Conductive Silicone Makes Flexible Circuits

Flexible circuits and wearables seem to be all the rage these days. We’ve got conductive paint, glue, and even thread. So how about conductive silicone? Well, as it turns out — it’s not that hard to make.

[Andrew Quitmeyer] has been researching flexible circuits for a while now, and recently stumbled upon an expired patent for flexible ignition cables, using carbon fibers mixed with a conductive silicone. He started playing around with it, and discovered that by dissolving pieces of carbon fiber in rubbing alcohol, letting it dry, and then mixing it into a 2-part silicone you get pretty good electrical conductivity. In fact, in the range of 40-150ohms, which is actually pretty darn impressive!

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7th Period of the Periodic Table Complete

For the last fifty or so years, the periodic table has been incomplete. Elements after uranium on the periodic table have been synthesized for the past few decades, but there were always a few missing blocks in the periodic table. These elements, with atomic numbers of 113, 115, 117, and 118 comprise the missing parts of period 7 – the lowest row – of the periodic table. Now, IUPAC, the International Union of Pure and Applied Chemistry, has announced the verification of the discoveries of the last four elements of the seventh period of the periodic table.

With the announcement of the verification of discovery for these elements, they will get a name. Currently elements 113, 115, 117, and 118 are known as Ununtrium, Ununpentium, Ununseptium, and Ununoctium, respectively. What these elements will be named depends on the proposals by the discoverers of these elements.

Element 113 was discovered by researchers at the RIKEN laboratory in Japan, and these researchers will be able to propose a name and atomic symbol for their discovery. Elements 115, 117, and 118 were discovered through a partnership between the Joint Institute for Nuclear Research in Dubna, Russia, Lawrence Livermore National Laboratory in California, and Oak Ridge National Laboratory in Oak Ridge, Tennessee. Researchers at these three laboratories will propose names and atomic symbols for these three elements.

It should be noted that Lawrence Livermore National Laboratories and the Joint Institute for Nuclear Research in Dubna each have their own element named after them: Lawrencium and Dubnium, with atomic numbers 103 and 105, respectively. Having element 113, 115, and 118 named after Oak Ridge National Laboratory wouldn’t be a bad proposal, and would be rather fitting given the laboratory’s influence on the last half-century of physics.

Of particular interest is the naming of element 118. Because element 118 falls within group 18 of the periodic table, it is a noble gas, with a particular naming pattern. each of the elements in group 18 end with the suffix ~on, instead of the suffix for the rest of the periodic table, ~ium (helium is the exception to this rule due to historical precedent). Whether element 118 will use the ~on or ~ium suffix is up to debate; current IUPAC rules say all new elements should end with ~ium, but recommendations have been published to name all group 18 elements with the ~on suffix.

This is not the end of the periodic table by any means. It is possible that elements with higher atomic numbers can be synthesized. However, experiments to synthesize element 119 have so far come up short, and the predicted properties of element 119 put it at the limits of what current technology is able to detect.

The Mystery of the Boiled Batteries

While debugging a strange battery failure in a manufacturing process, [Josh] discovered a new (to us) LiPo battery failure mode.

Different battery chemistries react differently to temperature. We’ve used lithium exclusively in high-altitude ballooning, for instance, because of their decent performance when cold. Lithium batteries generally don’t like high temperatures, on the other hand, but besides the risk of bursting into flames, we had no idea that heat could kill them. When the battery’s voltage is already low, though, it turns out it can.

[Josh]’s process required molding plastic with the battery inside, and this meant heating the batteries up. After the fact, he noticed an unreasonably high failure rate in the batteries, and decided to test them out. He put the batteries, each in a different initial charge, into a plastic bag and tortured them all with ice and fire. (OK, boiling water.)

