PolySense: Reverse Engineering Flex Sensors, and Destroying Your Kitchen With Chemistry for Electrical Functionalization of Everyday Objects
8:05PM Aug 6, 2020
To add electrical functionality to various materials.
You can create clothes which measure your body movement, provide heat in the cold, or even track your motion for VR, or lightened sound control. Our next talk is about fabric augmentation using tools you can find in any kitchen, we prevent. We present Cedric on a with Polly sense,
reverse engineering flex sensors and destroying your kitchen with chemistry for electrical functionalisation of everyday
Hi everyone, my name is Cedric, and we are going to present for instance, an accessible process that makes families smarter. Okay, so. This presentation will be chronological from the original problem to solutions,
followed by a few unexpected discoveries and opportunities for the future.
Let's start with the initial motivation.
So, this project was done, a hackerspace could achieve focus on epic size, such as this matrix. Pressure Sensor. So he started here I think so, uses two kinds of materials. This, this case, first the conductive fabric. So on the right. We can see horizontal stripes used to sequence and power the center or rasterization. On the left, we can see vertical stripes that are connected to the analog input of the afternoon. With a bit of
bass used to pre process the signal. And as we know, reports the signal to the computer.
And in the middle. You can see a darker fabric.
This is the typical resistive material. It changes its resistance when you press it. This material is expensive. It's about 200 grams per square meter. And it became harder to get over time. So, with this kids resistivity anyway. One of our growth on this project. And I'm gonna reason maybe some of you met her last year she was giving a couple of sessions and excite. And she did this really cool visualization of what's happening inside. So we illustrated here as a layer of conductive particles are these brackets. But I think it's better to see it as fibers that were cut, and it's like a perpendicular position of the fabric. So windows pressed together. The overall conductance increases, because each of them is fully conductive but stay connected. So the fact that the conductance increases, it makes complete momentary behavior in the resistance. So, the resistance decreases when we can measure that with the IB. So we try to make our own coating with silver, copper, carbon particles, and we really never got anything that were either would oxidize, it would not conduct at all.
It's actually a difficult challenge, but
we realized that we didn't really understand the material.
And fortunately I made train with a collaborator on that predictive analytic system from this book. And I spent a week in her material science lab. And after a few analyses, including Raman spectroscopy. We understood better, what could be in this reference better. So the Raman spectroscopy, to look looks a lot like a laser, but it's actually much smarter than that. What's happening inside is that there is, so if you click on a microscope. And it has a laser that shoots light in whatever you're observing and it looks at what is coming back. The lightest burst at a certain frequency. It's actually a scan wave frequency and. And you can see what comes back, a bit like. Let's try with it. If you think about it on the acoustic domain. When you knock on that. Okay, maybe do something. Okay. You can hear a specific acoustic signature. And when you look on something is unlike my phone. You can hear a different kind of sound. And this can be represented as a spectrogram. Well, This tool that I'm showing on the screen is doing the same but instead of sending an acoustic inverse, it sends a, an optical inverse. And we can see at the bottom right, some spectrograms that are representing the materials that we are observing. So, with the software you can point at the specific part of the material that you want to observe and it will tell you something like this looks like carbon graphite PSS or many other kinds of methods. And in our case, It's another one that I'm going to say thanks to the expertise of those friends, we have various ways to replicate this amazing TED Talk. That has this interesting behavior. And we really work on optimizing. A simple process, but you can repeat it in your kitchen, so you don't need this mad tool that you can see on the screen. We found this simple approach that only use two chemicals. One is called the hero. It's a monomer, and I'll explain a bit later What are those things what what are their functions and what are their behavior, and the other is iron chloride. It's a fairly common chemical that is used in to make PCBs, so when you,
when you make a 3d printed circuit board.
Like the classic Arduino or whenever you start from the State of Qatar and you cheat with this thing. Most of the time,
or claw back right. It has different names. Anyway, it's fairly common in state.
So, we use the magnetic stirrer, and you can see at the bottom there. But you could use whatever you want the washing machine to Blender I think you do better.
Another Blender that does make juice though because
So yeah, you can do whatever you want. And we obtain pressure sensor in about one hour with all of the setup. So you can set the break. The first test that we, so we drive the site, and we just measure the Z pressure. So the pressure between the bottom and the top.
