
Man compares his prosthetic hand to a 3D-printed one - brian871
http://www.3duniverse.org/2014/04/19/jose-delgado-jr-compares-his-new-3d-printed-hand-to-his-more-expensive-myoelectric-prosthesis/
======
graeham
Cool project, but the $42,000 prosthetic probably has only $50 in materials as
well, the expensive part is the engineering, fitting, and assembly. Not really
a fair comparison.

Models like this are quite exciting - assistive devices and prosthetics are
incredibly expensive due to low volume and customisation requirements. This is
preventing innovation and production of new devices and technologies.

They are also (rightly) highly regulated. A next step is trying to figure out
how to maintain quality and safety in these kinds of DIY projects.

~~~
nimblegorilla
> They are also (rightly) highly regulated. A next step is trying to figure
> out how to maintain quality and safety in these kinds of DIY projects.

I can see why medical devices like pacemakers or implanted replacement joints
need more regulation, but I don't understand why a prosthetic needs more
regulation than other consumer products like gloves or eyeglasses.

~~~
icegreentea
I broad terms I agree that there's probably too much regulation on medical
devices in general. There are a variety of areas where there can be
considerable stream lining or reduction to the net benefit of all parties
involved.

That said, the myoelectric device at a minimum falls under some level of
regulation since it is a biopotential device. The moment you start measuring
potentials on the human body, you add the risk of injecting current across the
human body - obviously bad. If you wanted to ensure that the myoelectric
device was safe, you would at a minimum ensure that a) sufficient isolation
between the sensory and actuator circuits b) a safe sensory circuit. Now,
while doing that is probably relatively trivial to actually design, you do
need to verify it.

So, once again, I agree that there's probably too much regulation piled on,
but there is a good reason to regulate/verify in some form or way at least the
myoelectric device.

More generally, notice that the examples that you and sister component pointed
out are relatively simple, especially compared to a prosthetic hand.
Complexity in itself can cause the need for regulation.

Oh, and on the side, you may find this document with regards to impact
resistant and safety glasses
([http://www.fda.gov/medicaldevices/deviceregulationandguidanc...](http://www.fda.gov/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm070579.htm#3))
a fun read =P.

------
dang
The original url [1] was blogspam—that is, it was a knock-off of some other,
more original source. In such cases HN strongly prefers the original source.

All: when you know of a better, more substantive version of a story, please
alert us to it in the comments. There's too much material for moderators to
check, so community effort makes a big difference. Let's optimize for quality.

1\. [http://3dprint.com/2438/50-prosthetic-3d-printed-
hand/](http://3dprint.com/2438/50-prosthetic-3d-printed-hand/)

~~~
gwillen
Thanks for commenting with an explanation of your moderation (not just this
time; I've seen you do it repeatedly.) It really makes a huge difference to
how moderation on HN is perceived. (If you look at my comment history, you'll
see that I have a history of somewhat passive-aggressive comments about the
opacity of HN moderation. I really do appreciate the change tremendously.)

~~~
dang
Thanks for saying so! That's exactly what we are hoping to achieve.

~~~
tripzilch
Seconded! (what gwillen said)

------
habosa
For anyone on HN who hasn't had the opportunity to use a 3D printer I really
recommend that you find a way to use one for a few hours. The experience of
willing something into physical existence with a few clicks in Solidworks is
amazing. If you remember the feeling of the first time you made the computer
say "Hello World" or the first time you set up your own website, you'll get a
similar rush from 3D printing. I've been lucky enough to have access to one
for my final project at school and it's made me so much more ambitious with
how I can design and has made my iteration speed at least 10x as fast.

~~~
FigBug
I'm a software developer, but I got a copy of solid works from work. I tried
to design a Garmin mount dog collar and failed miserably. I then asked a
mechanical engineer to do it for me and he whipped it up in a few minutes. I
was humbled by how hard it is to design physical products.

