USB Stretchy Fabric Connection

Make a stretchy fabric USB cable for whatever reason you like. This was a first test for me and... it worked! So the next step will be to integrate this USB connection into a shirt that I can wear, with a pocket for my digital camera, containing a USB connection that connects to the end of one of a sleeve, so that I can plug right into my laptop to download my pictures (see sketch).

This Instructable will cover the basic principle of how to make the stretchy fabric connection and isolate it. Though I take no responsibility for what might go wrong.

Step 1 Materials and Tools

MATERIALS:
- Stretch conductive fabric from www.lessemf.com
(also see http://cnmat.berkeley.edu/resource/stretch_conductive_fabric)
- Fusible interfacing from local fabric store or
(also see www.shoppellon.com)
- Conductive thread from www.sparkfun.com
(also see http://cnmat.berkeley.edu/resource/conductive_thread)
- A USB cable from your excess of USB cables lying around or from any local electronics store
- Stretch fabric (cotton jersey or similar) from local fabric store or old clothing item
- Regular sewing thread from local fabric store
- Aleene's stretchable fabric glue from www.amazon.com
- Baby powder from local drugstore

TOOLS:
- Fabric scissors
- Sewing needle
- Iron
- Soldering iron and solder
- Wire clippers
- Wire strippers
- Stanley knife

Comments

[ranex]

Asome instructable- i wonder if this technique could be used for a headphone cord extender in a hoodie or jacket, or would there be problems with resistance

[jaime9999]

two comments.

(1) USB uses "differential" signalling, like professional microphones, RS-422 (not RS-232), ethernet, modern LVD-SCSI, and other high-performance cabling systems.

On a USB connector, pins 2 and 3 carry the actual serial signal, the other pins carry power and ground. http://pinouts.ru/Slots/USB_pinout.shtml

Differential signalling exploits a nifty little trick. By carrying the signal twice on two wires, but with each wire carrying a signal 180 degrees out of phase with the other, any static or RFI interference that is picked up over the length of the line will be cancelled out at the receiving end by the receiver, which inverts one of the signals and combines them. The interference is 'added' to both signals equally, but then through the invert-and-combining process, gets deleted mathematically from the signal, sort of like how Dolby works.

While I believe the twist is not essential, it helps ensure that any interference is 'evenly' added to both signal wires.

Thus if you don't twist your signal lines, your wiring is more susceptible to picking up interference.

Solution-- Twist your conductive strips by braiding them, though you'd need an insulating layer of fabric or film or paint between them.

(2) Also, USB suggests but does not require shielding, again to reduce interference. Follow the pinout documentation above to connect the shield to the ground only at the host end. Perhaps some foil around the whole bunch of conductors? (again, separated by fabric, paper, film, or paint).

While both twisting and shielding are not essential for USB operation (there is probably error detection and correction embedded in the serial transfer protocols), you might find better performance (i.e. faster downloads) over a higher-quality (less interference-prone) serial connection. This will proably be important in RFI-noisy environments with high-speed USB2.0 devices like live cameras, hard disks, etc when performance is important.

--
and definitely consider strain reliefs. I discovered that hot melt glue gun adhesive is great for this (remains semi-flexible when re-solidified).

[dorit82]

USB signals (and every other type of differential signal) can travel using two parallel strips of copper like this fabric. the impedance of the cable is defined by the cap between the signaling conductors relative to their width. A regular USB cable also has a foil outside the data pair for extra shielding. I however see no problem with the design for short distances.

[endolith]

Remember that Hi-speed USB is 480 MHz. Not all USB transfers have full error correction and retry. If your cable isn't transmitting the 480 MHz signal clearly enough, you can lose data.

[dorit82]

Yes Hi-speed USB could easily run into problems.

[endolith]

Also, for Hi-speed USB, the width of the wires, separation of the wires, and so on is critical for the signal to get from one end to the other without errors. I'd be surprised if this works with Hi-speed devices. For low-speed signals this is a great idea, but for USB, it would probably be better to find a thin, flexible USB cable that you can sew along the cloth.

[Plusea]

WOW thanks!!! this is a big help. i'll try to take all this into consideration. thanks again!

[scienceguy]

Can you wash this? How would you?

[GorillazMiko]

Wow. Awesome Instructable. +5/5 stars. By the way, what kind of soldering iron is that?

