Hola, SIGGRAPH! or How to do an e-textiles workshop for 50 people

I was invited to give a workshop with my knitted sensors on August 2nd at SIGGRAPH 2017, a huge computer graphics conference in Los Angeles.  It went great-- everyone's knitted sensors were up and running in just over an hour! 

Hands-on workshops require a lot of planning. People progress at different rates and can get impatient waiting for each other or for assistance. Too much waiting and the workshop loses momentum.  

So I like to work with small groups. I move around to offer assistance, and encourage people to help themselves to materials and progress at their own rate.

This wasn't going to work at SIGGRAPH-- the classroom was spread out with no middle aisle. And I'd be wearing a body mic. If I walked in front of the speakers, I'd set off ear-piercing feedback (which I did, twice, oops...). Plus... I wanted to give people sleeves that fit their hands but there was no way to measure hand sizes of participants ahead of time.

So we had to get creative with solutions.


Dylan responds to a post-it note call for help.

There wasn't room for participants to get their own materials, and asking for help would slow the presentation down. So I gave everyone bright yellow post-it notes. If they needed something, they wrote it on the post-it, attached it to top of their computer monitor, and one of our volunteers would sprint over to read the note and help or retrieve materials.  Worked great!


Ziploc full of goodies

Materials were distributed to each workstation in baggies, in advance, thanks to workshop coordinator Brittany Ransom. Plus, we put a pdf of the powerpoint presentation on each computer's desktop (see below). I invited people to use it to progress at their own rate.
 
Sewing diagrams

I tested out the activity with the volunteers ahead of time, and realized that tech people were going to struggle with sewing the wires in place. They needed sewing diagrams! Luckily I had time to add a few. We didn't have to worry too much about the knot because we had Fraycheck-- a fabric glue. And glue makes sewing seem easy!

I also made diagrams on Fritzing for the breadboard connections--super helpful.

Fits like a glove

Instead of sizing participants, everyone randomly received either a 10x30 or 12x40 size-sleeve on it (with the size labelled). I figured this would get the right size into the hands of at least half the attendees. I invited people to swap with their neighbors or flag us down to request another size. (I also brought 10x40 and 12x50 sized sleeves.) I was surprised to find that only a few people requested another size.

The one thing we didn't pass out in advance was the resistors. In order to get the best range from your sensor, it's important to match it with an appropriate fixed resistor. But the resistance of the sleeve depends on how it fits the wearer.  So I had everyone measure their sleeve resistance and write it on a post-it. The volunteers picked up the post-its, and passed out appropriate resistors.

In preparation, I had taped the resistor packs onto a large cardboard backing with the values labelled. During the workshop, it was easy for the volunteers to grab the exact resistor they needed to "fill the order" on each post-it.

 
Materials for Knitted Finger Sleeves
Resistive yarn (80% polyester, 20% stainless steel)
Snaps #199 10 Line (6.9 mm), nickel finish
Striveday silicone coated stranded wire AWG 26
Male crimp pins  these are great for breadboarding
tapestry needle
yarn for sewing wire
Dritz Fraycheck

Also used:
Breadboards
Hookup wire
Arduino uno
piezo discs
resistors
multimeters
scissors

My tools (used to knit the sleeves ahead of time and attach wire with snaps)
Superba Knitting Machine
Snap Press Machine (with punch/die)
Crimp tool (I use Engineer Inc PA-09 crimping pliers )

img: Tesia Kosmalski


Improving Arduino sensor range



Adding a fixed resistor ½ the value of a variable resistance sensor improves Arduino performance.


Whenever you connect a 2-lead variable resistor (VR) sensor (like a photo cell or bend sensor) to an Arduino, you add a resistor to it. I did this with my knitted stretch sensor. It creates a circuit known as a voltage divider, which controls the voltage level, based on the relative resistance of the resistor to the sensor. This is important because the voltage level is what AnalogRead "reads" in Arduino.

I wondered what value would give the best performance for my knitted sensors. So I used the equation below to calculate the output range of voltage dividers, based on the ratio between R1 and R2, given that R2 is my knitted sensor and R1 is the (unchanging) resistor. I graphed the outputs for each VR value at 0%, 25%, 50%, 75%, and 100% of its maximum range.

Recipe for Student Feedback (homemade, from scratch)


My advanced class made spring reverb units this semester. Steve and Connor stacked theirs together with a homemade tone control and a hefty dose of feedback.


Ian attached his contact mic to a jar for a duet with his sequencer. He also installed his entire rig in an old stage monitor case.


Trevor, Andy, and Brian, plus some really sweet synth.


Daniel, Rachel, Robert, and the joy of three sequencers on one clock.

Finger Sleeve Sensors

I made these knitted sleeves from a conductive yarn that changes resistance as the knit is stretched.

Jenna Boyles, Kyle Werle, and Christine Shallenberg beta-tested the sensors at Pumping Station: One. They selected sleeves for fit, then stitched on the wires themselves. Kyle and Christine were able to use the sensors to control an analog synth and a processing sketch.


Knitted Finger Sensor from Jesse Seay on Vimeo.


With this project, I wanted to design a glove that could be machine-knit for workshops cheaply and quickly, making a wearable bend sensor available to people with no textile skills.

