9. Wearables¶
Wearables¶
Photo by Svetlana Khachatryan
Research¶
I had been looking forward to the week of wearables. This week got a little personal for me. My curioity lays in creating thermo-wears. Why? I have what is called FMF (Familial Mediterranean Fever), which is an auto-inflammatory illness. When a person has an FMF attack, your abdominal organs get inflamed. Your muscles become tense and rigid. While blood flows to the inflamed area, the skin gets less blood flow and becomes cold, even though you may be running a fever. One of the most soothing things you can do during an attack is apply warmth to the abdomen. Sometimes attacks are mild and you have places to be and things to do. So I am wondering if I can make a body suit that you can wear and heat up parts of it. This is a no brainer, of course. Many companies do this. However, if i could learn how to make a thermo-wear myself, then I can design it specifically to fit my needs and my body.
References & Inspiration¶
My Clim8¶
Clim8 uses a smart, sensor driven thermal system, which measures the temperature of your skin, the environment around you, your activity level and heats up your clothing according to your data profile. You can control your wearables through their application via bluetooth. It uses a battery to power it, however the data analisys is flexible and you do not need to constantly regulate it. Due to its many sensors a processor that analyses the data, it only uses the battery when you are wearing it and when you need the heat. It will automatically go to sleep when heat application is no longer needed. Flexible conductive elements are used to turn power into heat.
Tools¶
- Copper wire
- 9V battery
- Permanent magnet
- Stainles steel conductive thread
- W1209 thermostat module
- aligator clips
- medium to light cotton fabric
- Instek GPD-3303D Triple-Output Linear D.C. Power Supply
Flipping Magnet¶
To make a flipping magnet you will need enough copper wire to wrap around a pen 50-100 times, with two ends stretched out. It is important to sand the ends of the wire and burn it with a lighter, to expose the metal and make it conductive.
Place your permanent magnet on top of the coil. Take two alligator clips and connect to a 9V battery. Connect one of the alligator clips already attached to the battery to one end of the copper wire. Carefully connect the other alligator clip to the other end of the copper wire.. once the circuit is closed your magnet should flip!
Making A Circuit¶
MOSFET Transistor¶
A MOSFET transistor is an electronic switch or amplifier. It has three gates - G (Gate), D (Drain), S (Source). When Voltage is applied to the Gate, it will create an electric field, which then will either open or close the path between Source and Drain. There are two types of MOSFETs. An N-channel MOSFET, which is what we will use, will conduct when a positive voltage passes through the gate. There are numerous MOSFETS and choosing the right one that will work with the Fabrixiao was a little hard to come by. The best MOSFET you can use with the Fabrixiao board RP 2040 is IRLB8721, however the closest one I could find was IRL3705. This is also an N-channel logic level with a Vgs min 1 - max 2.
Diode 1N4001¶
A 1N4001 diode is a commonly used diode, used for power and protection. In this case, it is used to protect the MOSFET from overheating and damage. It must be placed with the stripe (cathode) up.
Blink Code¶
After soldering the circuit according to Liza Stark's suggestion I realised that I do not have enough alligators to connect the Fabrixiao board to the GND and PIN, so I connected wires and soldered the wires to the board too. To make sure that everything was working I ran a blink test.
void setup() {
pinMode(8, OUTPUT);
}
void loop() {
digitalWrite(8, HIGH); // turn coil / embroidery ON
delay(1000); // 1 second
digitalWrite(8, LOW); // turn it OFF
delay(1000); // 1 second
}
Blink Test
After making the circuit, I was ready to test the code that Emma Pareschi provided to give the coil used in the flip magnet experiment. When the coil is placed over the magnet and connected to the circuit, powered by battery and coded with Arduino IDE through Fabrixiao board, it's supposed to move and stop then move again. This is achieved by using the Gate of the transistor. The pin will supply the Gate with 3.3V then 0V.
When I initially tried it, it didn't work, so I had to debug it by checking the voltage using the multimeter. I initially checked my battery to make sure that it has not died, it showed 8.9V. I checked the Gate of the transistor - which was going from 3V to 0V, showing me that the code is working. I checked the Load as well. Everything seemed to be connected fine and my alligators worked too. However my magnet was not attracting the coil.
Using multimeter to check if the Arduino IDE code is working
My coil is 3 Ohms and I have a 9V battery. If I use Ohm's law then I=V(9)/R(3) = 3 amperes. This could either mean that I need to make my coil thicker, aka longer to have more resistance, or use a smaller battery.
void setup() {
// put your setup code here, to run once:
pinMode(D8, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
digitalWrite(D8, HIGH); //=> 3.3V
delay(1000);
digitalWrite(D8, LOW); //=> 0V
delay(1000);
}
Experimenting Thermo Wear¶
I made coil embroidery using stainless steel conductive thread. I love working with conductive thread, as I do a lot of slow stitching and this feels just like that! To understand and experiment with thermo- wear, I decided to experiment with this coil, using a W1209 thermostat module with the help of Onik Babajanyan.
W1209 Thermostat Module¶
The thermostat module is a very straightforward module, that works with a 12V battery (or power supply). When you set a maximum and minimum temperature and connect the probe to the sensor interface, the relay will open when the temperature has not reached the set maximum and close once it does.
Conductive Thread¶
We connected one of the thread tails to the positive of the DC power supply using an alligator. We then connected the other tail to the negative of the W1209, and then from W1209 to the negative of the power supply. We then programmed for the W1209 thermostat module to allow temperatures to rise to 40C and turn off. The thermostat module comes with a temperature sensor, which we positioned on the embroidery to detect temperature changes.
Once all the connections were done and we supplied it with power, the embroidery started heating up! It was a slow rise in temperature. Something that felt controllable and safe.
Conductive Textile¶
Next, we experimented with the conductive textile coil. But this time we decided to really heat it up to see when the textile will melt and fall apart! Yes, our curiosity got the better of us.
At around 60C the material snapped!
Since I plan to make a heat pad that I will wear, it was interesting to see which material worked better. The conductive textile actually heated up much faster than the conductive thread. This was a very productive experiment for me.
Conductive Copper Tape¶
Next I did an experiment with conductive copper tape. Working with copper tape, insulated in a layer of felt would be fast and easy. I initially measured my body, then made a sketch using Adobe illustrator, to cut the copper tape with Roland.
The idea was to produce even heat distribution throughout the wearable piece. The copper tape would connect to the thermostat module and work with battery. However, when I made the connection the thermostat module started blinking would not display any temperature. We then directly connected the copper tape to the DC power supply, using alligators. Copper tape does not have much resistance. I had also made a 44cm long sketch, which meant that it produced a very big amount of ampers. This experiment tought me that, if I was to use copper tape then it would have to be small and a thin singulare wave. Not the best for the product I wanted to use it for, nor for even heat distribution.
Photos by Svetlana Khachatryan
What the DC Power Supply Display is showing is that essentially due to the lack of resistance, it is creating a short circuit.
R=V/I =0.01/3.10 ≈0.003 Ω
For further experiments with thermochromatic dyes, I will use conductive stainless steel thread.