[Plusea]

why are you interested?
:-)
http://www.amazon.com/Weller-WLC100-Soldering-Station-Hobbyist/dp/B000AS28UC

[GorillazMiko]

Dang, that's expensive. I want to buy one. The tip is really pointy. ;-)

[Spokehedz]

Trust me, you don't want to skimp on buying good tools.

Good tools make the work easier--but are not a replacement for skill.

And trust me--$40 is not expensive for a soldering iron that is temperature controlled.

This is what I work with:

http://www.action-electronics.com/wewd.htm#Wd1001

[Plusea]

if you already have a soldering iron you can also just buy the pointy tip.
but make sure you get one that fits your soldering iron!
this one fits mine, for only 3.58$
http://www.amazon.com/Weller-ETP-Conical-Tip-WES51/dp/B0002BSQQ2/ref=sr_1_4?ie=UTF8&s=hi&qid=1218761182&sr=1-4

[Plasmana]

Wow! This is a really great instructable! 5 stars!

[tcabeen]

This is terrific. I could be my own USB hub. A device on every limb. All of your projects are amazing. Don't be discouraged by naysayers. You create awesome proof-of-concept pieces that really set the mind to working on all the other possibilities that it opens. Brilliant.

[randofo]

USB cable data wires are notorious for breaking. Perhaps you may want to use actual hardware eyelet connectors to attach to each little wire since you can usually clamp them to the wire itself (which will cut down on broken connections slightly). Also, you could sew a little fabric loop onto the inside of the sleeve such that you can pass a wire through and then knot it around the loop. If you do this and leave a little extra room for slack on the end of the wires, it will keep tension off the connections themselves and in theory make them more secure. I'm sure that the stretchy fabric glue works really well for what you're doing, but have you ever tried using liquid latex as an insulator? I've gotten it on clothing before and can't get it out no matter how much I wash my clothes or pick at the spots (and it's stretchy also). I think this is very cool and very well done (as all of your Instructables are), but I must ask, why would you want to turn yourself into a USB camera cable?

[Plusea]

thanks for all the tips. i'll consider hardware eyelets and latex in the next version. and as to why? the idea came from the repetitive act of taking pictures at one end of the room, then going to sit down at my computer at the other end of the room, looking for the right USB cable, finiding space for both the camera and cable amid the mess next to my laptop and downloading the images. and then i think maybe i just wanted to see if i could send a USB signal over fabric connections. maybe instead of the top i should make a really long USB connection that is permanently mounted across my room:-)

[catwood]

...and it isn't easier to simply take either the camera or memory card out of your pocket and connect it to the computer with a regular cable?

[Plusea]

or even buy a wireless memory card!

[Nabil]

And would be able to use both hands to operate the computer, and not to stay with a hand barely connected to the laptop.

[Plusea]

if you're using you computer, then your hands are close to your computer anyway. the top would have enough slack to allow you to type and move both your hands while uploading. but you are right, the more freedom of movement, the nicer! i'll think about it. thanks.

[T3h_Muffinator]

This looks awesome! the only thing I'd be worried about is strain relief. You should definitely hot-glue the leads down, and maybe even tie a knot in the leads and then glue that down. Otherwise, you just have to be super-careful when using this. It's a great idea, let me know how long it lasts, and how efficient it is! Also, does the conductive fabric have ~ 0 resistance?

[Plusea]

thanks for the tip! the 5mm wide conductive fabric trace has about 60 Ohm resistance over 30cm. There are some pictures of me measuring it (with the terrible radioshack multimeter) in steps 3 and 6.

[T3h_Muffinator]

So..... for data transfer, I highly suggest investing in conductive fabric that has lower resistance. USB operates at TTL levels, and although your resistance is not enough to disable communications, it doesn't help. This really is a great project, but in version 2.0 the strain relief and lower resistance traces would be nice. I'm currently working on an e-textile based project, so once I post that your criticism/tips would be greatly appreciated!

[Plusea]

i'd like to keep the connections stretchy. so maybe the solution would be to use wider strips of stretch conductive fabric (twice as wide = half the resistance, about).

you got me very interested in creating version 2.0. i'm away now for a while but will already start planning solutions. and will post an Instructable as soon as i get back to the internet.

and please mail me when you post your e-textile project!