If anybody wants to track their dog:
[http://www.shapeways.com/model/1805713/dog-collar-garmin-
mou...](http://www.shapeways.com/model/1805713/dog-collar-garmin-
mount.html?li=shop-results&materialId=6)

~~~
habosa
Yeah it's an entirely different skill set. I have 3D printed a lot of parts
for my recent project but it's all rectangles and circles, I couldn't get
anything much more complicated to come out right.

One of the things a mechanical engineer friend of mine suggested is finding a
cool SolidWorks file online and learning from it. Basically drag the bar of
the feature tree all the way back to the top and you can "play back" the
person's design step by step.

------
DanBC
3D printing of prosthetics is really exciting. Here's a video showing what
poor people were doing before.

[http://youtube.com/watch?v=Yvev6shNvSg](http://youtube.com/watch?v=Yvev6shNvSg)

[http://www.ncbi.nlm.nih.gov/m/pubmed/19367513/](http://www.ncbi.nlm.nih.gov/m/pubmed/19367513/)

You take an old soda bottle, cut the bottom off, and use heat to shape it to
the stump. You can fix lightweight tools (forks, combs, button hooks, pens) to
the screw top lid.

------
ludicast
This is disruptive. This is the first time in a long time I can say that
without imitating a vc/wantrepreneur etc., but be serious.

Obviously there is a lot of data missing here, but the fact that it is even
approximated is amazing. Imagine the possibilities for people w/o insurance,
veterans, inhabitants of poor countries.

Imagine if one day amputees etc. have a standardized interface to their
nervous system that controls their hands. Then all 3d-printed hands need to do
is adhere to that spec and people can put their health/abilities in their own
"hands".

Very cool and the more geeky/creative amputees could actually build tools into
themselves to use for fun sometimes. Granted I'm speaking for people when I
have no idea of their struggles. But as Kramer said once, I'd like to have
"shoehorn hands".

------
userbinator
_open source 3D printed hands_

Something about that phrase just sounds really, really awesome.

------
zackmorris
I would like to see the middleware between sensors and motors be open source.
To me, it seems like the complexity in prosthetics is not the mechanics, but
interpreting the signals properly to control the device.

It seems like a relatively rudimentary neural net with a lot more electrical
sensors than today (maybe 16 to 256, something on that order) combined with
some of the new sensors like light transmission or even maybe ultrasound to
"see" the muscles under the skin, could be mapped to a graph with roughly the
same degrees of freedom as the human hand.

Then maybe something like KNN could sift the data and map it to the motors.
I’m not very familiar with data mining yet, but surely a lot could be done
with a 700 MHz Raspberry Pie and a few GB of SSD storage. I’m thinking that
giving the algorithm some notion of time by recording 1/60 of a second slices
or something in that range might really improve accuracy. Just throw data and
processing at it rather than trying to fully understand how nerves work.

Doing the reverse, to stimulate nerves based on how much power each motor is
using, should be simpler. It could be sloppier because the human mind would
learn to interpret the signals better than a computer.

The software should be available for free online and work with commodity
hardware, and then the prosthetic designer could customize the limb for each
user. Plus it could have the ability to upload random samples to help train
the next generation AI.

As long as I am dreaming, we also need a moonshot to standardize nerve
implants. It would go inside the limb somewhere and then use something like
802.11 powered by inductance coils above and beneath the skin, with a faraday
cage built into the arm to prevent interference. Actually now that I say that,
I wonder if the noise produced by the body’s movements would be statistically
significant enough for another input into a neural net.

Anyway, chemical markers on the terminals could urge the nerves to grow into
the terminals. Or use a bit of foreign nerve tissue that’s been grown on a
scaffolding in the device in the lab, and then implant it and put the patient
on immune suppression drugs until the nerves grow together, and then take them
off gradually until the body dissolves the foreign nerves and has a direct
connection to the sensor. Another idea would be to press a comb-shaped device
with hundreds of microscopic channels through the nerve bundle and read the
voltage through each channel. It should be manufactured for longevity and to
read the most amount of data possible, and just let the programmers work out
how to sift through it.

Once we had good data, training a neural net to do the mapping to actuators
seems like a basic problem. Like maybe sample a few hours’ worth of movements
and put the whole thing online like the Netflix contest until someone has
programmed a near-perfect AI. Or a series of contests, each aiming to raise
accuracy by 10% or something.

~~~
Balgair
Ok, wow, this is my area of expertise actually (well, in process at least).

Lets go through your post and comb it out. I really love the enthusiasm and
ideas. My biggest caution going forward though: The body really dislikes
foreign objects, like really.

>"...it seems like the complexity in prosthetic is not the mechanics, but
interpreting the signals properly to control the device."

You couldn't be more correct! Dr. Richard Weir at CU Denver[0] has some great
work in 3-D printed hands. The lack of controls into the hands is a major
concern. The issue is you only have so many muscles in the arm to control all
the complex motions of a hand. His group is working on the eigen-states of
hand movement, trying to decompose them into the number of muscles in your
arm.

