Notes from the Lab 8/08

Currently I am working on a project where I have been sewing a circuit into a hat (which is the style of the old aviator hats). It has a felt outer shell and an inner lining made of linen. My intention for this project was to have the circuitry covered by the felt layer and all of the circuits sewn into the linen layer, with the LEDs popping out into the felt layer. Felt is a great fabric to work with because you can make holes in it and it will not fray.

Ian Hanschen drafted out this circuit using the software Circuit Wizard, which is a great way to run a simulation of a circuit if you don't feel like setting it up on a bread board. The circuit is a LED flasher with 8 LEDs. 4 flash on one side of the hat and the other 4 flash on the other side.

I sewed the traces using my sewing machine (with conductive thread in the bobbin) and attached all of the components by hand. What I have discovered is that conductive thread actually contains a great deal of resistance. I am measuring about 80 ohms for every 10 inches of thread.

Here is the originally sewn hat with all of the traces sewn on with a machine.




This will definitley impact how many ohms my resistors may have to be and how long I run my "traces".

When the thread is sewn by hand, I double the thread, creating a bundle, which decreases my resistance by half. I began replacing the traces I had sewn hand stitched lines.



The other issue I seam to be running into is when the hat lays flat the circuit seems to work, but when it flexes, I loose connections. I believe this is because the connections between the thread and the components are not strong enough. Each time the hat is flexed the joint between the components and thread is articulating too much, causing it to short. I've also noticed that when I bring 2 traces together, I am also not making good contacts. Below is an example.


Back in the lab...shooting trouble, until I remedy these issues.

Later...

PROTOTYPE

Thanks to REACTIVEfashion on Instructables for their ideas on how to do this...

Below is my first experiment with sewing with conductive thread, building a simple circuit in a fabric and making a switch from conductive Velcro.

Conductive thread is available from a number of suppliers and the spool I used was from Sparkfun Electronics and is a two-ply thread.

To use conductive thread in a sewing machine, I suggest putting the thread in the bobbin. If conductive thread is used in the needle thread, the tension of the stitch tends to loop and it becomes messy on either face of the fabric. Wind the bobbin as you would any other on your machine. If the conductive thread comes on a cone larger than your machine is capable of holding, just firmly hold it on a flat surface, at the base of the cone, and wind the bobbin as normal.

Next, I stitched, with conductive thread, two parallel lines: one, which was the ground and the other positive. I left about an about inch in between the two lines. I also marked the fabric, with a pen, closest to the positive side to remind me which line was positive. At the end of the positive line I stitched the male piece of some Velcro (aka the hook side).

After I sewed these two lines, I was careful to leave long thread tails to attach components or to securing to other lines that might be needed to complete the circuit.






Since the bobbin thread typically faces the back side of the fabric when sewing a straight stitch, I had to be conscious that the right side of the fabric would be the reverse of any regular sewing project. So, I went ahead and marked the front and the back of this prototype too.

Crimp the leads on the LEDs for attaching to fabric with thread. For LEDs that have long leads, it’s easy to crimp the leads around a needle nose pliers. All you have to do is bend the leads so that they are at 90-degree angles from the LED, and then, simply crimp the leads into little beads on either side. If you are using surface mount LEDs, SMD, you will have to solder small metal crimp rings to the anode and cathode sides of the LEDs. Here is the before and after.





Also, VERY IMPORTANT, mark the leads that are positive with a permanent marker or nail polish because when the leads are bent into beads, you wont’ be able to tell which side is the anode or the cathode.

A note about LEDs: If you are going to use different colors, make sure you use the proper resistors because some LEDs will eat up the juice of your circuit. You can always use the LED resistor calculator website if you are unsure. http://www.ledcalc.com/

Next, I attached the LEDs by hand sewing them to the positive and negative lines of the circuit. When tacking by hand, I first took a small stitch over the machine-sewn line, and then crossed over it again, to make sure that the initial hand stitch was making contact with the sewn lines.

Then, I securely attached the LEDs. In the photo below, I am attaching the LEDs to the positive side first. Quadruple tight tacks allowed the contacts to remain secure. Then, I sewed individual lines from the ground line to the other side of the LEDs.