But we can measure the pressure, the resistance in different ways.
this took a bit divided applications. Here's one of them. One of the applications that we did, we demonstrate one of them with, again, but this one is musically and of the shapes that we functionalized. In it you see how you can function a nice materials. If you say things. But you take these thing and you cannot die. It's a molecular level day. And in this case we can measure when fingers are fixed pressure at the intersection. And we applied to a virtual reality game. So you can imagine something of motion capture
And as for all of our projects. This one is open source, and you see the GitHub repository again, in most of the slides here. So far, another conference called augmented humans, we presented this
project, which is using on the shelves. Can you
have it here
normally comes in long bend,
and you stick it on your skin when you have
when you damage your joints physically. So for example, you should dislocate your shoulder, and the shoulder to maintain. It has this interesting property that it's stretchable in one direction,
but not in the other.
normally, it comes with a beautiful white paper on the back, but this one we we died. Are we functioning nicely with our polymerization. And at the end, the paper is kind of dark, but it's sealing that. So, as you imagine if you stick it on the skin you have some kind of groove on one side, and it's just some classic fixate on the other side. So in this case we this. What we're seeing on the screen, we're not using the stretchability, but we'll show another one later. What is interesting here is that we use the finger analog input. I don't know if you see your screen but there is a ring, made of copper connected to a cable that goes to an Arduino it goes to the analog input, and then under two ends of the kinesiotape stick on the hand or the left hand of our test subject. We have this thing that is basically behaving a bit like a linear slider it's a it's a potentiometer. And so the hand comes in by getting close to the red, you will get something that is close to the voltage input at the red crocodile. So these use five volts and whoops. And on the other side it's grown. So when you are close to the red you have five and when you're close to the black you have something like zero, something we can type into. And we can see the visualization that shows how to estimate the position, according to this webpage. Super simple processing sketch. Again it's available. Yeah, basically, how to make a human potentiometer,
which are some other application.
So those small embedded applications that we just saw, one might wonder how scalable is this process. So this installation uses several meters of this textile. The light is not amazing but actually you can see. So, this is a polyester textile that's somehow replicating since we functionalized it after doing a kind of shibori. Yeah. And then after functionalizing from simulasi. It was not so red anymore. Originally it was red. And then he became became very dark where we functionality. And then, we created it. I don't know if it's visible but it has this interesting kind of squishy folded structure that will create an amazing passive active feedback. These are the application is basically functionalizing feathers in. So in the previous example we were doing
artistic visualizations, not with shaders but. And
in this case it's on sophistication so when you touch
it there. It's behaving like a capacitive sensor. So basically the sensors in our screens on our phones, the things that you touch it, and you can use it with an Arduino to trigger sounds. That's basically what happened. This example shows that you can functionalize, other things that excite. We. Yeah, we tried it, and most of the things that are poles are fibers, they should weigh, except when they are very synthetic like a
piece of very thick
synthetic textile usually doesn't work with. Anyway, you might recognize Hannah Wilson. So just after it became last year we went to this conference in Germany consistency is the biggest hackerspace conference in the world at 18,000 people in the winter and in the summer it's every four years it's smaller, and it's, I think was 5000 people. It's a big thing it's really worth it if you have the opportunity to actually if you have to get the tickets but it's worth it. Anyway, and I was showing her slides, by folding her knees into now. So we functionalized this tent and, and with some connections. Not enough. In this case, kind of a little bit No, it's good x, x IO. It's another kind of bone above, you can send signals in and use them for shape changing your slides officer position or whatever. It was really one, and we realized, kind of, with a lot of stress. I think for the links in the basically the humidity of sweat is changing the values that should be. So you have to think about it when you make your own sense or if you make it wherever we didn't know at the time, we discovered it's a great community center. And we discovered that painfully. And on the other applications, we realize that you can also one, or you can shoot your user by putting electricity on the, on the dark side. So in this case, it's basically as anything resistive if you put electricity. Because it doesn't conduct very well. So, it kicks in when you start hitting into that you can identify very fast. The same connection can be used to measure the resistance, after you hit it, and it happens that the resistance changes with the temperature. So you can actually use it as a temperature sensor to. You don't even have to eat it but it's interesting because if you heat your user, you can avoid burning him or her. As you can see here we have some smoke. It was pretty fast if you put it off current. So if you want to make something from burning mind and making the perfect it works really well. We had a few guns on flames. You can see with this infrared visualization that was fairly hot. And we characterize the temperature versus resistance. So we can create these kind of crunchy add to loop. Lows regularly with like your thermostat at home. Those regulating the energy that you've sent to your to your heater, to keep it at regular temperature.
