Hello from Boulder!

My blog has been pretty quiet lately and for good reason! I’ve recently relocated to Boulder, Colorado to join the Education Department at SparkFun Electronics. I’ll still be updating the blog with my personal projects, but to keep up to date on all the fun stuff I am making and teaching (including updates from our National Tour) please visit the SparkFun Education site.

– Angela


My Hoops at Maker Faire

Here are a couple of detail pictures and videos of the hoop prototypes I brought to Maker Faire. I’ll have a longer post later in the week with all the cool stuff I saw and played with while wandering around the faire grounds. I wasn’t able to shoot great video at the faire because of the noise, so the two I included were shot in my hotel room (hooping indoors is quite a challenge!). I’m hoping to bring these pieces to a hoop jam and have some other hoop dancers try them out soon.



I mostly wore the sound making outfit around during the weekend, as my light up one was hard to see anywhere but inside the darkened Fiesta Hall. It was fun to wander through the crowds and do mini demos along the way. This is a slight variation on the beatbox hoop prototype I blogged about previously – instead of a hacked toy I used a LilyPad Arduino to make notes for each of the conductive patches. Many thanks to my fellow Seacoast Maker Alex Nunn for helping me with some last minute code on this one before I left for the faire. The nice thing about this particular jacket is that the board is completely modular; sewing snaps allow you to remove the LilyPad from the traces and speaker and pop in another one in the same configuration. I also used Sugru to add a finishing touch and a little extra protection to the connection between the snaps and the wires going to the LilyPad. I stopped by the Sugru booth and they loved the use of their product in wearables.



The first prototype is a little messy with some hot glue to make sure things didn’t fall apart with all the movement. The outfits held up well after two days of hooping, with only minor repairs needed.



I modded some gloves with conductive patches so that I could create effects while hooping on my hands as well. They snapped right into the sleeves of the jacket.

This is a completed version of my early experiment with LEDs. A small battery holder, conductive fabric, and LEDs make it a nice blink and bling example of my hoop-as-a-switch concept.




This little battery holder from Aniomagic worked well on the collar of this jacket. Unfortunately, it looks like they don’t make them anymore.

Hula Hoop Experiments

This summer I fell in love with hoop dancing and have been brainstorming fun ways to combine hooping and soft circuits.

Most of us have seen the fancy LED and fire hoops that make for great performances, but can it be taken a step further and have truly interactive hoops? Here are a few projects I’ve found that bring hooping to a whole new level. At the end of the post I’ve included documentation of some of my own early prototypes.

Lighting/Visual Effects

Uber Hoop

Christian Miller created the Uber Hoop – “The world’s most technologically advanced hula hoop! Features fully controllable RGB LEDs, a MEMS accelerometer and gyroscope, an embedded Arduino, and Bluetooth for wireless communication. The result is a hoop that responds to your motions and dazzles with beautiful light patterns!”

Fiber Optic Hoops

I’ve seen a lot of LED hoops, but fiber optic lighting is a fun twist. This one isn’t interactive, but still captivating to watch.

Controllers – Media and Music

Hula Rhythm

HoopElastic Sensor
This project concept from the Interaction Lab at Holon Institute of Technology utilizes an elastic preassure sensor on the body to register the rotation/pressure of an ordinary hula hoop and translates it into a musical game.

Hip Disc

Hip Disc
The Hip Disc uses conductive fabric on the edge of two hoop-like discs to trigger music. Not quite hooping, but it is an interesting new way of controlling music with your body.

Musical Hula Hoop – Fact or Fiction?

HOOLA 2.0 Demonstration from shmermans on Vimeo.

Hooping.org has a great article on the future of sound making/controlling hula hoops.

Anossens: The Game and The Reality

I really like this use of a hula hoop as part of an interactive game/live show created using Processing and webcams.

Data Logging

Smart Hula Hoop

Smart Hula HoopSmart Hula Hoop
The Smart Hula Hoop, created by a team of students from National Yunlin University of Science and Technology, uses an iNEMO board to “to transform the standard hula hoop into a complete healthcare sports monitor system. They did this by accessing and fusing together output data provided to the iNEMO by its on-board accelerometer (measures gravity and acceleration), e-Compass (measures absolute heading orientation), and gyroscope (measures angular velocity during exercise.)”

My Prototypes

I’m particularly interested in POV toys and if they can be successfully installed on a hoop in a seamless way. I’ve been talking with Instructables author Quasiben (who made a nice and simple Arduino POV) about creating a hoop that you can send text to through a smartphone and change the graphics on the fly. The video below is my first test to see if the hoop rotation was fast enough to display the text properly. Next step is to get the hardware into/on the hoop in a more permanent, clean way (right now it is just taped on the surface).

POV Hoop Test #1 from Angela M. Sheehan on Vimeo.

My other experiments have been playing with the idea of the hoop itself being a trigger, with most of the electronic components residing mostly on a garment. This solves the problem of bulky tech in such a small space. I’ve glued some conductive fabric tape on the inside of one of my hoops and have then been using patches of conductive fabric on various shirts as contact points. When hooping across these areas, the hoop acts as a switch.

