Articles

Conductive Thread, Soft Circuits, and Wearables (E-Textiles)



hi I'm Sonya with AK robotic and today we're gonna be working with conductive thread to assemble a basic soft circuit I'm going to be working with the components from AK robotics so Abel LED starter kit which includes needles a coin cell battery a coin cell battery holder and a spool of conductive thread the LED and the starter kit is a self blinking LED and the one that I'm using for this tutorial is just your standard LED that you can find anywhere so conductive thread is basically what it sounds like it's thread that allows electricity to flow through it it's spun from stainless steel that's about eight microns thick and it does have a resistance even though it allows electricity to flow through it it does have a resistance in which is something you should be aware of this conductive thread has about 30 ohms per foot and that's something to keep in mind or depending on the circuit that you're gonna build if you need to have a lot of space between your components that's gonna add up but if you don't then it's not really something you should worry about I'm gonna be making my soft circuit on this patch of felt and as you can see I've made some pencil marks where I'm going to put my power source and the LED you don't have to do this but it just makes things easier so the first thing that you do when you are sewing is you got to thread a needle and the thing to keep in mind about conductive thread is that it frays easily because it's got that stainless feel in it which can be really difficult to get the thread through the eye of a needle if you've got quilting beeswax that's a good thing to use another tip is to use a pair of scissors to cut off the ends of the thread which gives you a nice blunt end to put through the needle or you can just roll it between your fingers like I'm doing so because conductive thread is kind of more stiff than regular thread normally you would what you call double thread the needle where you would pull it and it would be two pieces and you'd knot it here and so that way with conductive thread one good thing to do is to make it a single thread if you just twist it a little bit and that'll be fine to work with so the first part of my circuit that I'm gonna show is the power source so the first thing that needs to go down is the coin cell battery holder I'm gonna do that by for securing the terminals with the conductive thread and each terminal is going to go to the output which will be the led so positive will go to the positive leg of the LED and negative terminal will go to the negative part of the LED so I'm going to start with underneath the piece of felt I'm going to be careful that the thread doesn't go all the way through and then just tie a knot at the end of the piece of thread and like I mentioned before conductive thread is really thick so if you go one knot or double on the knot that's enough to keep it from going straight through the piece of felt some people like to secure their components with a dab of hot glue to keep them from sliding around as they're trying to sew and that's a really good thing to try I'm not using that for this tutorial so I'm just gonna loop around a couple times the rule of thumb is to make about 35 loops as you're pushing through is your piece of thread make sure that you don't pull on just a needle because you will undo the thread that you put through your needle so once you get your loops through with the terminals kind of just next to the terminal make a couple of loops of the conductive thread because you need to make a contact point for the path of your circuit so at this point you can cut the thread there and make a knot this is how I like to make a knot if you use a needle you can make sure that the knot is as close to the piece of felt as possible this is just something that I picked up when I spoke when you make your knots with the conductive thread make sure that you cut off any dangling pieces the thing to keep in mind about conductive thread is that it's kind of like the wires of your circuit so you want to make sure that two pieces that are not part of the same path don't touch each other because then you get what's called a short-circuit and then your circuit won't function and that's not so now we're going to sew the other terminal of the battery holder and like before I'm going to start from the bottom don't forget to put a knot at the end of your piece of thread otherwise you're going to keep pulling and it's just going to go straight through trust me I've done it before so you're just gonna make the same number of loops that you did for the previous terminal as you go along you might be tempted to speed up but because conductive thread is doesn't have the same properties as regular thread you might want to take your time and just make sure you're paying attention because conductive thread has been known to snap I'm gonna make this not to finish up this side using the needle again to help me make my knot making sure to cut any straggly ends so now we've secured the battery holder now I'm going to take our LED and put it into the circuit so LEDs have polarity a negative side and a positive side the shorter leg of an LED is the negative side and the longer leg is a positive side and there's also a flat end on the plastic that'll let you know that that's the negative side I'm going to take my pliers and I'm going to curl the length of the LED which makes it really easy for the conductive thread to sew around and secure the LED and as you're doing that make sure that you keep track of which is the negative and which is the positive but even if you forget which one was a short leg and which one was the long leg you can look for that flat side on the plastic so the polarity of the LED has to match up with the polarity of the battery make sure that the negative goes to the negative and the positive goes to the positive I'm going to take my conductive thread and I'm going to secure the LED and to do this I'm going to sew around the curl of the LED leg always making sure to not the end of