Stretchable Traces for Flexible Circuits

Electronic components are getting smaller and smaller, but the printed circuit boards we usually mount them on haven’t changed much. Stiff glass-epoxy boards can be a limiting factor in designing for environments where flexibility is a requirement, but a new elastic substrate with stretchable conductive traces might be a game changer for wearable and even implantable circuits.

qxMo1DResearchers at the Center for Neuroprosthetics at the École Polytechnique Fédérale de Lausanne are in the business of engineering the interface between electronics and the human nervous system, and so have to overcome the mismatch between the hardware and wetware. To that end, [Prof. Dr. Stéphanie P. Lacour]’s lab has developed a way to apply a liquid metal to polymer substrates, with the resulting traces capable of stretching up to four times in length without cracking or breaking. They describe the metal as a partially liquid and partially solid alloy of gallium, with a gold added to prevent the alloy from beading up on the substrate. The applications are endless – wearable circuits, sensors, implantable electrostimulation, even microactuators.

Looks like progress with flexibles is starting to pick up, what with the conductive silicone and flexible phototransistors we’ve covered recently. We’re excited to see where work like this leads.

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[Cody] Takes us From Rock To Ring

[Cody Reeder] had a problem. He wanted to make a ring for his girlfriend [Canyon], but didn’t have enough gold. [Cody and Canyon] spent some time panning for the shiny stuff last summer. Their haul was only about 1/3 gram though. Way too small to make any kind of jewelry. What to do? If you’re [Cody], you head up to your silver mine, and pick up some ore. [Cody] has several mines on his ranch in Utah. While he didn’t go down into the 75 foot deep pit this time, he did pick up some ore his family had brought out a few years back. Getting from ore to silver is a long process though.

splattersFirst, [Cody] crushed the rock down to marble size using his homemade rock crusher. Then he roasted the rock in a tire rim furnace. The ore was so rich in lead and silver that the some of the metal just dropped right out, forming splatters on the ground beneath the furnace. [Cody] then ball milled the remaining rock to a fine powder and panned out the rest of the lead. At this point the lead and silver were mixed together. [Cody] employed Parks process to extract the silver. Zinc was added to the molten lead mixture. The silver is attracted to the zinc, which is insoluble in lead. The result is a layer of zinc and silver floating above the molten lead. Extracting pure silver is just a matter of removing the zinc, which [Cody] did with a bit of acid.

Cody decided to make a silver ring for [Canyon] with their gold as the stone. He used the lost wax method to create his ring. This involves making the ring from wax, then casting that wax in a mold. The mold is then heated, which burns out the wax. The result is an empty mold, ready for molten metal.

The cast ring took a lot of cleanup before it was perfect, but the results definitely look like they were worth all the work.

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Golden Commodore C64 Brings the Bling to 8-Bit Computing

Sometimes, a hack is just a hack. And sometimes, a hack is nothing but a gold-plated Commodore C64.

Alright, it’s not gold-plated, it’s gilded. For the uninitiated, gilding is the process of gluing gold powder or gold leaf to an object. Gold is amazingly ductile – a tiny nugget 5mm in diameter can be hammered into a sheet of gold leaf that can cover about a half a square meter. It’s extremely thin and delicate and has to be handled very gingerly, and the gilder’s craft is therefore very meticulous. For more on gilding, see this post on signmaking with gold leaf.

[thefuturewas8bit], who runs a vintage Commodore web store, did a great job gilding a C64 case, just because. The attention to detail is fantastic – notice that even the edges of the keyboard cutouts are gilded and burnished. A nice finishing touch is swapping out the stock red power LED for a yellow one – red simply clashes too much. Lest you think there’s nothing to learn from a purely aesthetic hack, [thefuturewas8bit] shares a great tip for removing the metal badges from a plastic case – spray them with freeze-spray from the back to pop off the glue. No need to dig at them with a screwdriver and gouge or bend them. Nice trick.

Any hack can earn extra points for style, and we think that gold works well on the C64.  But if gold is a little too overstated for you, you can always try to score a colorful new injection-molded case for your vintage Commodore.

Salvaging Gold From Old Electronics

If you’re hoarding old electronics like us, there’s a good probability you have a decent amount of gold sitting around in cardboard boxes and storage containers. Everything from old PCI cards, IC pins, and even printers have a non-negligible amount of precious metals in them, but how do you actually process those parts and recover that gold? [Josehf] has a great tutorial for gold recovery up on Instructables for the process that netted him an ounce of gold for three months’ work.

After cutting up a few circuit boards to remove the precious gold-bearing parts, [Josehf] threw these parts into a mixture of muriatic acid and hydrogen peroxide. After a week, the acid darkened and the gold slowly flaked off into dust. This gold dust was separated from the acid by passing it through a coffee filter and readied for melting into a single nugget.

Gold melts at 1064 ˚C, much hotter than what can be obtained by a simple propane torch. This melting point can be reduced by the addition of borax, allowing the simplest tools – a propane torch and a terra cotta crucible – to produce a small gold nugget.

For three months of collecting, stripping, and dissolving electronic parts, [Josehf] netted 576.5 grains of gold, or at current prices, about $1500 worth of the best conductor available. Not too bad, but not something we’d use as a retirement plan.

Thanks [Matthias] for sending this in.

AuPod, the solid gold iPod nano watch

aupod

 

The 6th generation iPod nano makes a wonderful watch, but something milled out of aluminum doesn’t lend itself to more formal events. [Ted] liked the idea of an iPod nano watch, but wanted to kick things up a notch and fabricate an 18k gold iPod nano. It took 500 hours and $2500 in materials, but we’d say it’s worth it.

The new 18k gold enclosure for the watch was fabricated using the lost wax casting method. First, all the electronics and buttons were removed from the iPod, then a negative mold was made in silicone rubber. A positive wax mold was made with the silicon mold, and finally another negative mold – this time in plaster – was made by vaporizing the positive wax mold in a furnace.

[Ted] used two one-ounce coins as the source of gold for his nano enclosure, spun into the plaster mold. From there, it’s just a simple but tedious matter of cutting the sprues off, shaping, filing, buffing, and polishing. With a new leather strap, the iPod is reassembled in its new enclosure.

Wonderful work, and amazingly impressive from someone who doesn’t consider himself a jeweler.