Hula Hoop Switch – Test #1 from Angela M. Sheehan on Vimeo.

Beatbox Hoop Mock Up Test#1 from Angela M. Sheehan on Vimeo.

Many hoop dancers use music with their performances, so what if you were able to create the music based on your movement? I’m experimenting with a beatbox drum machine toy to see if I can get some interesting flow happening. I’ll be bringing my prototypes to the Hoopium hoop jams to talk with more advanced hoopers about placement of electronics and feedback. Stay tuned!


Summer Vacation

After a whirlwind month of two maker faires – the Cambridge Mini Maker Faire and the Bay Area Maker Faire, I am ready to take a brief vacation from blogging. I’ll be working on a few projects throughout the summer and I hope to share them along the way or when I start blogging more often in the fall. See you then and enjoy your summer!

Here are a few pics from my trip to San Mateo for Maker Faire.

I had a great time doing a demo at the CRAFT booth on getting started with soft circuits. I had some examples of conductive threads, fabrics, and kits to show and pass around.

I met up with Dia, Sparkfun’s TechStyle Specialist, who had a cool sound-making dress with conductive flower petals and conductive threads as the triggers.

I got to stop by the Instructables HQ in San Francisco, so exciting! We made some liquid nitrogen ice cream and got a tour of the office.


Crochet Sensor Experiments

Here are a few tests of crochet stretch sensors (and some more knit sensors for comparison) as I try to determine the method that works best for me. I did a few experiments with crocheted vs knit sensors, conductive yarn vs conductive thread, and felted vs non-felted, and using elastic thread to see how each variation of the sensor would compare to the others.

I made a felted crochet stretch sensor following Felted Signal Processing’s Instructable – their method uses elastic thread to help add stretch and regular conductive thread along with wool yarn.

It was a little tricky keeping track of 3 strands while crocheting, and you can see from some of my pictures that I dropped a few stitches in places. I could only find the elastic thread in 11 yard spools, and these sensors (between 11″ and 15″) took about two spools each to complete. This type of sensor took more time and materials than the spool knit samples I made, but had a nice solid feel to it.

I was interested to see how felting the conductive yarn and knitted sensors would compare with the original sensor trials I had done, so I made a few more with variations. Here are the sensors before felting (from top to bottom):
A: Knitted sensor on 3 pin Wonder Knitter w/ elastic thread, wool yarn, and conductive yarn
B: Knitted sensor on 6 pin Wonder Knitter w/ elastic thread, wool yarn, and conductive yarn
C: Crochet sensor w/ elastic thread, wool yarn, and conductive yarn
D: Crochet sensor w/ elastic thread, wool yarn, and conductive thread

Here’s a side by side comparison of a felted sensor and the others ready for felting.

And all the finished sensors.

So how did they compare? Here is a chart of my results:

Sensor Resting
A 15″ 2.5 M ohm 20″ 12 K ohm
12.5″ >20 M ohm 14.5″ 3 M ohm
B 17″ 3.3 M ohm 22.5″ 4 K ohm
13″ >20 M ohm 15″ 2 M ohm
C 11.5″ 2.8 K ohm 13″ 1.2 K ohm
10″ 1.7 M ohm 13″ 1.3 M ohm
D 11″ 20 ohm 13″ 15 ohm
9.5″ 38.5 ohm 11″ 35 ohm

The crochet sensors, while nice and sturdy, weren’t really all that stretchy. I also noticed that they didn’t bounce back, and over time would stretch longer and longer. Maybe a different type of elastic would help with this issue.

The conductive thread sensors also need to be very long in order to get a large range of values, so I think the knit sensors with conductive yarn will be the way to go for hooking up to a drawdio.

Making Knit Stretch Sensors

This week my order of Nm 10/3 Conductive Yarn from Plug and Wear arrived. I immediately started making some samples of the knit sensors I blogged about a few weeks ago.

Following Hannah Perner-Wilson’s tutorial/method, I made two sensors using a Wonder Knitter from the craft store. It came with two attachments, a 3 pin and a 6 pin to make a thinner and thicker knit tube.

After making two knitted sensors with a combo of acrylic yarn and conductive yarn, I made my own knitting spool out of an old thread spool and some nails. I used some sock weight yarn in a similar thickness to the conductive yarn and made a nice thin sensor.

Here are the three sensors I made side by side. They are about 15 inches long with tails to connect the conductive yarn to alligator clips for testing.

Resistance readings from my multimeter:

  • Sensor C: 6 pin knit on Wonder Knitter – Resting 4.45 M ohm, Stretched: 10 K ohm
  • Sensor B: 3 pin knit on Wonder Knitter – Resting: 3.9 M ohm, Stretched: 10 K ohm
  • Sensor A: 3 pin custom spool knitter and sock weight yarn – Resting: 1.0 M ohm, Stretched: 10 K ohm

After doing some more tests, I’m going to start prototyping a knit version of my Musical Drawdio Puppetusing the sensors as the tentacles so that you can ‘play’ it by pulling on them.

I’ve also been teaching myself to crochet and will be trying out more techniques soon. I made a crochet button using the example on How To Get What You Want.