The form, I created with this simple prototype, is a tube, which, required the Velcro switch to be on the front and the back. So as you can see (pls look below) the hook part of the switch is on the front and loop side of the Velcro is on the back.




I hooked up a 3.7V lithium ion rechargeable battery (approximately 2cm X 1cm X .5cm) and closed the Velcro switch and voila! Let there be light!

Textiles and Electronics

My interest in electronics and textiles started about 8 years ago. As a student at the University of Washington, I attended a lecture by Marie O'Mahony, who had been invited by the Electrical Engineering Department, to speak about her work. I was a student in the Fiber Arts and Sculpture program and the bridge between textile and technology intrigued me (and it still does today). (At the time I had been experimenting with the BASIC Stamp and tinkering with music boxes and putting them in soft objects). The body of work she presented consisted of garments, with the wiring attached to them, which kinetically moved them into different forms. For example, she created a series of dresses and skirts in which the hems on them were raised using a series of circuits.

O’Mahony’s innovation was making garments kinetically move without the physical interaction of either the human wearing it or another individual using physical force to alter it. The work was presented in conjunction with her book "Techno Textiles". However, the technology used in these pieces, was awkward and distracting. Furthermore, it worked against the functionality of the pieces. The power supplies on the garments were large, heavy battery packs and they were not attached to the human forms or the garments. Rather, they lay at the side of the model, which only allowed the model stationary movements. The wiring was boldly exposed and it made the viewer wonder if this was the desired aesthetic or simply a sacrifice for the new kinetic movements. Despite these formal functional distractions, the work was still a breakthrough in wearable technology.

Wearable technology and computers will soon be commonplace. How our clothes technologically behave, along with aesthetical appearance, will factor in to how we choose what we want to wear.

Clothing is an extension of ourselves and plays a key role in how view ourselves and how others view us within the culture we operate in. Culturally speaking, clothing is a marker. It communicates an individual’s class, sex, economic status, mood, and subculture within a society.

And one can’t help but draw a conclusion between “e-textiles” and our culture’s interest in the cyborg.

The conceptualization and contemporary imagery of the cyborg is probably rooted in the past. It is possible that we first conceived of the image of a cyborg, in its infancy, when we began using prosthetics in medicine. The development of imagery of the cyborg assumed solid shapes, because those shapes were the most physically functional. Imagery and artistry of the cyborg, in the past, has typically assumed that the additions of computers and electronics would be in solid materials. The chip, attached to the board, was always a solid material with little fluidity. And wiring, of any complexity, had to be baked with solder onto a PCB.

What if we could make circuits fluid and flexible? What if we allowed the form of circuits to follow the body or the shape of the garment or textile?

Let's make the case for conductive thread. It is flexible, can be stitched or woven into a textile or garment. With a little ingenuity, we can also eliminate the need for solder. Most importantly, it eliminates the PCB. It allows the garment and the textile to maintain its form, drape and fall freely. By stitching/weaving into the garment we can produce a freely flowing circuit board.

Let’s make the case for conductive inks that can be silkscreened onto fabric. Silkscreening is already used in a variety of applications on PCBs. So, why not silk screen directly onto fabric and add electrical components to it? A screen, with a breadboard like grid, could be printed onto fabric. Individuals, or possibly the wearers themselves, could attach components and be the designers of their own electrical circuits. And this would allow one to interact and change the appearance of a garment.

Please explore the links below. Have fun! We’re just beginning…

Vincent Leclerc with XS LABS

Be sure to check out the SKORPIONS project on this page!

MIT Media's lab on wearables.

Leah Buechley
Leah Buechley is a researcher that studies soft circuits specifically. She has tons of info for all experience and level types (novice to hacker) plus lots of good links for materials and kits.

SparkLab

Fashioning Technology

The work of Anouk Wipprecht

Fashion designer and artist Hussein Chalayan.

Joo Yoon Paek

New Brave World - Hybrid Scrapyard

PHOTOS

PHOTO: ANNA BARTELS CIRCUIT: ANNA BARTELS
Gimme Baby Robots Show, Portland and Milwaulkee

PHOTO: ANNA BARTELS
LED MATRIX: IAN HANSCHEN