So, you don't want your user to
put on fire
is a zip. That was white originally zipper. So if you measure the resistance between those two sides. You have this kind of constant resistor. That is for the value something that 400 k 600 k something like that. And this is metal. So when you close it, you shorten the path of the, of the electricity. And you get enough. Enough slider, or potentiometer. So you can you can use it as a future in this new kind of music application, you can use it as a potential method that you can that can keep its position. Whereas, the normal purchases are more like for. It's a worldwide shake or. This one would be more like you change the volume or change control Tina's mom about being stable. So this is an off the shelf
zipper that just was white.
Made out of
cotton. And they all work. One trick if you do your own is that the second step of the polymerization is oxidizing the middle so you need to clean. After the process with flux and media. If you have a heat gain
to dissipate the effects.
So, we saw a few polymerization that we did go in various festivals and conferences. Now you might want to know how to make your own. We have this application that describes all the stage. But let's do it step by step together. So in our case we use the washing machine to make a lot, but as I was saying earlier, you can do small mixing things by hand. And I did a lot of this by hand she was not really a fan of the machine. Just enough a wire.
So, yeah. First, you put the water.
And you should use a bit less than twice the amount of fabric that you're going to need, knowing that the thing will move around and it's nice if, if, if you have a bit, bit more pleasant way. I think between 1.5 and two times just saw the whole thing and just the water access. That's important. Then you put the monomer. So in our case it's pure oil intriguing to buy the thing if you want. So, this is a bit toxic before it reacts with the second chemical product. It's hyper super sexy it's a bit similar to. If you're using like a strong alcohol for like cleaning stuff or you don't want to put it in your eyes don't drink it in your mouth. It's not nice. It stinks. So, in our case we use girls and girls and even
mosquito breeding sheep.
I do that, fairly often in the kitchen or in my hackerspace. It's fine. Once you have this mix, then you get the dig site you soak it for like 10 minutes. And you can maneuver memorization, which is basically bringing all of those monomer chemical particles everywhere in the favor. And then you add the oxidizing agent, which will trigger the personalization. So hints are incorrect. In our case, it comes as, you know, powder or crystals, you break them and you dissolve them.
And then you meet
again this is kind of toxic you're alone, and
it's meta is not super nice on your skin. At the end if you put it on your skin which I did many times, you feel like super dry hands. So, but it's spotty but he's not super nice. So, that we trigger the, what is called the Institute for memorization. I'll explain that a little bit. But concretely, if you want to make kids resistive sensors, so the one that measure the pressure, about half an hour works most of the time, would be 45 minutes fussing with the materials. You want to make as defenses, as the one that I was showing earlier. That was like seven meters. Two hours is really the minimum for capacitive sensors. In our case, we were making several meters, several yards of these textile availables, maybe six by 10 or something like that. And we folded in. So it's not exactly a lot of time. And we several machines of this seven, seven nights. Yeah, we done one night of premeditation, but basically the longer you put in your eyes. The bigger the conductance will be. Yeah, our chains of monomers. So the monomer is what we see on the left is just one element could cure in our case, and the printer is a long chain. Here we just so far them but it's really long, the chains of monomers that are built around each fibers, almost like if they were merged with the Tiber small on the coating. I like to call the Big Bang. You can imagine that the fiber itself becomes conductive. And this is good institutionalization because the modem is already everywhere around the fiber already soaked in the fiber somehow. And when you trigger the putting memorization if we couldn't act with all of its friends and create these conductive particles that are very long. And this is the trick. We tried so many approaches and we couldn't imagine that first there was this thing, puron that existed we didn't know the way of making it in two steps like that is the technique. So, If there's something that you have to remember in this process is that it's Institute. And it's this two step process that creates this conductive change. So this polymerization is mostly creates chains of carbons, at the end, and actually not toxic, we did some tests with the material science lab, and the technical way of doing is that you take some skin cells that are still alive and you mix them with the result of the polymerization, and you do the assay life 24 hours later, it's considered as non toxic. And this is saying that this process for another application which is basically using these functionalized materials as what they call, text aid batteries. So what they do is they use another layer of another chemical and they put it underneath the armpit, and they use the suite to generate a chemical reaction, which creates energy, there's an executive battery. I would say it's more harvesting energy but it's also the battery because it's maybe itching a little bit, some part of the methods is not an infinity generator. And so we create this chain of carbons, which explains why the result is so dark. But it also explains the electrical conductance because the carbon chains are fully connected. So I think this might knock out a few people here, and I will probably skip most of them, but what we need is as a scientific team, we had to characterize it. So we did different tests, basically measuring three pressures that we can see here over time. And so we measure the pressure with the Newton meter. And we measured the resistance. And so we did three pressures that we can see the three peaks here. And we looked at the memory effect, because some pressure sensor would stop working over time.
