Lab 6: WovenSkin

June 23, 2022

Tools and Materials

TinyLily Kit
Loom (20 slots or 10 e.p.i)
Cotton yarn (Recommended: 20 warp threads, 6.5 yards of thread)
Acrylic yarn (chunkier than cotton)
Conductive thread
Scissors
Comb
Multimeter (how to use)

TinyLily Kit

Purl & Loop Minute Weaver Loom

Thin Cotton Yarn

Thin Conductive Thread

Multimeter

Acrylic yarn

Loom

Comb

Needle

Introduction to WEAVE

Woven fabric is formed by interlacing warp yarns and weft yarns, which run in perpendicular directions. The warp yarns are vertical, and held under tension on a loom, while weft yarns are horizontal and pass between warp yarns.

First, try setting up the loom using the chunky acrylic yarn we have provided (the thickest yarn on the spool). Follow the instructions below to get familiar with weaving a plain weave.

Set up for weft

Measure out 6.5 yards of thread (we’ve measured it for you).
Pull your yarn through the whole in your “tapestry needle”. Your kit does not come with a tapestry needle, but you can tape the yarn to anything long and thin (ex. A paintbrush or toothpick). Leave a 3-4 inch tail. This is what we will use to weave the yarn between the warp threads.

Plain Weave

Plain weave is considered the most basic weaving structure. In plain-woven fabric, each weft yarn goes over one warp yarn and under the next. This "over, under" sequence is repeated. Neighboring weft yarns pass through warp yarns in alternating sequences to secure the structure.

Goal:

Start by following the instructions below to weave your first plain weave. Use the thicker acrylic yarn for this practice weave. You have an extra fine 20 slot loom, but you will only be using every other slot for the warp with this chunky yarn, so that you have 10 warp threads.

Construction Steps

You will be constructing a basic plain weave with conductive thread to program using Arduino!

**Click to Enlarge Purl & Loop Instructions below

Purl & Loop Set Up

Purl & Loop Instructions

Purl & Loop Weaving

Fabrication & Weaving

Process Pictures:

1. Set up loom warp with thin yarn. The one used in this tutorial is 20 warp threads, 6.5 yards of thread.

2. Start with a plain weave and weave about a third of the way up.

Note: It may be easier to have tails of the threads on alternating sides of the weft yarn so it is easier to hook up to the TinyLily Mini Processor (tails for conductive threads should stay on the same side for easier programming)

3. Cut off the yarn. Cut ~1.5 yards of conductive thread. Weave this continuously until you have at least a 0.5cm section of conductive thread.

4. Continue to plain weave with your yarn, weaving a 0.5cm section.

5. Repeat steps 3 and 4, two more times so that you have 3 evenly spaced sections of conductive thread the center of the weave.

6. Continue to plain weave until the loom is filled.

7. Finish your weave and remove it from the loom using steps 10-15 from pictures provided in the Purl & Loop tutorial. Feel free to reference videos.

Set up your loom

Weave 1/3 with cotton thread

Weave ≤.5 cm Conductive Thread

3 sections of Conductive Thread

Functionality

Set Up TinyLily with Arduino

Download Arduino and use this link for TinyLilyProcessor with Arduino for more details .

Program Your TinyLily

1. Connect your TinyLily to the computer

2. Launch the Arduino IDE and navigate to the Tools tab. For the TinyLily Mini Processor, we are going to make the following selections:

Board: "Arduino Pro or Pro Mini"
Processor: "ATmega328p (3.3V, 8MHz)"
Port: "COM##" - this is the port connected to the TinyLily via the MicroUSB cable (for Mac find “dev/cu.usbserial XXX”)

3. Upload the Captouch code we have provided for this tutorial to the TinyLily:

Download Code

4. Connect the weave to the LilyTiny:

Conductive threads SHOULD NOT touch, cross or intersect each other
Make sure that the fraying from the ends of the conductive thread do not interfere with the processor or other conductive threads

5. Attach each conductive thread to pins A0, 2, and 3 by tying them to the holes in the TinyLily.

6. Observe the changing values in the serial monitor when you touch the conductive areas of your weave!

Observe the values changing with every touch!!

(Optional) Other Weaving Patterns to Try

(Optional) Inserting different materials in weft and/or warp

What other materials can we insert in the weft?
- Colored thread
- Thermochromic thread

Reflection Questions

How would you compare the capacitive touch slider you created here with the DuoSkin capacitive touch electrode in Lab 3?
Which step did you find most challenging in this lab?

