9. Wearables¶

Welcome to another week of my Fabricademy journey.

The past few months have been incredibly rich with learning — though I’ll admit, balancing my need to explore within Fabricademy alongside everything happening in my life outside the program has been a challenge. But I asked for this, and I’m grateful for every moment of it.

This week is all about Wearables. Coming from an architectural background, I like to think of wearables as a kind of micro-architecture—a house for the body. This lens helps me explore what the body truly needs beyond the basic comfort of clothing. I don’t have the full answer yet, but I’m committed to discovering it through experimentation.

Since electronics is still very new to me, my approach this week focuses on three foundational swatches: Soft Speaker, Flip-Dot Actuation , Nitinol (Shape-Memory Alloy) Movement.

References & Inspiration¶

This week, I drew inspiration from three projects that expand the boundaries of what textiles and electronics can become. EJTech’s Folding Frequencies demonstrates how sound, material, and movement can merge into a poetic sensory interface, showing me how wearables can be both expressive and responsive. Their work goes beyond functional making and invites us to question perception itself. Irene Posch’s Embroidered Computer reveals the power of traditional craft as a platform for computation, proving that circuitry can be soft, stitched, and beautifully integrated into fabric. For this week’s assignment, I’m borrowing her approach to structure and connectivity, hoping to create self-folding fabric actuated by flip-dots—though we’ll see where the experimentation leads. And Jie Qi’s Self-Folding Origami opens up a world where materials transform themselves through embedded actuation. I’m especially intrigued by the idea of remotely influencing one object’s behavior through another, and how this relational movement can inspire new possibilities for wearable interaction.

Understanding Power Load an Driver¶

To begin this week’s assignment, I started by trying to understand power load and drivers. Each wearable output requires a different amount of current, as shown in the image below. Some components, like vibrating motors, only need around 60–90 mA. Others, like flip-dots or heating elements, can require 500 mA to over 1 A, which is much more than an Arduino pin can safely provide.

Slide from Emma Pareschi’s Wearables Lecture — Power Loads

An Arduino pin can only supply 20–40 mA. So when an output needs more power than the Arduino can give, we need a driver.

This is where the transistor comes in.

Slide from Emma Pareschi’s Wearables Lecture — Transistor

A transistor works like an electronic switch or gate:

The Arduino sends a tiny signal (safe, low current).

The transistor uses that signal to turn on a bigger power source (like a battery).

The output device gets the larger current it needs—without damaging the Arduino.

In short:

Power load = how much current the device needs Driver = the circuit that delivers that current safely Transistor = the “switch” that lets a small Arduino signal control a bigger power load

This makes it possible to control high-power components (like Nitinol, flip-dots, and heating elements) using small, low-power microcontrollers.

Making Soft Speaker¶

How does it work?¶

A soft speaker sends electricity through a fabric coil. When the coil interacts with a magnet, the fabric vibrates — and those vibrations become sound.

Electric signal → Coil on fabric → Vibrates with magnet → Sound

When designing a soft speaker, it’s important to consider factors like coil tightness, material choice, magnet size, and magnet placement, as highlighted in Lisa’s slide below.

Slide from Lisa Stark’s Wearables Lecture — Sound

Tools & Materials¶

Paper (I used baking paper because thinner, more flexible sheets tend to vibrate more easily and produce clearer sound — There’s still room for experimentation with different paper types to optimize sound quality.)
Conductive Copper Tape (for creating the coil trace)
Scissors or Craft Knife
Alligator Clips (for connecting the coil to the power source)
9V Battery or Small Amplifier/Battery Pack (to drive the coil)
Strong Neodymium Magnet (essential for generating sound)

Process and workflow¶

For this experiment, I wanted to prototype quickly, so I opted to use conductive tape on paper instead of sewing conductive thread. Even with this simpler approach, there were still plenty of trials and errors along the way.

💭 Conductive tape works well for quick prototypes, but using conductive thread on fabric can produce better results. Thread allows much tighter spacing and more coil turns within the same area, creating a stronger magnetic field.

1. Creating the Coil

I first created the coil using conductive tape on paper so I could prototype quickly.

Making a Spiral Coil with Conductive Tape and Baking Paper

2. Testing the Coil

At first, I assumed that a bigger coil would make a louder speaker. But after testing with my multimeter, I realized that my original coil (about 9 turns) had too much resistance for the circuit to drive effectively. I then reduced it to 5 turns, which brought the resistance down to around 40 ohms.

Testing the Coil

In Continuity (Beep) Mode, the multimeter will only beep when the resistance between points X and Y is very low (usually below 30–50 Ω), indicating that the circuit is connected.

💭 When I first checked the circuit, I used the multimeter’s beep mode and noticed it only beeped for short distances, not around the whole loop. I later learned that beep mode only works within a certain low-resistance range, so it couldn’t detect the full path. Switching to the resistance (Ω) mode gave me the correct reading.

3. Connecting to a Mono Amp + Audio Source

For this step, I followed Lisa’s diagram from the lecture, but I chose to use a PAM8403 3W+3W Wireless Bluetooth amplifier instead of the Adafruit 2.5W Mono Amp. This allowed me to skip the audio jack entirely and connect to the speaker wirelessly through Bluetooth.

Slide from Lisa Stark’s Wearables Lecture — Mono Amp Connection

Amplifier and Bluetooth Sound Source Connection

Result¶

Playing Music on a Paper Speaker

The audio plays at a very low volume, and I can only hear it when my ear is close to the paper speaker. This happens because the PAM8403 amplifier is designed for low-impedance speakers (4–8 Ω), but my coil measures ~40 Ω, which is far above that range. At 40 Ω, the amplifier delivers much less current, so the electromagnetic force is weak. In addition, the coil has relatively few turns with wide spacing, which further reduces the magnetic field strength and vibration amplitude.