And so some of the methods would not work as well over time. And it's not money, we have to find the right materials for, for example, she has this natural way of bouncing, but other materials don't have that the stretch sensor is restricted sticks and lycra for example is quite nice. But some like t shirts, do have this very good behavior. So we characterize these. And we found that we actually have a better range of resistance in different cases so the nonmovant felt the paper swingy has a nice. So it's not, you know, the next behavior. This one is just as switch of fabric. This one is interesting because it has a high resistance which makes the sensor uses less, less intensity due to work. So there is a question does overtime to account, like, the accumulation of body oils in washing. That's a very good point. We talk about that a bit later, but. Indeed, we have to wash the magic of su they are not fact before. Otherwise if there is any, like, oil on the tech side, the printer ization won't work. In normal scientific lab they will use
ultraviolet in the materials before
I go on. Also, if you want to improve your material you can do with
pure water that it was distilled
in those process that I just mentioned like UV and alcohol
So the degradation, over time, can be stabilized. So, if you wash it a few times I think it was something between five and 10 times. There's a moment when it will decrease the, the behavior of
overtime after a certain amount
of washing it will stabilize. Now, already, I haven't tried when we trained attacking the thick side with UV like sun exposure. And again, this, this kind of preparation so you have to, to attack it with me and then it stabilizes, and then you can release it to your customers if you say
also that museum exhibit. A lot of human.
That's true. That's true. So, I guess, human origins didn't really affect it so much
and free shrink t shirts, I'm not sure what you mean like examples of materials that we could use Yes.
Yes, It was genes. So genes were not very precious and city ostrich sensitive.
But I guess you should take it in diagnostic.
I won't go too much into details of these characterizations. If you're interested, feel free to ask me more questions. Let's talk about design methods, because I think it's the most interesting part for craft making less question. The same process, having to treat the material, so that the fabric is stable between washes. Yes, that's I guess when you buy a textile that is already died like probably this, it was pre processed before it was really, it makes it so this is an idea.
we made this interesting way of giving a functionality and electrical functionality to fabric in 30 reading, but we just replicate mostly what exists is made by knitting and other people are also by video sometimes, which I don't think he's as good as the as Unix, which is really the best in the industry, except our material.
you could say, all right, It's a bit like copper, the
blank PCB materials, copper is great for attorneys but it's better when you give it a structure like. You can create circuits, or in our case we can even create sensitive path in this. So when you get the possibilities. And we're inspired by traditional techniques such as shibori here. Kind of a Thai traditional taking from Japan. It's interesting because those very simple ways of hiding the thick side from the Polymer. And you can see the white part here is not functionalized, and the black part has this superpower of conductive and conducting electricity. We can also make gradients. As you can see, it's kind of nice. So we got the rise deep again, one good details on that. But yeah, you can see a little bit the region. At the top right. Another interesting traditional technique could attack, you can sorry, also from the, from Indonesia was another one, the one is interesting because you can functionalize just fibers. And there are some cities. Some people. When you could predict in Berlin, who found a very smart and easy to use this kind of mix of fabric that is functionalized, or just dark or white. And, and you can, if you have a machine that weaves sorry the spins textile,
you can have for example, a weight car, and a black
thread that rotates around it. That is turn around. And if you densify. The black thread, you can have dark areas. And if you don't, if I can have mostly white area. And if you do that in a smart way.