Why the arm? Well, it makes sense to focus there, as that is where patients'
minds are focused. The method is myocardial sensors that sense the nerve
firings in the peripheral nervous system and then can send out that data. You
basically implant them in a muscle fiber and they last a long time.

>... a lot more electrical sensors than today (maybe 16 to 256, something on
that order)...

This would be awesome. But, focusing on a prosthetic hand, we don't have that
many muscles in the arm to control that many[1]. The hand is much more
complicated than the arm. Decomposing gestures, as Dr. Weir is doing now is a
good step in that direction.

>...Just throw data and processing at it rather than trying to fully
understand how nerves work.

How true this is! Much is being done in the Big Data era of neuroscience that
we live in. Many groups are trying this tactic[2]. The thought is to just
describe what the system of a brain does, not how it works. Think Gaussians,
not Markov chains.

>...Doing the reverse, to stimulate nerves based on how much power each motor
is using, should be simpler.

Feedback is very important to prostheses and helps improve care and quality of
life. However, directly stimulating nerves is difficult. Your fingertips have
much better 'resolution' than your elbow does[3]. Also, your skin also becomes
accustomed to the input and you will ignore that stimulus pretty quickly. Like
how you notice the smell of the food when you walk in the door, but don't
within 10 minutes of standing next to the stove.

>...It could be sloppier because the human mind would learn to interpret the
signals better than a computer.

The body does acclimate to the stimuli, but as I said before, it also starts
to ignore as well. Also, people are all different. Genes can account for a lot
of the differences, as well as environment, but also even culture and
gender[4]

>...As long as I am dreaming, we also need a moonshot to standardize nerve
implants.

I'm not sure what you mean here. Each person's situation is very different and
personal. Standardizing is difficult with medicine.. Skin color, size, weight,
culture, gender, job, etc all greatly vary. For example, a scuba instructor's
situation is a lot different than a 1st grade teacher's. The scuba guy has to
deal with greatly varying pressure and water. The teacher has to have the new
hand be fit for children. The nerve implants will have to follow their
situations.

>...a faraday cage built into the arm to prevent interference.

Your blood is mainly salt water, which is very conductive, so there is not
real need to cage things. In fact, you want to encase everything in silicone
to prevent leaks and make it all non-bioreactive.

>...the noise produced by the body’s movements would be statistically
significant enough for another input into a neural net.

The noise in a muscle is hard to figure out. Again, it depends on the person,
the muscles, the salt content in the blood, etc. In a nerve, the picture is
much the same. I will quote without citation that the firing rates of nerves
increase with temperature to the 4th power (I'd love a citation, if anyone can
find one, my brain is just borking now)

>...Anyway, chemical markers on the terminals could urge the nerves to grow
into the terminals.

This is non-trivial and may not be possible. Those markers often are only
present in a real soup, and the behavior of nerve growth is not well
understood (at least by me, haha). I'll admit it's possible, but a lot of
engineering is needed to do it.

>...put the patient on immune suppression drugs until the nerves grow
together,

Wow, that is not a good idea. Going on immunosuppressants is not taken
lightly, and you'd have a heck of a time convincing people to take that big of
a risk just for a hand or something. Also, they won't be necessary in the
peripheral nervous system, just the central nervous system.

>...Another idea would be to press a comb-shaped device with hundreds of
microscopic channels through the nerve bundle and read the voltage through
each channel.

Dr. Theodore Berger at USC is working on a device like this already![5]

>...It should be manufactured for longevity and to read the most amount of
data possible, and just let the programmers work out how to sift through it.

If you'd like to join up, many neuroscience departments really favor physics,
CS, and EE majors for grad study these days, at least it seems to me like they
are.

The peripheral nervous system is a real good area for these neural ideas. But
the central nervous system (CNS) is not. The reason is glial scarring[6]. You
body really really does not like things in the CNS. This is why paralysis
happens mainly. The scar prevents the nerves in your spine from regrowing and
making the legs and whatnot work again (sort-of). This takes place in your
brain to a huge degree. I used to work with place cells[7](very cool cells)
and everyday we would have to 'burn off' the scarring by passing current
through the electrode bundle. It turns out, you are your own worst enemy here.
Ideas like opto-genetics[8] can bypass the scarring issues, but they also have
a host of others.

Again, great ides and enthusiasm! I love it! If you see a future with
neuroscience, the field is wide open these days and there seems to be a bit of
money floating around. Apply to a progam or 12 and you'll have a great time.

