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Hack Chat Transcript, Part 2

A event log for Electromyography Hack Chat

Putting your muscles to work

Dan MaloneyDan Maloney 01/19/2022 at 21:090 Comments

Daren Schwenke12:41 PM
with ultrasound you probably wouldn't be measuring the nerve activity you'd be measuring the actual contraction of the muscle, but it might fill in the gaps..

hut12:42 PM
Didn't know you could use ultrasound for that, that's fascinating

RichardCollins12:42 PM
@anfractuosity Focused ultrasound was first used for surgery and cancers, I think. Getting to the level of sensitivity and care to sense and stimulate individual nerves took time and a lot of data. Most of the raw data went into human neural nets, so none of it got shared. If your group shares the raw data, there are groups world wide who can work on algorithms and clearly defined tasks and tests.

Dan Maloney12:42 PM
It's literally "The machine that goes 'PING!'"

anfractuosity12:44 PM
@RichardCollins intriguing, not sure i knew it was used for cancers. I recall touching an ultrasonic fogger thing, and it seemed to hurt a bit

hut12:44 PM
what kind of pain? heat? :)

Thomas Shaddack12:44 PM
with array of transducers you can steer the beam/focal point. lots of videos on youtube.

anfractuosity12:45 PM
yeah hard to explain heh, i guess it felt like heat

anfractuosity12:46 PM
that's interesting you're using gnuradio companion for some stuff :)

RichardCollins12:47 PM
The concept of using the existing muscles is powerful. Exoskeletons and robotic assistance is costly and clumsy. Take the "intention" signals and send them to a body controller that knows the 3D structure and properties, then determines the muscles needed and their response signals - is possible. Big data, external computer needed for prototypes, but wireless sensors and stimulation. Look at TENS stimulators, they are high voltages cheap circuits, but timing and strength can stimulate the right nerver. About 650 muscles in the body.

Thomas Shaddack12:49 PM
that's good for assistive tech/medical tech. but the force doesn't scale for exoskeleton use. different domain, though, but could also work for physical telepresence.

hut12:49 PM
@anfractuosity Yes, I found that this is the best data plotter for my purposes, although it feels like it hasn't exactly been designed for my use case :D

RichardCollins12:50 PM
The software defined radio groups are expanding and improving every day. They are into 10s of gigasamples per second at 12 bits. If you have the money you can get most anything you want. But the 10 Msps (megasamples per second) 10 bit low cost devices give you FFTs to work with in a community where some of the hard parts are done for you. Then focus on algorithms and applications.

Thomas Shaddack12:51 PM
biosignals should work with way lower samplerates.

hut12:53 PM
the highest useful sampling rate for surface EMG is around 4kHz, though 500Hz gives you most of the signal already

RichardCollins12:53 PM
You should be able to use an SDR with a tiny bit of electrical fiddling to get high sampling rate FFTs. The radio signals are microvolts. The USB oscilloscope groups are also going faster - using the same technologies. They just don't have FFT and neural net software plugged in. They can handle millivolts signals with differential amplfiers more and more built into the oscilloscope programmable amplifier front ends.

hut12:53 PM
does anybody know good dry electrodes that one could use for EMG? I'm still using very suboptimal ones

hut12:54 PM
using an SDR for processing biosignals sure sounds interesting, haven't thought of that

Preston12:54 PM
I'd imagine the dry EEG electrodes (either gold or Ag/AgCl) would work, although I've never tried

hut12:55 PM
will try them out

hut12:56 PM
thank you @Preston

hut12:57 PM
if you have any more questions after this session, you can come to PsyLink's Matrix chatroom any time: https://matrix.to/#/#psylink:matrix.org

the_3d612:57 PM
@hut we have some limited success with conductive fabric - but can't say I'm satisfied with it, looking for better options

perlinwarp12:58 PM
@hut You know I'm using brass or silver-plated corkboard pins or copper shimmies from laptop CPUs since theyre both cheap, but I'm yet to have a good comparison between them (https://github.com/PerlinWarp/pyomyo/wiki/The-basics-of-EMG-design ).

Anyone know if these are horrible ideas? ahah

anfractuosity12:58 PM
doesnt copper / silver tarnish though?

hut12:59 PM

hut12:59 PM
older prototypes used snap buttons that are typically found in jackets or other clothing

RichardCollins1:00 PM
Electron paramagnetic resonance spectroscopic microscopy, and NMR imaging spectroscopic microscopy and other groups are trying to measure (non invasive) nerve activity. The microscopic is mostly cubic millimeter voxels, but people go larger. Imaging ultrasound can modulate electrical signals so groups are combining EEG MEG (magneto) and other non contact electromagnetic measurements with ultrasound. All for tracking nerve activity.

Dan Maloney1:01 PM
And just like that, our time is up! Really good discussion, great way to kick off 2022! I want to thank hut for his time today, and all of you for the great questions and insights. Feel free to keep the discussion going here, you're welcome to stay as long as you like. Thanks all!

hut1:02 PM
Thank you Dan for inviting me!

Dan Maloney1:02 PM
You're welcome! And everyone make sure you come back for next week's chat:

Nicolas Tremblay1:02 PM
Thanks @hut

Dan Maloney1:02 PM

https://hackaday.io/event/183427-compliant-mechanisms-hack-chat

anfractuosity1:03 PM
that was really cool! look forward to reading more about your project :)

Nicolas Tremblay1:03 PM
the link isn't valid

the_3d61:03 PM
Thanks everyone :)

RichardCollins1:03 PM
The stakes are high. Many people become paralyzed from accidents and diseases, but also drugs and stroke. So tens of millions need devices to measure "intention" by nerve activity or small muscle movements - and translate that to muscles stimulations or to machine controls. The intentional use by anyone means driving vehicles and operating complex equipment.

Nicolas Tremblay1:04 PM
sorry, now it's good

Dan Maloney1:04 PM
@Nicolas Tremblay - Sorry about that, it was still private. I changed it to public

Dan Maloney1:04 PM

https://hackaday.io/event/183427-compliant-mechanisms-hack-chat

Dusan Petrovic1:04 PM
Thanks @hut !

hut1:04 PM
@anfractuosity For more news, you can subscribe to the RSS feed of the development blog [https://psylink.me/index.xml] or follow PsyLink on Mastodon: https://fosstodon.org/@psylink

anfractuosity1:04 PM
oh cheers, i like rss too

Daren Schwenke1:05 PM
thank you @hut and everyone else for a 'stimulating' conversation.

hut1:06 PM
my pleasure, thank you all too!

perlinwarp1:06 PM
Thanks everyone, especially @hut and @Dan Maloney !

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