You can anticipate
where you should have been areas or where you shouldn't have an image in this picture here. You can see as a thread in the rest of the order. So this zigzag shozy, and you can say, I want this soon to be dark. These go into the dark and so on and you can create this triangle. So they created the software they lose, making your own thread and controlling the weaving machine. So that you can create patterns, and you could create functionalized patterns. So we tried different fibers like lean in sync and a few others that work really well. But it's not super easy to teach that you need some chicks to some techniques to make it without the dreadlocks, because then your fiber is messed up. But, yeah, we work with his gaze project Hello is the full name. If you are interested.
They have is to do Hello, sorry, so you will say,
another interesting technique from Indonesia quickbasic basically uses wax to mask the premiumization. And this wax can be removed after one, so you can do several steps of functionalisation functionalization. So we did some simple tests with this you know shows exactly, and looked at how the conductance works between two points and how it's isolated between two areas that should not be connected, and we can see that we have, mega ohms. We really didn't do that very quickly but when you have mega ohms, it's pretty much isolated. Whereas, if you have two zones that are in the same area like into. They are kind of conductors, you can use that as a center.
what is the difference between your next.
So who is not excited it's a plastic that happens to have this high conductance I think it's originally made from
Isolation so it's basically conducting electricity but another way.
Reject polarization, as
we just saw the uniques is really nice just to finish,
which is really nice because it has this. They have two main
kinds of exams when you strip seven, which is also pressure sensitive but not as nice. The other is woven. So the first it's kind of like lycra, and the other is moving, sorry not moving, it's actually. And it has this nice z pressure and behavior, kind of bouncing and have nice range of resistance a bit of range then, the last bit of that as it's not the next day, but you should wear it is really wearing plastic you don't really want that. Second question. Yes. So, somebody says, I really don't like for you there ization we tried a few
share some more details if interested.
So you so you always have to try it a few samples at the beginning and then you see what works, and you see how each method, you'll need usually something between 30 minutes and 560 minutes. If it doesn't work after 60 minutes and it works. You can see visually if you start from a white material it should become almost black or dark gray.
One more question,
not use video.
So we actually haven't. This is a work in progress we haven't done it to the studio he knew Lowe's. And basically making patterns of woven textiles, that have either functional or non functional fabric in for example here you can imagine this triangle could be a pressure sensor or capacitive sensor, but you can make any kind of
shape. So we saw with
chabrier shrubbery are
fairly random kinds of shapes. But if you want to make it in a scalable way. You could also have that kind of approach, where you will prepare your, your fiber events, and then you we with Dell machines that do it really fast and really well. So I think I was here. This is a little bit outside of the, of the functionalisation that were talking about but this is still a country. You should take the classic copper textile that you can buy, which is usually made from isolating like electromagnetic waves, you can find that on less EMF Comm. I think the people who want to isolate electromagnetic frequencies. And so this textile is pretty much a quarter. On top of polyester. And you can actually the same way as you would a normal PCB. So in our case we used. And we found that if you do that, you can create secrets. And once you have your chickens happy, then you can add the
I see that I speak a look, I'm going to go fast. In this case it's a quick. It's a simple stretch since also stretched horizontally, this resistor will vary, we change any trace key, the other one does. Here we need a pressure sensor, which is somehow taking advantage of the, of the fact that you can Fern your circuit that is again a hybrid circuit. So it has this conductive part that we come in contact with this season. And then you fold it again, this other conductive part will be on the other side so you have the sandwich. That is entirely made up with the conductive and the resistance or resistance. You can make your precious metal. So we looked at the Microsoft results but I will micro results. But I will keep that. Just to say that some of us really functionalized well in the synthetic don't
talk about that.
Some of the philosophical take away from this project is. I didn't have the background to understand how to do this kind of functionalisation, and I've been just asking many people, people in hackerspaces people in academic conferences and basically This one wasn't impossible if I didn't ask people in the conference who told me hey yeah I know someone who does the same, they can help you. This is a quote from Irani. Another friend from the bush from the, from the Excel community who say in a tip for, if you can, no sorry this is my bed. When it's from me, if you can open it, you don't own.
Again this is by this open source movement.
And that's the quote from uranium tools and materials are never neutral, and this is Shelley of use when you look at those machines, let's say, for people who make music like a Pro Tools, set of course.