[0][http://www.ucdenver.edu/about/newsroom/newsreleases/Pages/Bi...](http://www.ucdenver.edu/about/newsroom/newsreleases/Pages/Bioengineer-
developing-prosthetic-hand-and-fingers-that-perform-full-range-movement.aspx)

[1][http://www.innerbody.com/anatomy/muscular/arm-
hand](http://www.innerbody.com/anatomy/muscular/arm-hand)

[2]It's easter, I'm not counting how many! You do it.

[3][http://visalakshiramani.files.wordpress.com/2010/07/homuncul...](http://visalakshiramani.files.wordpress.com/2010/07/homunculus.png)

[4][http://ccr.sagepub.com/content/34/2/135.abstract](http://ccr.sagepub.com/content/34/2/135.abstract)

[5][http://www.usc.edu/programs/neuroscience/faculty/profile.php...](http://www.usc.edu/programs/neuroscience/faculty/profile.php?fid=23)

[6][https://en.wikipedia.org/wiki/Glial_scar](https://en.wikipedia.org/wiki/Glial_scar)

[7][https://en.wikipedia.org/wiki/Place_cell](https://en.wikipedia.org/wiki/Place_cell)

[8][https://en.wikipedia.org/wiki/Glial_scar](https://en.wikipedia.org/wiki/Glial_scar)

~~~
joeyo
At the risk of some inside baseball: there is growing evidence that "glial
scar" encapsulation (and microglial activation generally) is not main the
cause of neural interface failure. Rather, oxidative stress [1] or other
neurotoxic factors [2, 3] released by microvascular damage / blood-brain-
barrier disruption seem to be the most correlated with interface failure.

What then to make of the widely observed phenomenon that passing small DC
currents through electrodes can temporarily rejuvenate them? It could be that
this effect is a result of an electrochemical change to the electrode surface
itself, rather than to the surrounding tissue.

1\.
[http://www.ncbi.nlm.nih.gov/pubmed/24550823](http://www.ncbi.nlm.nih.gov/pubmed/24550823)
2\.
[http://www.ncbi.nlm.nih.gov/pubmed/23562053](http://www.ncbi.nlm.nih.gov/pubmed/23562053)
3\.
[http://www.ncbi.nlm.nih.gov/pubmed/23891081](http://www.ncbi.nlm.nih.gov/pubmed/23891081)

------
twic
People might also be interested in Project Andiamo, a startup in London that
is going to use laser scanning and 3D printing to make custom-fitted orthotics
for disabled children:

[http://projectandiamo.com/](http://projectandiamo.com/)

It was founded by a couple who had a disabled child who needed a back brace,
and were horrified by the current process for getting one. The measuring
process is upsetting for the child (it involves taking a slow-setting wet
plaster cast), it takes weeks to make the brace, it's expensive, and when it
finally arrives, it fits badly. They think they can turn round a perfectly-
fitting brace from laser scan to 3D print in a couple of hours.

It's a totally brilliant project. It's very rare that an idea is so obviously
right.

------
tiziano88
Note that the expensive one has myoelectric sensors and electromechanical
actuators, while the 3d printed one is purely mechanic, which means it might
not be suitable for all the people without a hand (my guess is that it needs
at least part of the muscles of the wrist to be present and working correctly,
as they are effectively moving all the mechanical parts in the hand).

------
NoPiece
The 3d printing angle is cool, but I'm also curious in how much the cosmetic
focus of the expensive hand held back the functionality. It would be
interesting if people were moving past the need to have a real looking
prosthetics, and towards having more functional, but clearly robotic
prosthetics.

------
holri
Why didn't he compare it to the Greifer laying on the table? The myoeletric
device he compared the 3 printed one to was the cosmetic hand. The workhorse
is the Greifer, which is a much better device for working and handling than
the cosmetic hand.

------
brador
Why stop at just replacing human parts? Augmentation is the awesome
possibility here.

------
marincounty
I really think one day the 3D printer will be commonplace. I know the
Physibles are pretty much useless now(the ones on that bad boy site), but once
they start programming everyday stuff--like enclosures for spare hard drives,
or a knob for my '54 chevy radio; more people will might take a second look at
the technology. Yes--I used Physibles because I think it's a good catch all
word for the different types of files.(I am in now way comparing radio knobs
to prosthetic hands.) I am so glad the medical community is embracing these
printers. Happy Easter!

