, that is bound to oppose the fall of the magnet.


The only requirement for this effect is that the conductor must be non-magnetic, that is every metal except iron and steel. The best choice to obtain a strong current would be silver, but for obvious reasons one has to do with copper or aluminium (in this order).

Hard core physicians may find a more detailed explanation on how Lenz’s law works on a plane in here.  Unfortunately, a magnet falling slowly through a pipe is not evidence enough than a board will be able to keep your average person on air, right? The trick might be to arrange magnetic fields properly and feed them enough power. And to have a metallic non magnetic floor, too.

Even if they manage to develop this as a product, there are strong limitations to its use, plus its mobility seems to be severely restricted. However, if you have 10000 USD to spare and want to give it a go, here’s their kickstarter. You are on your own, though!