When Darth Vader slices through Luke’s wrist, severing his hand ya gotta imagine that hurts!
But the physical pain he feels is nothing compared to the emotional pain he experiences
when he learns that Darth Vader is his father.
In the Star Wars universe, daddy issues take at least a couple of movies to resolve - but
losing a hand is no big deal.
Just a few cuts later, we see a droid putting the finishing touches on Luke’s brand new
prosthesis - after a couple of shocks, he snaps the panel closed and it’s like he
never lost his hand.
Like lightsabers and hyperdrive, this advanced medical technology is lightyears away for
us here on Earth - or is it?
Neuroprosthetics are biomedical devices that use neuroscience and engineering to complete
or replace damaged or missing systems - these can include sensory systems, like sound and
touch, as well as motor systems, like walking or throwing a ball.
A common example would be a cochlear implant - these small devices can be used to restore
hearing in people with damaged cochlea, an integral part of the auditory system.
They’re implanted into the skull, and translate sound into electrical signals, which it then
passes to the auditory nerve, bypassing the damaged part of the ear and sending the auditory
information straight into the brain.
But when you think about Star Wars, you think about prosthetic hands - after all, Star Wars
characters lose arms at an average rate of two per movie.
Simple modern prosthetic hands are body powered - users can operate them without any extra
motors or attachments.
Common models include voluntary open and voluntary close designs, when a wearer uses their own
muscles to pull internal controls on a specially-engineered prosthetic hand so it will either open or
close.
These are handy for increasing the utility of a prosthetic hand - being able to pick
up a pencil, or hold an orange, are underappreciated but important abilities.
Voluntary close designs can even provide some basic tension feedback, making it easy for
the user to sense how much pressure they’re exerting with their prosthesis.
These prosthetics are handy and easy to produce - they can even be easily and inexpensively
made with a 3D printer!
But their range is limited, and without much sensory feedback, it’s hard for the user
to perform fine manipulations.
Myoelectric devices are not quite so lightweight or durable as body-powered devices, but they
do have some advantages.
These prosthetics use electrodes to detect electromyographic signals from remaining skeletal
muscles in the arm, and use that information to move and operate the prosthetic hand.
Electrodes placed on the skin can detect the signals of a couple different groups of muscles,
allowing control of movement in multiple dimensions, like opening and closing the fingers and rotating
the wrist back and forth.
This means that these hands tend to have a greater range of motion and finer motor control.
Researchers are working to identify ways to design these devices, along with better AI
and programming, so they can detect even more movements to provide even greater control.
But in the movies, Luke’s hand isn’t just strapped on; it appears to be integrated with
the rest of his body and nervous system, essentially appearing and functioning like a real hand.Maybe
that’s because in 1983, it was easier to just put a glove over his real hand than build
a functional futuristic prosthetic - or maybe it’s because in the Star Wars universe,
they’ve mastered brain-computer interfaces.
A brain-computer interface is basically exactly what it sounds like: a direct connection between
the brain and a mechanical prosthetic, using the brain’s own electrical signals to provide
information to control the movement of the device, and ideally sending electrical signals
back to the brain to provide sensory feedback.
This can be done using microelectrode arrays - these are small plates with multiple tiny
electrodes embedded on them that can detect the electrical signals of neurons, and/or
produce electrical signals that activate neurons and make them fire.
In 2002, a neuroscientist named Kevin Warwick had an electrode implanted into the nerve
fibers in his forearm.
The electrode, working in tandem with a computer built into a separate, prosthetic hand, allowed
Kevin to manipulate and control the device.
Thanks to the sensitivity of the device, and the feedback it provided, he could grip objects
without needing to see them - he was even able to operate the hand via an internet connection
from a different continent!
After training, he could use the hand to carefully control the movement of an electric wheelchair,
demonstrating how the advance could help users achieve more control and independence.
This gets us one step closer to Luke Skywalker’s hand.
In fact, research presented at the 2017 Society for Neuroscience conference shows just how
far we’ve come.
A group of scientists at the University of Utah developed a device called the Utah Slanted
Electrode Array, or USEA for short.
After mapping out the nerves of the hand and arm and building algorithms to translate robotic
sensors into touch signals, they’ve designed a device that might just be the future of
prosthetics.
This electrode, implanted in the arm, detects signals directly from the remaining muscles
to move a robotic hand - and can stimulate the remaining nerves to provide sensory feedback
from the hand, creating a feedback loop, so users can actually /feel/ the hand.
Our brains incorporate sensory information like sight, sound, and touch to help us move
our bodies in space.
So being able to “feel” a prosthetic hand allows users to operate their new limb more
naturally, and maybe even allow them to feel more ownership of the arm.
And by working with advanced robotic hands, it seems like the array is doing the trick.
To see how well it works, they’ve been using a high-tech robotic arm designed by DEKA - dubbed
the “Luke” arm because of its dexterity and complexity, like Luke Skywalker’s hand
in the movies.
Initial testing with just the implanted electrode allowed a user to “feel” the textured
surface of a virtual wooden door - and once he was hooked up to the robotic prosthesis,
he was able to pick up an egg without crushing it, and even hold his wife’s hand.
Jacob George, a bioengineering graduate student working on the project, explained how this
technology is not just helpful for making a prosthetic hand look more natural - it actually
increases the user’s sense of ownership over the hand.
According to researchers, the device reduced phantom limb pain, and a test subject even
described it as “his” hand.
Ideally, says Jacob, the technology will progress to the point that a user won’t even have
to /think/ about using the device - it will simply operate exactly like a real hand.
But everything isn’t all Jedi-friendly yet.
Current drawbacks on these devices are their limited lifespan - we still haven’t figured
out how to design electrodes that will last a lifetime without clogging up - and the fact
that we’re still mapping out all of the motor and sensory signals required for using
our hands.
And, these devices are /expensive/, and new - the Luke hand and the USEA are still in
experimental prototype stages, so users only get to use them in a laboratory setting, not
when they’re going about their everyday lives.
So how close are we to having Luke-style hands?
Well, we’re not quite there yet - but we’re maybe closer than you would think!
Thanks for watching this episode of Neuro Transmissions.
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Until our next transmission, I’m Alie Astrocyte. May the Force be with you.