Resistance in Motion: What You Should Know About Variable Resistors

Adjusting the volume dial on a sound system, sensing your finger position on a touch screen, and knowing when someone’s in the car are just a few examples of where you encounter variable resistors in everyday life. The ability to change resistance means the ability to interact, and that’s why variable resistance devices are found in so many things.

The principles are the same, but there are so many ways to split a volt. Let’s take a look at what goes into rotary pots, rheostats, membrane potentiometers, resistive touchscreens, force sensitive resistors, as well as flex and stretch sensors.

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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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This long bike is built for haulin’. After needing to find a truck to transport his welding equipment (ironically in order to build another bike) [Nick Johnson] decided it was time to make a two-wheeled cargo transport. He extended the frame in order to add a cradle in the front. Eventually there will be sides on that box but for now it works like a charm for transporting his groceries. With the long wheel-base this should be pretty stable as long as you balance your cargo. We’d certainly be more apt to try a ride on this rather than the double-decker death-trap from a few weeks ago.

Make a stretchy fabric USB cable

Stretchy fabric USB cable
If you’ve been puzzled over a discreet, durable way to sew wiring into your clothing, then puzzle no more: [Plusea] has put together a writeup detailing how to make a USB cable partly out of stretchy cotton fabric. Although the design as detailed doesn’t give much practical use for the invention, we can think of several very effective ways of exploiting this toy. Imagine, for example, placing a USB battery pack into one pocket of a jacket, a portable digital audio recorder in the other, and a lavalier microphone in the lining, thus enabling dozens of hours of covert audio surveillance.