Whereas open source tools can do the same.
If you look at scientific tools like,
oh, embroidery machine right now, you should look at on Twitter, this could go on living living, he's not he's a guy from the processing community, and openframeworks. He's been making an embroidery software that allows you to make custom shapes from processing. The number of tools cost thousands to make custom patterns, and he's basically making it open source and accessible. And so if you make tools that are close sources, not everyone can use it and so he is not neutral in that. So, I'm so sorry I speak too much. Now, is going to be showing a little
application that we, together, and you want to share your screen, even if
you don't have a lot of time. Three minutes.
So just really quickly what we did with the
today show. I think people are gonna be for that as well so basically what we did was we attached the strip center to in Arduino. And then when I moved my hand up and down the Perlin noise visualization will move accordingly
to this center.
And so the information pipeline and how that works is we take the analog signals from the textile. We read it through and Arduino that I'm actually holding in my hand in the gift but you can attach it in another form, if you prefer. And those signals are connected via serial port to a f running, no GS on my computer, which then converts those into something that can be read via WebSocket into p five Gs. And that will control this and you can see that if moving over here. What you will see with the whole system setup is, there's probably a nice generalization actually moving like waves, and you can check it out at this thing. I'll send it in the chat later can also Sure. I think actually had it in your choice. alternative to this that bypasses this p five zero Control F would be just use something called whip you with me. And one of our friends created a tutorial that you can check out later if you're interested to basically skip from using the Arduino to getting the signal is red, in
its greatness, you can go faster in step, but it has this problem that not every kind of problem works, you have to use it enough in order to know these kind of things are those zero does allow you to configure the processor, as you can have real hard, use the hardware, physically, so not the Arduino Uno, for example,
I have. Yeah. The difference here.
Yeah, this is the visual inspection. So basically, the stretch changes the angle of the, the orientation of the Perlin noise. And, yeah, just send the link. So, the link will be sensor connected so it's, it's not a movie, but you can use a, an Arduino and nbsp five to play with. It's known. I'm coming to you alone and. Did your question. If you have any.
This is Polly sense reverse engineering flex sensors and destroying your kitchen with chemistry for electro electrical functionalisation of everyday objects, Cedric on a thank you very much for joining us today. You know, we will have time for just a couple of audience questions maybe one or two. When one member of the audience asked about the washability of this, of this material.
So, I somehow replayed on the rail
channel. I think the, the way I mean the simplest answer is that when you make your own material, you have to wash it at the end because there's still a lot of chemicals, which are not toxic. Again, but you still need to wash them otherwise you get some kind of gray powder on your hands, and I usually wash them like five to 10 times. Something like that after, after functionalizing the material, and then it gets stable. So, It's fairly reasonable but after that. Obviously if you wash it 1000 times super hard and time, if we don't make
the time but
it's reasonably stable.
Thank you. We have a question from the audience
asking, Can you obtain the heating effect at a lower voltage, I'm thinking of the concept of plugging in a USB power bank on a cold day to heat clothing.
So that's a useful. Very useful feature I did. I would say that if you have a power bank that can provide reasonably good amount of current which is the case in general. And depending on the way you organize your, your pretty memorized circuit. It can have, for example, a long path that has a lot of zigzags, or it can be just a one big pad. So depending on the structure you can adapt the resistance of the system and allows it to work with the lower voltage but it will consume more current, it has to be somehow proportional right so it's possible, and it would need some tests, I haven't.
And we'll have to leave it there because we're just about out of time but very quickly said Eureka, where can people find more information about your work and get in contact with you.
I can send this link somewhere everywhere, it's the simplest is counter chemists on GitHub. So if you look counter chemists the github.io. There's all the documentation, if you look at also positions on hackaday. And we have a good documentation there. I think those are a good starting point.
Excellent. To drink on a thank you very much for joining us today at hope. Thanks for just one more quick announcement for attendees watching, you're invited to take the stage yourself at 1500 EDT this this afternoon. You have up to five minutes and up to five slides to share knowledge of interest in our lightning talk session. Go to the help announcements channel on matrix just before the start of the session to get the meeting link and give your talk. In our lightning talks no pre registration is needed. Cedric thank you very much indeed once again for joining us today at hope. Did you throw it right back to ground control.