Why spend time etching circuit boards and applying solder masks when all you really need is a rollerball pen and some paper? That’s what University of Illinois professors [Jennifer Lewis and Jennifer Bernhard] were asking when they set off to research the possibility of putting conductive ink into a standard rollerball pen.

The product of their research is a silver nanoparticle-based ink that remains liquid while inside a pen, but dries on contact once it is applied to a porous surface such as paper. Once dry, the ink can be used to conduct electricity just like a copper trace on a circuit board, making on the fly circuit building a breeze.

Previous ink-based circuit construction was typically done using inkjet printers or airbrushing, so removing the extra hardware from the process is a huge step forward. The team even has some news for those people that think the writable ink won’t hold up in the long run. The ink is surprisingly quite resilient to physical manipulation, and they found that it took folding the paper substrate several thousand times before their ink pathways started to fail.

While we know this is no substitute for a nicely etched board, it would be pretty cool to prototype a simple circuit just by drawing out the connections on a piece of paper – we can’t wait to see this come to market.

If you’re into embedded clothing this stroke sensor is for you. As demonstrated in the video after the break, stroking the threads in a particular direction will create a circuit that senses and, in this case, turns on an LED. The concept uses two conductive buses on the back of a piece of neoprene. Conductive and non-conductive threads are then  added for a furry or bristly finish. When stroked perpendicular to the power buses the conductive threads come together and form a circuit.

For some reason this just seems a bit creepy to us but perhaps that’s only because we haven’t come up with the right application for the technology. We’re pretty sure that a sweatshirt with an LED marquee and a “hairy” back that you stroke to illuminate is the wrong application.

The chill of autumn is upon us, and with it comes the awkward sport of trying to work touch-sensitive phones and gadgets with gloved fingers. One can try toughing it out with fingerless gloves, or we’ve seen some costly solutions in the forms of specialized gloves and capacitive-compatible styluses, but sometimes simple is best: all it takes is a few stitches of conductive thread in the fingertips.

Conductive thread is available from various sources; SparkFun Electronics comes naturally to mind, but most vendors carrying the LilyPad Arduino will stock a suitable thread as well. Don’t fret if you’ve never sewn before — just a few simple loops are required, and it doesn’t need to be especially tidy. In principle this should work for trackpads and capacitive mice as well, if you use those in the field. For multitouch devices, add a separate conductive bit to each fingertip.

[via Lifehacker]

(Thanks to [Aaron] for the tip) As a promo for [Calvin Harris], some of the creative minds at Sony Music have put together an Arduino-based sythesizer composed of 15 bikini clad babes. By analyzing which circuits are closed, the Arduino Mega is able to tell a sequencer which sample to play. The only innovation happens to be that the circuits are painted onto the aforementioned girls with a conductive body paint known as Bare.

Developed by students at the Royal College of Art, the paint is not available for purchase, but they are willing to mix a batch up for art installations or performances. Technical stats (such as resistance) have not been released, but for a washable paint it seems to be performing quite well.

How was the whole project set up? The video below reveals all:

The recent announcement of Psyclone’s TouchCharge kit has us moderately excited. Though inductive charging has been used in electric toothbrushes for ages, we have yet to see it infiltrate the rest of our lives. The kit is a bit pricey at the moment, but it is a step in the right direction. Unfortunately, you have to have an adapter for your specific product and their selection is pretty limited right now. Why not make your own to power your devices?  Warning: it is written from the perspective of [Arnold Schwarzanegger].

Update: Is the TouchCharge kit inductive? It appears to require contacts to touch the base.