Creating Flip Dot¶

How Does It Work?¶

An electromagnet is a magnet that you can turn on and off with electricity. When electric current flows through a coil of wire, it creates a magnetic field.

In a flip-dot, the hematite bead acts like a tiny magnet. When current runs through the coil, the electromagnetic field attracts or repels the bead depending on the direction of the current, causing it to flip back and forth.

Slide from Lisa Stark’s Wearables Lecture — Flip Dot

Tools & Materials¶

Enameled Copper Wire (for making the coil). I originally used 38 AWG — it was far too thin and had too much resistance for a strong electromagnetic field.
Hematite Bead
MOSFET (IRLB8721)
Diode (1N4001) – protects the circuit from back-EMF
Arduino Board
Cardboard or Fabric Backing
Conductive Tape
Jumper Wires
Alligator Clips
Sewing Needles & Thread (for mounting or integrating into textiles)

💭 Make sure your hematite bead is magnetic. I accidentally bought a non-magnetic bead at first and spent way too long trying to figure out why nothing was flipping 😅.

Process and Work Flow¶

Create the coil by wrapping the enameled wire around a form 50–200 times.
Secure the shape by wrapping the wire ends tightly around the loop.
Burn off the enamel coating using a soldering iron or lighter so the ends become conductive.
Stitch or embed the coil onto fabric, paper, or a crocheted base.
Solder the two wire ends to your circuit.
Sew the hematite bead into the center of the coil.
(Optional) I attached a string and paper clip, hoping the flip-dot would pull the string inward to create a self-folding effect — but this didn’t work (explained below).
Program the Arduino to turn the electromagnetic coil on and off. Below is the test code I used to pulse the coil once per second.
Connect the coil and MOSFET circuit to the Arduino

Concept¶

Reference: The Embroidered Computer by Irene Posch (left). Right: My concept exploration — attempting to create a self-folding effect actuated by a flip-dot mechanism (right).

Flip-Dot Driver Circuit (MOSFET + Coil Test Setup)

Code Example¶

//Make the coil flip up and down

int signal_pin = 3; //define the pin where the Arduino pin (signal) is connected

void setup() {

pinMode(signal_pin, OUTPUT); //define pin of the Led as an output
//pinMode(pin, OUTPUT);

//pinMode(pin, INPUT);
//pinMode(pin, INPUT_PULLUP);
}

void loop() {

digitalWrite(signal_pin, HIGH); //turn the coil on   
//digitalWrite(pin, HIGH/LOW);
//HIGH -> 5V
 //LOW -> 0V ground
   delay(1000);                 //wait 1000millisecond 
digitalWrite(signal_pin, LOW);  //turn off 
delay(1000);                 //wait 1000millisecond

}
```

Results¶

Four fabric-mounted coil samples comparing turn count and electrical resistance.

Flip-Dot Testing with 35 AWG Coil and a 9V Battery

Observations¶

The electromagnetic force was too weak or uneven. I was likely using wire that was too thin and had too much resistance (35AWG — .157mm Diameter), which limited the amount of current flowing through the coil. Even though I increased the number of turns, the high resistance prevented the coil from generating a strong magnetic field.

Shape-Memory Alloy¶

How does it work?¶

Slide from Lisa Stark’s Wearables Lecture — Shape Memory Alloys

Slide from Lisa Stark’s Wearables Lecture — SMA Wire Resistance & Current Reference Chart (0.006''–0.008'' Highlighted)

💭 You might want to pay attention to the SMA Wire Resistance & Current Reference Chart, I made another mistake of buying the wire with too thick of a diameter (.5mm or.0197") and too much resistance for 9V battery and it doesn't work.

Tools & Materials¶

Nitinol Shape Memory Wire (.006" is ideal — I bought .0197", which is too thick for a 9V battery to power)
MOSFET (IRLB8721)
Diode (1N4001) – protects the circuit from back-EMF
Arduino Board
Cardboard or Fabric Backing
Conductive Tape
Jumper Wires
Alligator Clips
Sewing Needles & Thread (for mounting or integrating into textiles)

Process and Workflow¶

Sew the SMA wire onto the fabric.
Connect it to your power source.
Optionally, connect it to an Arduino if you want to program or control the movement.

Note

Slide from Lisa Stark’s Wearables Lecture — Soldering SMA Wire

Concept¶

Concept Visualization: 3D-Printed Fabric Movement Driven by SMA Actuation — Pattaraporn (Porpla) Kittisapkajon

Code Example¶

// SMA / Heating Element Control (matches the video timing)

const int mosfetPin = 9;   // PWM pin connected to MOSFET gate

void setup() {
 pinMode(mosfetPin, OUTPUT);
 analogWrite(mosfetPin, 0);   // make sure it's off at start
}

void loop() {
 // Turn SMA ON (PWM = 250 ≈ 98% power)
 analogWrite(mosfetPin, 250);
 delay(1000);   // heat for 1 second

 // Turn SMA OFF
  analogWrite(mosfetPin, 0);

  // Wait 5 seconds before repeating
  delay(5000);
}

Results¶

SMA Wire Configuration Tests with Measured Resistances — Pattaraporn (Porpla) Kittisapkajon

Error: My 9V battery couldn’t drive the SMA wire, and I couldn’t find .006" SMA.