For your Lab 5 submission, construct a woven slider (5.2). Post a photo onto the Canvas discussion board, with a 100-word description on what you made, responses to the reflection questions, and any challenges you encountered on the way.

Note: if you are already an experienced electronics builder you are encouraged to expand the project to match your skillset.

FAQ (Frequently Asked Questions)

Q1. Between conductive thread and copper wire, which one would be more conductive and reliable?

Answer: Copper wire would be more conductive and often more reliable than conductive thread.

Q2. After weaving the conductive threads in the Tiny loom, in total 6 thread ends remain loose. Which ones get connected to which holes?

Answer: You have to connect three different conductive thread sections to three different pins of the TinyLily MCU. That means you can select one loose thread from each section and tie them to the assigned holes in the TinyLily. In our example, the TinyLily pins are A0, 2, and 3 respectively.

This is quite similar to Lab 3. In Lab 3, we made one capacitive sensing section with the gold metal and here we are making three capacitive sensing sections with three sections of woven conductive fabric.

Lab 5: Skin Sew

June 23, 2022

Tools and Materials

36 Gauge Conductive Wire
Embroidery Hoop 6- inch
TinyLily starter Kit, incl. Mini Processor Board, USB Board, RGB LED, Battery Adaptor, Battery, needle, micro-USB cable
Temporary tattoo paper pack
PVA roll, Sulky (embroidery stabilizer)
Scissors
Sandpaper
Sponge or Tissues
Multimeter (How to use)

36 Gague Conductive Wire

Embroidery Hoop 6 inch

TinyLily Kit

Temporary Tattoo Paper Pack

PVA Sulky

Multimeter

Construction Steps

Fabrication

It may be helpful to follow this video tutorial of the entire process:

1. Construct the “SkinCloth” skin overlay substrate (this is described in Fig 2. In the SkinWire paper). Set to dry.

The three types of layer you will be using:
a. Green sheet: temp tattoo adhesive (packed together with the white sheet)
b. White sheet: temp tattoo silicone
c. Transparent sheet: PVA (Sulky, embroidery stabilizer)
The image bellow illustrates the three layers of SkinCloth

remove backing from adhesive

Stick adhesive on sheet, remove bubble

2. Apply adhesive sheet on temp tattoo sheet

3. Remove the green backing from the adhesive layer

4. Stick that on temp tattoo sheet on the smooth and glossy silicon side of the white sheet.

5. Remove bubbles

Diagram of application

6. Cut a piece of the PVA roll to fit the tattoo sheet. You can feel the PVA and observe that is has a smooth side and a rougher side. Set aside for now.

7. Remove the clear cover of adhesive paper. After you remove the adhesive, one side of will be papery, while the other is sticky.

8. Stick the glossy (smooth) side of PVA onto the sticky side of the white sheet. So now one side is matte PVA and one side is paper.

It is recommended to put the PVA on the table first with the glossy side up, then gently place the white sheet with the sticky side facing down.

9. Remove paper part of temporary tattoo sheet by applying water

Soak the paper side with a wet paper towel/tissue or sponge (make sure not to apply TOO MUCH water!). The left picture below looks about right.
You can also tap it with your finger. Peel off the paper layer slowly and carefully. See the picture below right.

10. Wait for it to dry.

Peel off paper layer

SkinCloth created!

FUNCTIONALITY

Construct TinyLily RGB LED Circuit

Detailed tutorial from TinyLily webpage. There are many ways the RGB LED can be connected in your project. For simplicity sake, we used the alligator clips here. Regardless of the method you choose, use the following steps to build your circuit.

Arrangement Diagram

Diagram with Alligator Clips

1. Follow the Diagram for constructing the circuit:

Be careful if you follow the image, numbers are flipped. Make sure that you connect to pin 1 not θ1.

2. First, connect ground from your processor board to the RGB LED marked with (-).

3. Connect the voltage lines marked by (+).

4. Finally, connect your desired IO pin to the IN tab on the LED.

Software Setup

1. Download and install the FastLED Library: For this tutorial, you will need to download the FastLED Arduino Library zip folder, and then install it as a library in your Arduino (For first timers, here are steps to install an Arduino library here).

The FastLED Arduino Library provides compatibility with many different types of RGB LEDs as well as a great deal of predefined color palettes and example code.
(Note that these are WS2812B RGB LEDs and this will have to be specified in any code you use with this library. Reference the code below to see how this is done.)