When the batteries got hot, their voltage sagged a little bit, but they recovered afterwards. And while the voltage sagged a little bit more for the batteries with lower initial charge, that’s nothing compared to the complete failure of the battery that entered the hot water with under 1V on it — see they yellow line in the graphs.

battery_voltages

There’s a million ways to kill a battery, and lithium batteries are known not to like being completely discharged, but it looks like the combination of deep discharge and heat is entirely deadly. Now you know.

What Can Happen When You Do Try This At Home

In somewhat of a countdown format, [John McMaster] looked back over the last few years of projects and documented the incidents he’s suffered (and their causes) in the course of doing cool stuff.

[John] starts us off easy — mis-wiring and consequently blowing up a 400V power supply. He concludes “double-check wiring, especially with high power systems”. Other tips and hazards involve situations in which we seldom find ourselves: “always check CCTV” before entering the experiment chamber of a cyclotron to prevent getting irradiated. Sounds like good advice.

hotplate[John] also does a lot of IC decapping, which can involve both heat and nasty acids. His advice includes being ready for large spills with lots of baking soda on hand, and he points out the need to be much more careful with large batches of acid than with the usual smaller ones. Don’t store acid in unfamiliar bottles — all plastics aren’t created equal — and don’t store any of it in your bedroom.

The incidents are listed from least to most horrible, and second place goes to what was probably a dilute Hydrofluoric acid splash. Keyword: necrosis. First place is a DIY Hydrochloric acid fabrication that involves, naturally, combining pure hydrogen and chlorine gas. What could possibly go wrong?

Anyway, if you’re going to do “this” at home, and we know a bunch of you are: be careful, be protected, and be prepared.

Thanks [J. Peterson] for the tip!

Lise Meitner: A Physicist who Never Lost her Humanity

It is said that the first casualty of war is the truth, and few wars have demonstrated that more than World War II. One scientist, whose insights would make the atomic age possible, would learn a harsh lesson at the outset of the war about how scientific truth can easily be trumped by politics and bigotry.

Lise Meitner was born into a prosperous Jewish family in Vienna in 1878. Her father, a lawyer and chess master, took the unusual step of encouraging his daughter’s education. In a time when women were not allowed to attend institutions of higher learning, Lise was able to pursue her interest in physics with a private education funded by her father. His continued support, both emotional and financial, would prove important throughout Lise’s early career. Continue reading “Lise Meitner: A Physicist who Never Lost her Humanity”

Chewing Gum Plus Carbon Nanotubes

Normally, strain sensors are limited in their flexibility by the underlying substrate. This lead researchers at the University of Manitoba to an off-the-wall solution: mixing carbon nanotubes into a chewing-gum base. You can watch their demo video below the break.

The procedure, documented with good scientific rigor, is to have a graduate student chew a couple sticks of Doublemint for half an hour, and then wash the gum in ethanol and dry it out overnight. Carbon nanotubes are then added, and the gum is repeatedly stretched and folded, like you would with pizza dough, to align the ‘tubes. After that, just hook up electrodes and measure the resistance as you bend it.

The obvious advantage of a gum sensor is that it’s slightly sticky and very stretchy. The team says it works when stretched up to five times its resting length. Try that with your Power Glove.

We’ve seen a couple different DIY flex sensor solutions around these parts, one based on compressing black conductive foam and another using anti-static bags, but the high-tech, low-tech mixture of nanotubes and Wrigley’s is a new one.

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Thomas Midgley, GM, and the Dark Side of Progress

Scientific improvements that create industries and save millions of lives often come at a price that isn’t revealed until much later. Leaded gasoline helped the automobile industry take off and synthesized Freon extended the lifespan of lifesaving vaccines, but they took an incredible toll on the environment.

Both were invented in the early 20th century by Thomas Midgley, Jr. After graduating from Cornell in 1911 with a degree in mechanical engineering, he worked briefly for National Cash Register where inventor Charles Kettering had just created the first electronic till. In 1916, Midgley started working for Kettering at Dayton Metal Products Company, which soon became the research division of General Motors.

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