Hooking the sensors up to an LED to control brightness:

Project: Anglerfish Theremin Plush

Awhile back I purchased a couple of Gakken Mini Theremins to play with. They are the perfect size to embed into stuffed toys (the magazine that came with the kit even has an example with a plush dog toy). Around the time that I was getting ready to head to the World Maker Faire, I had the idea to use one of these mini theremins and put it into an anglerfish puppet – the bendy antenna would be the perfect size for the fish’s lure. I originally started making a fish out of fleece but found it was hard to hold it’s shape. I put the project on hold while I got everything ready for the faire and it got ignored for awhile.

In the past few weeks I have been teaching myself to crochet and making some amigurumi critters. I was looking online for some new patterns to try and remembered my anglerfish project – why not try and crochet one? Since I couldn’t find a pattern to follow I decided to make up my own version. While a little cartoony, I’m happy with the result.

Once I had a basic fish, I prepped the mini theremin to go inside. I ditched the red case the circuit board came in and replaced the AA batteries with AAA in a holder with an on/off switch.

I also replaced the antenna with a sturdier one from an RC car. The final touch was adding an LED for the anglerfish’s lure and as a power indicator.

Once everything was hooked up I put the board in a small plastic box to protect it, and threaded the LED and antenna into the plush’s antenna. I found that if the wires from the LED were too close to the antenna wire it would cause interference, so I ended up attaching them along the outside and covering them with a whip stitch.

Everything went into a pouch inside the fish to keep it from getting tangled in the polyfil I used to stuff it. Velcro along the edge makes for easy access to the battery pack to turn it on/off.

Packed up and ready to play! So far, the antenna isn’t very sensitive so you have to be right up close to the fish to get any change in the sound. I had the same problem when the theremin was set up as a kit before hacking it, and am looking for a way to get a better range. There are some potentiometers on the board for adjusting and I saw something about using tin foil to ground it through the battery pack, so I’ll try a bit more and see if I can some better sounds out of it. If I get some good results, my next step is to add an audio jack to hook it up to an amp, and maybe turn the eyes into knobs for on-the-fly adjustments.

Sound Projects Month

To show support for my friends currently doing the RPM Challenge (writing and recording an album in 28 days), I’m going to spend February focusing on sound-making and musical projects. Here are some inspirational projects, tutorials, and products to get some ideas flowing. I already have a few toys ready to hack and build into soft plush instruments and wearables; I’ll start posting updates on what I come up with next week.

Soundie: A Musical Touch-Sensitive Hoodie

This tutorial shows you how to make a hoodie that generates different tones based on conductivity – kind of like a Drawdio but using a LilyPad.

Soft Circuit Musical Tie

A tie created by using the soft synthesizer example from the Open Softwear ebook [via Make: Online]

DJ Hoodie

This project from Kobakant has some great behind the scenes photos and documentation.


A really cool portable noisemaker. I love the way that it unfolds and snaps together to play.

Square Band

The Square Band is a portable square wave synthesizer. The Square Band is worn around the wrist like a watch and includes a set of eight buttons to trigger tones of varying octaves. Additionally, a light sensor is used to change the pitch of the tone within the octave allowing for a wide range of musical possibilities.


The Thingamakit from Bleep Labs built into a hat. [via Make: Online]

Clothtylophone – Cross Stitch Stylophone

Cool cross stitched stylophone using LilyPads and conductive thread. [via Make: Online]

Knit and Crochet Sensors

One of my goals for 2011 is to learn to knit and crochet. I love the look of handmade yarn projects, and lately have been seeing more and more using soft circuits. I’m particularly interested in projects that incorporate conductive yarns into the work, rather than adorning or augmenting the piece with conductive threads or electronics.

Here are a few techniques I’m hoping to try once I get the hang of some needlework basics.


Circular Knit Stretch Sensor

Hannah Perner-Wilson shows you how to make a sensor using conductive yarn on a knitting machine that you can purchase at craft stores.

Stretch Sensing Bracelet

Another technique from Hannah uses conductive and resistive yarns to make a bracelet that only lights up when you stretch it.


Felted Crochet Stretch Sensor

Lara of Felted Signal Processing has a tutoral on crocheting and then felting a stretch sensor using yarn and conductive thread. If you work better following along with a video, check out her tutorial here. This technique is a good alternative if you can’t acquire and conductive yarns for the knitting sensor tutorials.

Crochet Tilt Potentiometer

Crochet Pressure Sensor

How To Get What You Want has examples of combining conductive yarn and regular yarn to make potentiometers, tilt, and pressure sensors.

Ready Made

Plug and Wear Sensitive Fabrics

Plug and Wear is manufacturing a variety of etextile sensors, including pressure sensors, stretch sensors, and even water/wetness sensors.

Conductive Core Yarn

Aniomagic sells a handspun yarn with conductive thread inside. Just cut the yarn and expose the thread to hook up components in your soft circuit project.

Knit Sensors on Etsy

Hannah Perner Wilson also has an etsy shop where you can buy some pre-made knit sensors, as the conductive yarn to make them can be expensive and hard to find in small quantities.