MIT Makes Washable LED Fabric

Let’s face it, one of the challenges of wearable electronics is that people are filthy. Anything you wear is going to get dirty. If it touches you, it is going to get sweat and oil and who knows what else? And on the other side it’s going to get spills and dirt and all sorts of things we don’t want to think about on it. For regular clothes, that’s not a problem, you just pop them in the washer, but you can’t say the same for wearable electronics. Now researchers at MIT have embedded diodes like LEDs and photodetectors, into a soft fabric that is washable.

Traditionally, fibers start as a larger preform that is drawn into the fiber while heated. The researchers added tiny diodes and very tiny copper wires to the preform. As the preform is drawn, the fiber’s polymer keeps the solid materials connected and in the center. The polymer protects the electronics from water and the team was able to successfully launder fabric made with these fibers ten times.

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Prestretched Fabric Prints Pop into the Third Dimension

Printing on fabric might be a familiar trick, but adding stretch into the equation gives our fabric prints the ability to reconstitute themselves back into 3D. That’s exactly what [Gabe] has accomplished; he’s developed a script that takes open 3d meshes and converts them to a hexagonal pattern that, when 3D-printed on a stretched fabric, lets them pop into 3D upon relaxing the fabric.

[Gabe’s] algorithm first runs an open 3D surface through the “Boundary-First Flattening Algorithm,” which gives [Gabe] a 2D mesh of triangles. Triangles are then mapped to hexagons based on size, which produces a landscape of 2D hexagons. Simply printing this hexagonal pattern onto prestretched fabric defines the shape of the object that will surface when the fabric is allowed to relax. As for how to wrap our heads around the mapping algorithm, as [Gabe] explains it, “The areas that experienced the most shrinkage in the flattening process should experience the least shrinkage when the fabric contracts after printing, and the regions that experienced little to no shrinkage in the flattening process should contract as much as possible in the fabric representation.”

If that seems tricky to visualize, just imagine taking a cheap halloween mask and trying to crush it flat onto a table. To smush it perfectly flat, some sections need to stretch while others need to shrink. Once flat though, we can simply keep stretching to remove all the sections that needed to shrink. At this point, if our material were extremely elastic, we could simply let go and watch our rubber mask jump back into 3D. That’s the secret behind [Gabe’s] hexagonal pattern. The size and spacing of these hexagons limit the degree to which local regions of the fabric are allowed to contract. In our rubber mask example, the sections that we stretched out the furthest have the most to travel, so they should contract as much as possible, while the sections that shrank in the initial flattening (although we kept stretching until they too needed to stretch) should shrink the least.

We’ve seen some classy fabric-printing tricks in the past. If you’re hungry for more 3D printing on fabric, have a look at [David Shorey’s] flexible fabric designs.

Thanks for the tip, [Amy]!

Mechanisms: Hook and Loop Fasteners

As a species, we’ve done a pretty good job at inventing some useful devices. But as clever as we think we are, given sufficient time, natural selection will beat us at our game at almost every turn. So it makes sense that many of our best inventions are inspired by nature and the myriad ways life finds to get DNA from one generation to the next.

Hook and loop fasteners are one such design cribbed from nature, and the story behind this useful mechanism is a perfect example that a prepared mind, good observation skills, and a heck of a lot of perseverance are what it takes to bring one of Mother Nature’s designs to market.

Editor’s Note: As some predicted in the comments section, we were contacted by representatives of Velcro Companies and asked to change all mentions in this article to either VELCRO® Brand Fastener or to use the generic “Hook and Loop” term. If it seems weird that we’re calling this hook and loop, now you know why.

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Capacitive And Resistive Touch Sensors For Wearables

When you look at switching solutions for electronic wearables, your options are limited. With a clever application of conductive fabric and thread, you can cobble together a simple switch, but the vast array of switch solutions is much more than that. This one is different. The zPatch from [Paul Strohmeier], [Jarrod Knibbe], [Sebastian Boring], and [Kasper Hornæk] at the Human-Centred Computing Section at the University of Copenhagen gives eTextiles capacitive and resistive input. It’s a force sensor, a pressure sensor, and a switch, all made completely out of fabric.

The design of this fabric touch sensor is based around a non-woven resistive fabric made by Eeonyx. This fabric is piezo-resistive when compressed. This material is sandwiched between two layers of silver-plated polyamide fabric, which is then connected to the analog input of a microcontroller. On top of all this is a polyester mesh, with everything held together with iron-on sheets.

Reading this sensor with a microcontroller is extremely similar to a capacitive touch sensor made out of copper and FR4. All the code is available in a repo, and all the materials to reproduce this work can be found in the various links provided by the team. That last point — reproducibility — is huge for an academic work. Not only did the team manage to come up with something interesting, they actually provided enough documentation to reproduce their build.

