Heat Shrink Tubing and the Chemistry Behind Its Magic

There’s a lot to be said in favor of getting kids involved in hacking as young as possible, but there is one thing about working in electronics that I believe is best left as a mystery until at least the teenage years — hide the shrink tube. Teach them to breadboard, have them learn resistor color codes and Ohm’s Law, and even teach them to solder. But don’t you dare let them near the heat shrink tubing. Foolishly reveal that magical stuff to kids, and if there’s a heat source anywhere nearby I guarantee they’ll blow through your entire stock of the expensive stuff the minute you turn your back. Ask me how I know.

I jest, but only partly. There really is something fun about applying heat shrink tubing, and there’s no denying how satisfying a termination can be when it’s hermetically sealed inside that little piece of inexplicably expensive tubing. But how does the stuff even work in the first place?

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Souped-Up, Next Gen Wearables

The biggest hurdle to great advances in wearable technology is the human body itself. For starters, there isn’t a single straight line on the thing. Add in all the flexing and sweating, and you have a pretty difficult platform for innovation. Well, times are changing for wearables. While there is no stock answer, there are some answers in soup stock.

A group of scientists at Stanford University’s Bao Lab have created a whisper thin co-polymer with great conductivity. That’s right, they put two different kinds of insulators together and created a conductor. The only trouble was that the resulting material was quite rigid. With the help of some fancy x-ray equipment, they discovered that adding a molecule found in standard industrial soup thickeners stops the crystallization process of the polymers, leaving them flexible and stretchy. Get this: the material conducts even better when stretched.

The scientists have used the material to make both simple, transparent electrodes as well as entire flexible transistor arrays with an inkjet printer. They hope to influence next generation wearable technology for everything from smart clothing to medical devices. Who knows, maybe they can team up with the University of Rochester and create a conducting co-polymer that can also shape-shift. Check out a brief demonstration after the break.

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LEGO Liquid Handler and Big Biology

A career as a lab biologist can take many forms, but the general public seems to see it as a lone, lab-coated researcher sitting at a bench, setting up a series of in vitro experiments by hand in small tubes or streaking out a little yeast on an agar plate. That’s not inaccurate at all – all of us lab rats have done time with a manual pipettor while trying to keep track of which tube in the ice bucket gets which solution. It’s tedious stuff.

But because biology experiments generally scale well, and because more data often leads to better conclusions, life science processes can quickly grow beyond what can be handled manually. I’ve seen this time and again in my 25 years in science, from my crude grad school attempts to miniaturize my assays and automate data collection to the multi-million dollar robotic systems I built in my career in the pharmaceutical industry. Biology can get pretty big in a hurry. Continue reading “LEGO Liquid Handler and Big Biology”

DIY Conductive Glass You Could Actually Make

Transparent, conductive glass is cool stuff and enables LCD panels and more. But the commercial method involves sputtering indium-tin oxide, which means a high vacuum and some high voltages, which is doable, but not exactly hacker-friendly. [Simplifier] has documented an alternative procedure that uses nothing more than a camp-stove hotplate and an airbrush. And some chemistry.

Make no mistake, this is definitely do-it-outside chemistry. The mixture that [Simplifier] has settled on includes stannous (tin) chloride and ammonium bifluoride in solution. This is sprayed uniformly onto the heated glass (350-400° C), and after it’s evaporated there is a thin, strong, and transparent layer of fluorine-doped tin oxide. [Simplifier] reports resistances down in the single-digit Ohms per square, which is pretty awesome. [Simplifier] didn’t get the mix down perfectly on the first pass, of course, so it’s also interesting to read up on the intermediate steps.

Our thoughts immediately spring to masking sections of glass off and building DIY transparent circuits and panels, but we suspect that we’re getting ahead of ourselves. Still, this is an incredible early result, and we hope that it opens up the way to crazy transparent-conductive applications. What would you do if you could make glass circuits? Well, now you can, and it doesn’t look too hard.