2. Upload Main Arduino Program to LilyTiny Microcontroller :

Download your main Arduino code via the link below, compile and upload to your TinyLily microcontroller:

#include <FastLED.h>
#define NUM_LEDS 1 //this is the number of LEDs in your strip
#define DATA_PIN 1 //this is the number on the silkscreen you want to use
#define COLOR_ORDER RGB

CRGB leds[NUM_LEDS];

int brightness = 20; //value from 0-255 to manipulate brightness

void setup() {
  FastLED.addLeds<WS2812B, DATA_PIN>(leds, NUM_LEDS);
  FastLED.setBrightness(brightness);
}

void loop() {
  for (int i = 0; i < 256; i++) {
    fill_rainbow(leds, NUM_LEDS, i, 256 / NUM_LEDS);
    FastLED.show(); //update the LEDs
    delay(100); //optional delay for slower fading
  }
}

Download Code

The program should blend your LED(s) through the colors of the rainbow. If you're interested in creating other lighting effects, check out the example sketches included with the library. It is likely you'll have to change the defined number of LEDs, type of LED, and data pin.

IMPORTANT: if the LED is only lighting in green, that means there is an issue.

3. Once your Arduino code has been successfully uploaded into the LilyTiny microcontroller, you should see the LED lighting up and go through the colors of the rainbow!

4. Replace the programmer with TinyLily Battery Adapter and power with the battery in the tiny lily kit (so it can be standalone and no longer connected to laptop).

LED should light up after code is uploaded

Replace the adaptor with a battery

Tip: If you are getting errors when uploading, It may be helpful to remove the alligator clips from the TinyLily microcontroller when uploading the Arduino code. Here is a link for troubleshooting with compiling/uploading your Arduino code to the LilyTiny Microcontroller.

SkinCloth Application

1. Plan out where you would like to place this circuit on the mannequin hand and sketch out the circuit layout on a piece of paper.

2. Place SkinCloth in the embroidery hoop. Once the SkinCloth is dry, place it into the embroidery hoop for the next steps of sewing.

IMPORTANT: The temporary tattoo silicone side (slippery side) should be facing up.

3. Based on your plan of the circuit in Step 1, use a pencil or pen to sketch out the placement of the components on the SkinCloth.

Place SkinCloth in Embroidery hoop

Transfer Circuit to SkinCloth

4. Sew and complete your circuit on the SkinCloth with the 36 gauge conductive wire. Note that the conductive wire is insulated!

IMPORTANT: Remember to sand down the ends of the wire to connect it to the leads (we need to do this since the wire is insulted!). One tip is to adhere down the TilyLily components to the SkinCloth to prevent it from moving around when sewing.

IMPORTANT: Remember to use the bronze conductive copper wire (36 gauge) for this step (NOT the silver conductive thread!)

5. Once you are done sewing, attach the battery and see the RGB LED shine!!

Demo video on skin cloth:

SewSkin Application

Remove from the embroidery hoop, apply a layer of temporary tattoo adhesive (green sheet) underneath the skincloth, and apply on the mannequin. It may help to apply multiple layers of the temporary tattoo adhesive.

Cut SewSkin into desired shape

Apply a layer of tattoo adhesive

Apply on skin!

Demo video of final working prototype: https://drive.google.com/file/d/1upzkGojUDirwy5CInS8_ggMpdSeCnlZa/view?usp=sharing

Reflection Questions

How would you compare the SewSkin fabrication process with DuoSkin? Could you use DuoSkin instead of SewSkin to complete this lab?
What body locations do you think SewSkin is uniquely suited for?
Which part of the fabrication process did you find most challenging?

For your Lab 2 submission, construct your SewSkin RGB LED circuit. Post a photo of each onto the Canvas discussion board, with a 100-word description on what you made, responses to the reflection questions, and any challenges you encountered on the way.

Note: if you are already an experienced electronics builder you are encouraged to expand the project to match your skillset.

FAQ (Frequently Asked Questions)

Q1: What are some common prototyping materials that can be used to connect circuit components as an alternative to copper wire?

Answer: Conductive thread, conductive tape, alligator clips, conductive ink, etc.

Q2: What is the avrdude: stk500_recv() error, and how to resolve the issue?

Answer: Check connections. Try to unplug and replug the wires or restart the Arduino to redo the uploading.