In the video below, you can see how this sensor can be used to sense a hand hovering, a light touch, a hard press, or anything in between. Only two analog pins are required for each sensor, making the routing and layout of this eTextile should be relatively easy to integrate into clothing. It’s a great build, and we can’t wait to see the community pick up on these really cool sensors.

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You’ve Never Seen A Flipping Eyeball Like This One!

Inspired by some impressive work on textile flip-bit displays, and with creative steampunk outfits to create for Christmas, [Richard Sewell] had the idea for a flippable magnetic eye in the manner of a flip-dot display. These devices are bistable mechanical displays in which a magnet is suspended above a coil of wire, and “flipped” in orientation under the influence of a magnetic field from the coil.

In [Richard]’s case the eyeball was provided by a magnetic bead with a suitable paint job, and the coil was a hand-wound affair with some extremely neat lacing to keep it all in place. The coil requires about 200 mA to ensure the eye flips, and the job of driving it is performed by a Digispark ATTiny85 board with an LM293 dual H-bridge driver upon which the two bridges are wired in parallel. The whole is mounted in the centre of a charity shop brooch that has been heat-treated to give a suitable aesthetic.

You can see the eyeball in all its glory in the two videos below the break, and should you be curious you can also read our write-up of the original pieces from [Irene Posch] that inspired it.

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The Latest 3D Printed Fad: Flexible Armor And Pangolin Cosplay

Last week, [David Shorey] came along to the monthly Hackaday meetup in Pasadena. These meetups feature speakers and drinks, projects and chit-chat, and sometimes a few demos of what the local Hackaday community has been working on. [David]’s impromptu demo was something no one had ever seen before. It’s 3D printed tiles embedded in fabric. This is the beginning of 3D printed flexible armor, a great method for cosplay builds, and a really cool way to add another trick to your 3D printing toolkit.

Hexagons tesselate. Image credit: DrainSmith

The steps to reproduce this project are actually very easy. The most important bit is the fabric itself. This is just a piece of tulle, a fine fabric mesh that’s usually used for bridal veils. According to members of the 3D printing community, you can pick up some tulle in the fabric department of any WalMart. The steps to reproduce this technique are simply to print three layers, pause the print and move the head out of the way, lay the tulle down on the print, and hit resume.

Judging from the commentary surrounding this new technique, there are a few tips and tricks to get the most out of this 3D printable fabric. The fabric should be taut and held down with either tape or binder clips. Melting or burning doesn’t seem to be an issue, but tulle made out of nylon is fairly common, and printing 3D panels with exotic filaments that require high temperatures may result in a mess.

While very cool, there are some limitations to the technique. If, for example, you are building a suit of body armor out of bendable tessallatable panels, you will have to assemble a quilt made out of panels as large as your print bed. This could be made easier by sewing (or gluing) the tulle/scale assembly onto a larger piece of fabric. Alternatively, the process could be modified for use with an Infinite Build Volume printer. This would give you yards and yards of 3D printed scales, ready to be fashioned into an outfit.

This is one of the most interesting techniques to bring 3D printing into the domain of ‘soft’ hacks and fashion we’ve ever seen. If you want to check out what’s possible with this, be sure to follow [David] on Twitter and out his Instagram. There are a lot of really great ideas there.

As with most ideas in 3D printing, this is one that’s been done before, albeit at not such a high level. [Drato] a.k.a. [RobotMama] did pretty much the same thing a few months ago, and we thank her for her contribution to the community.

3D Printing Wearables with a Net

If you want to build wearables, you need to know how to sew, right? Maybe not. While we’re sure it would come in handy, [Drato] (also known as [RobotMama]) shows how she prints designs directly on a net-like fabric. You can see a video of the process below.

The video after the break shows an Ultimaker, but there’s really nothing particularly special about the printer. The trick is to print a few layers, pause, and then insert the fabric under the printer before resuming the print.

[Drato] holds the fabric down after inserting it, and mentions you can use glue to hold it down, too. We wondered if some bulldog or alligator clips might work. The only thing we worried about is if the fabric were made of some synthetic, it might not take hot plastic without melting.

[Drato] mentions she uses Organza, which is a sheer fabric often found on wedding gowns. However, she doesn’t mention if she is using the polyester, silk, or nylon type of the fabric. A little research shows that polyester and nylon fabrics melt at about 295 C. Silk was harder to track down, but since you can iron it on a medium setting, that might work, too. Of course, the temperature where it melts and the temperature where it just deforms beyond use might be different, so some experimentation is probably wise.

What really piqued our interest was the application to creating wearables without sewing. We’ll be curious what other applications you could find for printing directly on a fabric substrate.

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