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Morbid Battery Uses Blood Electrolyte

Building a battery out of common household products is actually pretty simple. All that is required is two dissimilar metals and some sort of electrolyte to facility the transfer of charge. A popular grade school science experiment demonstrates this fairly well by using copper and zinc plates set inside a potato or a lemon. Almost anything can be used as the charge transfer medium, as [dmitry] demonstrates by creating a rather macabre battery using his own blood.

The battery was part of an art and science exhibition but it probably wouldn’t be sustainable on a large scale, as it took [dmitry] around 18 months to bank enough blood to make a useful battery. Blood contains a lot of electrolytes that make it perfect for this application though, and with the addition of the copper anode and aluminum cathode [dmitry] can power a small speaker which plays a sound-generating algorithm that frankly adds a very surreal element to the art installation.

While we can’t recommend that you try to build one of these batteries on your own without proper medical supervision, the video of the art piece is worth checking out. We’ve seen a few other hacks that involve blood, but usually they are attempting to use it for its intended purpose rather than as an alternative energy source.

Old Batteries Yield Thermite and Manganese

Some people collect stamps, some collect coins, some even collect barbed wire. But the aptly named [Plutonium Bunny] is an element collector, as in one who seeks a sample of as many elements on the periodic table as possible. Whatever, we don’t judge – after all, there are more than a few Hackaday readers who collect lots of silicon, right?

So what’s a collector to do when he gets to the 25th place on the periodic table? Easy – harvest manganese from alkaline batteries with a thermite reaction. There’s a surprising amount of manganese in depleted alkaline batteries, which of course are easy to come by in bulk. The chemistry of [Plutonium Bunny]’s process is pretty straightforward and easy to reproduce with common ingredients, but you’ll want to be careful with a few steps – chlorine gas is not something to trifle with. The basic idea is to solubilize and purify the manganese dioxide from the other materials in the battery cathodes, recrystallize it, and mix it with aluminum powder. The aluminum acts as the fuel, the manganese dioxide is the oxidizer, and once the satisfyingly exothermic reaction shown in the video below is over, the collector-grade elemental manganese can be chipped away from the aluminum oxide slag.

So once you’ve got a few manganese nuggets, what can you do with them? Not much really – it turns out the oxides recovered from the battery are far more useful for things like supercapacitors. But it’s still a neat trick.

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Soda Bicarb Diode Steering Circuit For 7-Segment Display

[Hales] has been on a mission for a while to make his own diodes and put them to use and now he’s succeeded with diodes made of sodium bicarbonate and water, aluminum tape and soldered copper. By combining 49 of them he’s put together a soda bicarb diode steering circuit for a 7-segment display capable of showing the digits 0 to 9.

He takes the idea for his diode from electrolytic capacitors. A simple DIY electrolytic capacitor has an aluminum sheet immersed in a liquid electrolyte. The aluminum and the conductive electrolyte are the two capacitor plates. The dielectric is an aluminum oxide layer that forms on the aluminum when the correct polarity is applied, preventing current flow. But if you reverse polarity, that oxide layer breaks down and current flows. To [Hales] this sounded like it could also act as a diode and so he went to work doing plenty of experiments and refinements until he was confident he had something that worked fairly well.

In the end he came up with a diode that starts with a copper base covered in solder to protect the copper from his sodium bicarbonate and water electrolyte. A piece of aluminum tape goes on top of that but is electrically insulated from it. Then the electrolyte is dabbed on such that it’s partly on the solder and partly on the aluminum tape. The oxide forms between the electrolyte and the aluminum, providing the diode’s junction. Connections are made to the soldered copper and to the aluminum.

To truly try it out he put together a steering circuit for a seven segment display. For that he made a matrix of his diodes. The matrix has seven columns, one for each segment on the display. Then there are ten rows, one for each digit from 0 to 9. The number 1, for example, needs only two segments to light up, and so for the row representing 1, there are only two diodes, i.e. two dabs of electrolyte where the rows overlap the columns for the desired segments. The columns are permanently wired to their segments so the final connection need only be made by energizing the appropriate row of diodes. You can see [Hales] demonstrating this in the video below the break.

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