Lab 4: DuoSkin Touch Sensor

June 23, 2022

Tools and Materials

LilyTinyKit
Gold metal leaf
Spray Adhesive
Conductive Fabric Tape
Metal leaf Sealer
Exacto knife
Paintbrush
Foam brush
Tweezers
Sponge
Multimeter (how to use)
Laptop
Arduino IDE (downloaded and installed)
USB adapter (in case your mac has a C port.
*Pre-cut temporary tattoo paper with vinyl cut in cap touch electrode shape
Silhouette America Tattoo Paper (if you are designing your own)

TinyLily Kit

USB Adapter

Conductive Tape

Spray Adhesive

Gold Metal Leaf

Metal Leaf Sealer

Multimeter

Electrode Shapes

* If constructing DuoSkin Touch Sensor without pre-cut temporary tattoo paper, you will need to design your own.

Construction Steps

***If you are using a pre-cut temporary tattoo paper with vinyl circuit stencil, skip steps 1-10

Design & Vinyl Prep

1. Use a vector rendering program to create desired tattoo design (example: Adobe Illustrator)

Make sure there is a complete path of reasonable conductivity for the traces (minimum 2-3mm)

2. Export design as .dxf so that it can be opened by the Silhouette Studio application. Adjust size and placement of design on grid schematic provided.

3. Use a piece of Silouette America Tattoo Paper that is a considerable amount larger than your tattoo. Cut a piece of Con-Tact vinyl adhesive slightly larger than your tattoo paper.

4. Remove a edge of the Con-Tact vinyl backing and line up the vinyl, sticky side down, with the shiny side of the tattoo paper, with a bit of the Con-Tact Paper hanging over the edge.

5. Slowly apply the vinyl onto the tattoo paper as you peel off the backing, smoothing out the vinyl so that there are minimal air bubbles.

6. Using the excess Con-Tact around the edges of the tattoo paper, create a secure bond between the tattoo sheet and the Silhouette America Light Tack Cutting Mat.

Be sure to align the sheet with the grid on the cutting mat, which corresponds to the grid visible in the Silhouette Studio software. Put the Con-Tact side up.

7. Turn the Silhouette America Cameo Electronic Cutting Machine on and insert the cutting mat by selecting “load mat” on the LCD Touchscreen.

Make sure the black arrow on the cutting mat is aligned with the center black ring on the machine and that the mat is loaded in straight.

8. Via USB, connect your computer with the Silhouette Studio Application open to the cutting machine.

9. Adjust Cut Settings in the menu provided on the right hand side of the application window. Set “Cut Style for Selected Shape” to “Cut Edge” and set “Material Type” to “Vinyl.”

This will allow the blade of the machine to cut the design through the layer of Con-Tact paper but only graze the tattoo paper below.

10. Select “Send to Silhouette” in the bottom right corner of the application window to begin cutting.

Make sure there is a complete path of reasonable conductivity for the traces (minimum 2-3mm)

FABRICATION

Adding Gold Leaf

1. Now that the Con-Tact paper is cut, use a tweezer to remove the positive space of the design from the tattoo paper (where you want the gold foil to adhere).

It may be helpful to trim the tattoo paper before executing this step to allow finer control while peeling the Con-Tact paper (and the gold leaf later on).

2. Spray the sheet with a light layer of the Metal Leaf Spray Adhesive. Spray from about 12-15inches away in a sweeping to ensure even coverage.

Don’t spray too much glue! A thin layer is important.

3. Wait approximately 30 seconds for the adhesive to get tacky. Place the tattoo paper, glue-side down, onto a sheet of gold foil, press down, and then carefully peel foil off of its backing.

4. Dab a soft high density sponge (foundation sponge) to reinforce the bond between the foil and the paper.

Extra pressure should be applied around the edges of the design.

5. Repeat the previous three steps for the desired number of gold leaf layers (usually 2-4).

Peel Vinyl

1. To make the peeling process easier, make small cuts at the corners of the NFC tag (using an exacto knife or sissors) to make it easier to remove the contact film layer

2. Using tweezers, carefully peel off the vinyl, leaving only the parts of the tattoo you want on the paper.

Go slowly, keep your tweezers close to the paper, and pull parallel to the edge you’re peeling the vinyl off of.
Be extra careful around sharp turns and corners!

NOTE: Do NOT yet seal in your design, you will need to ensure conductivity after conductive fabric tape is applied!