the first stitch I'm gonna cut a fresh piece of conductive red because this one was getting really short conductive thread is a very useful material so if you have little pieces like that save them because they might come in handy later so now I'm sewing the other positive terminal of the led and I'm using the same method that I used with the negative leg trying to make as many loops roughly around 3035 works and you want to make sure that the loops are tight around the legs so that things are kind of real snug and there's close contact so now our components are secured on the piece of felt so now I'm going to show you a few stitches that you can use in your circuit the first stitch is your basic in out around the fabric stitch so I'm going to start at the contact point of where the thread that was sewn onto the battery terminal ended and before I do that I'm going to go ahead and not the end of spread two knots is always good for safety so your basic stitching you just go up and back into this red just in out in and out and each stitch is basically the same length so the ones underneath the felts are about the same length as the ones on top of the felt so then you end up with just basic stitch so I'm going to do the basic stitch half way through the signal path and the signal path is connecting the negative terminal of the battery over to the negative leg of LED and this basic stitching is fine for when you have a short circuit path like I do here now I'm going to show you sort of the kind of stitch that you want to do if you want to cover a lot of ground quickly and that's just doing very long spaces between the points that you go into the fabric and out so as you can see it took me a fraction of the time to get to my endpoint then the basic stitching did so I reached the ends and I'm we're going to knock the conductive thread using my favorite method which is using the needle so as you can see the basic stitching it's tighter and this other stitching it just it's a it was a lot faster to to do and the stitches are longer a lot longer than the basic stitching so now I'm going to sew the other side of the circuit the positive terminal to the positive leg of the led let me get a nice and long piece of conductive thread for this one I also like to twirl the thread between my fingers to kind of keep it from fraying get it through the eye of the needle and you can also add the knot at the end of the thread before you even start sewing that's a good rule of thumb double nodding because that's always a good practice so just like with the other terminal I'm gonna start at the contact point that I made so you can see all the conductive thread kind of clumped together on that end I'm gonna start making sure that this new piece touches with the old piece that's already there so this kind of stitching that I'm going to show you for this side of the circuit is for when you have part of the fabric that you don't really want to see stitching on so the side that's facing you is going to have very small stitches that are visible but on the back side it's going to have longer pieces and that's where most of the stitching is gonna hide so since I'm on the top face I'm gonna make a very small stitch and kind of my pliers so on the back of the felt I'm gonna make a longer stitch and on the front side I'm going to make a shorter one and just like that we're gonna continue until we get to the LED and what makes a short stitch and what makes a long stitch it's just how close you put it to your last point and for the purposes of this video my stitching isn't very nice looking so when you're working on your project you can take the time to make sure that your stitching is really nice-looking or makes a pretty pattern which is part of the fun of wearable projects is that not only are they techie but there's that creative element to it so it's like you're combining arts and crafts with tinkering so I've made it all the way over to my led and now I got to make sure that that path that stitching ends directly in contact with a conductive thread of where I want it to go so you could even use this piece of conductive thread to make even more loops around the legs of the LED which have been curled because just like with regular circuits you want to make sure that your circuit loop is closed so the pieces of conductive thread that need to connect need to overlap and you need to make sure that they're making good contact with each other so now we've finished our circuit you've got the power source which will be over here and the LED which is over here and we've made sure that we've got signal paths here a signal path there but as you can see this kind of stitching you can barely see on this side because most of the thread has been stitched on the back end see if you don't cut loose pieces of thread because this is a soft circuit that piece could end up crossing over to the other side and causing a short-circuit and what I like to do with the pieces of conductive thread that I left leave over is that sometimes you can incorporate them and sew them into paths where you feel like you need to reduce the resistance so they're good for that so now we're gonna complete our circuit by actually inserting the battery into the battery holder now the battery also has polarity and the top side has a plus sign and it's a plus ID and the bottom which has no writing on it is a negative and as you can see on the battery holder the negative side goes on the bottom so it's like facing up it's almost like heads and tails on a coin and as you can see we've closed our circuit and the LEDs lighting up so there you have it that's how you can build a very basic soft circuit using acrobatics syllable LED starter kit I hope you had as much fun as I did thanks for watching you you

5 Comments

  1. ma ma

    I'm not a good English speaker 🙏 Plz upload More video. E textile. I live in Bangladesh. i want to learn E textile. My study shows B.sc in textile my University not available E-Textile subject

    Reply

Leave a Comment

Your email address will not be published. Required fields are marked *