Sewn open: Arduino and soft electronics

As several other recent threads on SemiWiki have pointed out, the term “wearables” is a bit amorphous right now. The most recognizable wearable endeavors so far are the smartwatch and fitness band, but these are far from the only categories of interest.

There is another area of wearable wonder beginning to get attention: clothing, which has drawn the interest of researchers, makers, and moms alike. The endgame as many see it is smart clothing: the weaving of electronics, sensors, and conventional fabrics into something called e-textiles. However, while athletes, soldiers, and other niches may get sensor-impregnated jerseys sooner, affordable clothing based on exotic advanced fabrics for most consumers may still be 20 or 30 years away by some estimates.

Right now, we have these anything-but-soft computing structures – chips, circuit boards, displays, switches – adaptable for some clothing applications. Still missing are some key elements, most notably power in the form of energy harvesting or smaller and denser batteries. The influence of water-based washing machines and their adverse effect on most electronics also looms large.

How do we cross this gap? It’s not all about advanced R&D; these types of challenges are well suited for experimentation and the imagination of makers. Several Arduino-compatible maker modules – all based on Atmel microcontrollers – have jumped in to the fray, showing how “soft electronics” can help create solutions.

photo courtesy Becky Stern

Maybe I’ve built one or two too many harness assemblies using expensive, mil-spec circular connectors, but the fascinating thing to me is what makes all these boards wearable. Small size is nice, but anybody knows a project needs wiring, right? You’ll notice the large plated holes on the first several offerings: these are eyelets for conductive thread, literally intended to sew these boards to other components like fabric pushbuttons. Many projects also use snaps, similar to 9V battery connections, to disconnect boards for conventional washing of the garment.

The other side of this is the software. One of the attractive features of Arduino is the IDE, real live C-style programming simplified for the masses, with functions designed to perform I/O on the Atmel MCU. Code is edited on a PC or Mac, and compiled into a sketch and uploaded to the board. There are so many examples of code for Arduino maker modules out there available in open source, it makes it easy to find and integrate functions quickly.

If that all sounds crazy, consider the pioneer for this is Leah Buechley of the MIT Media Lab, one of the thought leaders of the maker movement and an expert on e-textiles. She is the brain behind the LilyPad, the original 2” diameter Arduino wearable circa 2007 commercialized through SparkFun, with the most recent version featuring the ATmega32u4 and native USB.

Adafruit took the next steps with two wearable boards. FLORA is slightly smaller than the LilyPad and retains the same familiar circular profile and ATmega32u4 MCU. GEMMA goes even smaller, 1.1” in diameter, packing an ATtiny85 on board with a USB connection for easy development.

Not to be outdone by circles, squares and rectangles have recently come back into form. SquareWear 2.0 comes in two versions, the 1.7” square variant with a coin cell socket onboard, both including the ATmega328 MCU with simulated USB, high current MOSFET ports, a light sensor, and a temperature sensor. Seeed grabbed the ATmega32u4 and designed it into the Xadow, a tiny 1” x 0.8” expandable unit with integrated flat cable connectors for daisy chaining.

These aren’t just toys for creating flashing LEDs; there is no shortage of sensors and connectivity, including displays, GPS, Bluetooth, and more compatible with these wearable maker modules. Their popularity is growing: Becky Stern of Adafruit claims there are over 10,000 units of FLORA shipped so far, and they are the darlings of maker faire fashion shows and hackathons.

Besides the upside for makers, maybe this sewing angle will finally allow us to explain electronics to our moms, after all. Until we get to the fulfilled flexible future of e-textiles and more advanced technology, the conductive thread of soft electronics will stitch together creative ideas using somewhat familiar tiny modules with today’s microcontrollers.

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