I decided to go with a modular approach (individual sleeves instead of single glove) because:

  • gloves are not easy to knit by machine
  • fit is important, as the tightness of the knit impacts the resistance. The tighter it is, the lower the resistance.
  • there is no one-size-fits-all with gloves. individuals with the same hand width might have very differently-sized digits

With a range of sleeve sizes, users can select the sleeve with the best fit and resistance range for each digit. We attach flexible silicone wires by means of a snap press, and the wearer then sews the wire in place with a tapestry needle and yarn -- very easy!  Transferring the sewing to the end-user means I can produce a batch of these more quickly for a workshop. Once the sleeve is finished, the user can use the tapestry needle to easily sew the wire leads in place along a fingerless glove.

Resistance varies by user. Everyone could reduce the resistance to less than 100 Ohms by curling up their finger. We were generally able to get a maximum resistance of at least 5k with a tight fit, to 20k or 30k for a more comfortable fit. The shorter the sleeve, the lower the highest possible resistance. Longer sleeves had much more range.

The sleeves are knit on a Super S48 double bed machine. Both beds are at tension 10, with a bed gap of 4. The sleeves are circular knit, with cast on/cast off using waste yarn, then finished by hand stitching. The sleeves should cover most of the finger, but are not intended to cover the fingertips.

Sizing:

Sizing has been a challenge with this project and it took some experimenting to get a useful range of sizes. For workshops, I need to be able to knit sleeves of the appropriate size ahead of time, based on a single hand measurement submitted by a participant.

I tested the sleeves for fit and resistance on a dozen volunteers at Pumping Station: One. From that, I created a sizing chart, in order to offer a range of sizes, based on hand circumference.

Wear-a-Circuit Workshop

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Circuit Patches are wearable circuit boards made from knitted yarn and wire. I'm doing a workshop Sunday using these. Check it out!

I use a knitting machine to make the patches, and add snap buttons with a snap press. Now the circuits can be attached to anything-- no sewing required.

Rapid prototyping for Wearables!

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I made these circuit patches for my upcoming workshop. Participants will receive a 3" x 5.5" knitted proto-boards in black, pink, or teal. Solder LEDs and a battery on it, and you can add lights to your clothes, just in time for Halloween.

Of course, there's lots of things beyond LEDs you could add, and I'm hoping to do workshops for interactive circuits using knitted protoboards soon.

I've made a number of circuits with this method so far, usually in black. For this workshop, we're adding some fun color: circuit-board-teal and... pink! I  couldn't resist adding 10mm gumdrop LEDs to the pink protoboard pictured above.

We'll have some of those jumbo LEDs for the workshop, but also smaller ones in blue, yellow, red, white. I've even got some color-change and flicker LEDs.

If you'd like to participate, please RSVP. Hope to see you Sunday! (Bring a shirt or a hat or a bag so you can add snaps to mount your circuit on it.)

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My new favorite machine: the snap press applies snap buttons without sewing.

Snapshots from Japan

I spent a month in Japan this summer. Here are things I want to remember and places I want to return to.  Read on for contemporary art, textiles, craft, electronics and a makerspace. 

Simple LED tricks

I created these circuits for Chicago Art Department's Crystal Ball Fundraiser Auction. The top two bidders will receive their choice of design as a custom fit cuff bracelet.

Candle flicker LEDs are an easy way to add movement to your lights, without a microcontroller.
Wire the flickering LED in parallel with non-flicker LEDs and they will alternate flickering. Make sure the different LEDs have similar forward voltages, otherwise some might not light up at all.



Slow-Fade RGB LEDs offer another easy trick, cycling through a rainbow of colors. It looks very cool set off by single color LEDs. If you limit the current enough with a high resistor, some of the LEDs will go dim at different points in the cycle.




With the above circuit, I slipped a piece of resistive velostat under the battery contact, as a dimmer. Without it, all 3 LEDs remain on, continuously.






Passap Knitting at Pumping Station: One

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Aushra knits on the Passap

2015 was the year of the Donated Double Bed: two Passap Duomatics and a Superba S48. I had no experience with either brand, so it's taken awhile to get one working and online. There was cleaning and repair (tag-teamed with Dan, Erica, and Will), designing and building a worktable (thank you, Shae!), followed by the scavenger hunt for missing parts (props, Katrin and Richard!).

But I'm pleased to report it's finally happening! At a recent "Knitting Machine Office Hours" at Pumping Station: One, we tested settings that work with the Passap using fingering weight Tamm 3-ply Astracryl yarn. And we figured out how to knit from cones (no cake winding required)! Read on for a complete step-by-step.

Felting Yarn

I first knitted with Yeoman Felting Wool last summer, when Yeoman donated a large box of yarn to the eTextiles Summer Camp. It's easier to hand-felt than other wool yarns I've tried, so I ordered a half dozen colors and started to play. It's fun to make detailed colorful designs, and perfect for holiday gifts. But there are a few pitfalls in creating your design. Read on for info about:
  • holes between colors
  • uneven felting due to pattern and color
  • felting technique
Holes

The designs pictured are "single motif": the pattern does not repeat and the contrast yarn stitches are wider than 5 stitches in a row. This results in long "floats" of yarn on the back side. Normally you'd "wrap" the edge needles while you knit to avoid big gaps caused by the edge stitches "laddering." Instructions for this are often included in machine manuals under "how to knit single motif". 
The edge needles are not wrapped in this piece. This resulted in laddering: large gaps and sagging stitches at the edge of each color. This is particularly visible around the brown in the middle.