Week 14 - Wildcard - Laser Induced Graphene (Page is a WIP!!!)

LIG EMG Face mask

Preface

AlterEgo is a really interesting project from my group at the Media Lab where electrodes on the face pick up EMG signals to the jaw to detect silent speech, talk to your computer without making a sound.

I thought it would be cool to use the programmatic circuit shaping capabilities of LIG to make an EMG face mask that was conformable and which had electrodes positioned to align exact with the muscles in the face that are used for speech.

I attempted to do a small portion of that in this wildcard week by LIGging a design, transferring to PDMS, and hooking it up to EMG circuit. Let's go!

Design

I designed the EMG breakout in Kicad. I made a custom circular pad for the EMG electrodes, set the track sizes to really big, and used the largest circular testpoint footprint (4.0mm) for the place where wires would be soldered/epoxied to.

First LIG

LIG is done by hitting polyimide with a laser. We used the laser cutter with Wedyan's special settings (1500 DPI, 1500 PPI, 8% power, 10% speed) to make that LIG LIG.

Next LIG

Then iterated on the design and settings, and redid a better one.

PDMS

To be conformable to the face, transparent, bio-compatbile, and stop the graphene from juster exiting on to the face, we transferred the LIG to PDMS.

First, make the PDMS by combining 2 PDMS agents and stir. Then put in vacuum to de-bubble. Then pour over the LIG. Then bake. Then flip and pull off the polyimide. Then it works!

Solder/Epoxy on Wires

You can't solder on wires, so we used silver epoxy to attach wires to the PDMS LIG. Baked for 10 mins at 75 degrees and it set.

MVP

First, I attached it to my arm to test if the EMG electrodes would work at all...

Final Product Test

Then cut out my mouth hole, hooked up to previous weeks EMG circuit, and gave it a test!