November 25, 2019 · Lab work

E-Textiles Testing and Lab Work

As my final project is going to involve textile work, along with sensitive touching, I thought I would build a small textiles project to test my skills with conductive thread and conductive fabric amongst other things. I decided to make a set of bracelets, that when held held across each other would cause an LED to light up. I imagined this kind of like a super-hero or magical girl transformation, where one strikes a pose to gain more power.

she-ra grabbing her sword
She-Ra and the Princess of Power

I started by wiring up the first bracelet, with an LED at the top of the bracelet, and then two strands of conductive thread running down the insides, one for power, and one for ground. I terminated the thread with pieces of conductive fabric to make the connection between bracelets later easier to make. To test that my connections worked, I connected power and ground on respective sides of the first bracelet.I used my Adafruit Metro to provide 3.3v of power, removing the need for a resistor.

After confirming that the first bracelet worked, I moved on to threading the second bracelet with conductive thread and 4 pieces of conductive fabric, two in the middle and two at the ends. This would be the bracelet that the battery/power would be connected to in this project. I then proceeded to test the second bracelet, connecting the power and ground to it's end pieces, and then laying the first bracelet atop the second to see if the connection between the two was working.

After establishing that the bracelets worked when the connections were made between the conductive fabric on the inside of each one, I put them on to demonstrate how it would work when worn:

Wrists apart, no power to LED

Wrists together, LED lights up

Although a messy prototype, I think that I demonstrated the basic function of these bracelets well. My main take away from this project was that conductive thread can be difficult to work with. It's quite fiddly and easy to get connections touching each other which should be separated. Keeping the ground line and power line separate in my circuit was a challenge, and had to be mitigated by routing the connections down the sides of the bracelets.

Below are two fritzing diagrams, one containing the prototype built with the Metro providing power, and a hypothetical diagram with a coin cell battery which would be placed into a holder sewn onto the bracelet without the LED.

Diagram showing circuit powered by the Adafruit Metro

Diagram showing circuit powered by a coin cell battery

In conclusion, I think adding textiles with touch sensors (and even capacitive) into my final project is an achievable task, but I need to neaten up my sewing skills in order to produce a more polished and product.