Week 12: Skin electronics

This week's assignment was to use skin electronics to create a carnival mask with neopixels. As I was uncertain about putting electric circuits directly on my skin, I decided to make a mask from material with the neopixels, microcontroller and external batteries. To download the files, visit: https://oscircularfashion.herokuapp.com/project/-L6SX_pAbREawjWZ3ju8

Firstly as a group, we explored creating circuits on the skin with Bare Conductive ink. We used Adriana's pre-designed circuit and cut this cut as a stencil in the vinyl cutter using heat transfer vinyl.

We put the stencil on the skin and used the conductive ink to fill in the traces. We waited for the ink to dry before peeling off the stencil. However, when peeling off the stencil, the some of the ink stuck to the stencil and therefore didn't paste onto the skin. We tried to salvage this as much as possible by using water to help detach the ink from the stencil.

Once the stencil was fully off, we measured the conductivity with the multimeter. Because the ink tended to crack when it was dry on the skin, the connection was disrupted and thus did not conduct. However, the conductivity was fine in places where it was not cracked.

I wanted to create a masquerade mask rather than design one from scratch, therefore I searched on Google for images that I liked. I found the image below which I vectorised using Photoshop.

I put the image in Rhino to tidy up the design and create space for the neopixels above the eyes and for the microcontroller on the left hand side. I also created slots on the sides for the strap be fitted.

I then laser cut the mask in fake leather, using these settings for the big Epilog laser cutter: Speed 100, power 45, frequency 50.

Going back to the design in Rhino, I wanted to create traces with conductive ink and to do this, I had to create a stencil. Therefore on a different layer in Rhino, I created the components and placed them where I wanted, to act as a guide. For the battery, I planned to use a battery holder that would be attached to the strap, therefore I did not include this in the design.

In another layer, I then created the traces joining up the GND and VCC of all the neopixels to the corresponding legs of the microcontroller, and the Vin and Vout of the neopixels - making sure that they were not continuous connections like the GND and VCC.

I then created a stencil out of the traces and used the Silhouette program to prepare it for cutting in the plotter cutter.

In Silhouette, I chose A4 for the page size and cutting mat, and portrait orientation. I had to make sure the size of the design was correct therefore I measured the design in Rhino and specified this in Silhouette in inches as the program deals only with inches.

To prepare the design for cutting, I selected the 'Send' tab and specified my material (glossy vinyl) and the 'cut' action. The program prepared the cutting details and advised me to change the cutting tool depth to 1 - which I did using the mechanism on the plotter cutter machine. I then selected 'Test' to see if the cut was ok.

After a successful test, I sent the design to be cut in the plotter using glossy transfer vinyl.

Because the details of the stencil were delicate and getting the right position was important, I used masking tape to help me transfer the stencil onto the mask.

Adriana informed me that the conductive ink was not as conductive as desired and that it the conductivity should be reinforced by making some traces using conductive thread. Based on this advice, I hand sewed the traces using a running stitch.

After sewing, I used Bare conductive ink to paint over all the traces in the stencil and waited for 30-40 minutes to dry. Using a multimeter, I tested the connections and found that it was conductive where the thread was placed, but there was very little conductivity where there was no thread and only conductive ink.

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