WORK IN PROGRESS
Exploring different possibilities to knit stretch sensors.
With Schoeller Wool
A hand knitted 3x6cm rectangle from Schoeller’s Nm 10/3, 80% PES, 20% Inox steel fiber (M869) conductive (resistive) wool. The range is between 10-5K Ohm resting and 200 Ohm when fully stretched.
Front/Back
Stretched in both directions yields very similar results
Video of sensor connected to an arduino, sending values to a Processing graph application
Video of sensor connected to a battery and an LED
Hand knitted, conductive yarn mixed with normal yarns
Hand knitted single and double rib stitch mixed with conductive yarn from Schoeller, Nm 50/2 60/40 Pes/Inox @ Euros 65.00/kg (25,000 metres/kg).
The resistance gets lower when stretched. Following is the result of simple hand stretch test.
Yellow knit: 20M ohm (laying down on the desk) – 5k ohm (stretched maximum by hand)
Green knit: 300k ohm (laying down on the desk) – 2k ohm (stretched maximum by hand)
Both of them where possible to read through Arduino analog inputs with internal pull-up. Although sometimes it does not go back to original state when released. Green knit shows much stable result.
Crochet, conductive yarn mixed with normal yarns
Mesh stitch crochet, normal yarn mixed with conductive yarn from Schoeller, Nm 50/2 60/40 Pes/Inox @ Euros 65.00/kg (25,000 metres/kg). The range is between 250-300 Ohm resting and 60-80 Ohm when fully stretched per 10 cm.
#ST3003: Double stitch crochet
Stretch test: Normal 200-230k ohm >> stretched 5-10k ohm
#ST3004: Treble Crochet with 1 stitch interval
Stretch test: Normal 120-140k ohm >> stretched 20-30k ohm
#ST3005: Double Crochet with 2 stitch interval
Stretch test: Normal 10-15k ohm >> stretched 5-8k ohm
*note: these crochet pieces does not come back fully after being stretched, so the normal state resistance differs according to how much it came back. Backing with other material to support shrinking back will help to have a stable normal state.
With Silver Plated Nylon conductive thread
Because the threads used here are intended for sewing and are much thinner, the knitting is very loose and after repeated stretching it stretches out and does not react any more. It might be able to improve this by using some regular thread to stitch the loops of knitted conductive thread to the stretchy base material at regular intervals. Forcing it back into an initial (not stretched) state.
66 Yarn 22+3ply 110 PET, from LessEMF.
117/17 2ply, from LessEMF.
From Plug and Wear
Knitted stretch sensor from www.plugandwear.com
The resistance difference is almost 1k ohm to 800 ohm. The range and original resistance differs a lot depending on how it was held and pressed at the beginning. Stretch amount is +7cm on holizontal way, + 3cm on vertical way. It was measured between right top conductive yarn and left bottom conductive yarn.
[…] How to get what you want is a rich resource for anyone working in wearable technology – whether you’re looking to to knit your own stretch sensor, […]
Do you carry fabrics? How long do they last? What are they made of? are they easy to sew? Does this fabric come in fleece? Does it come in flannel? What is the wool made of? If I were able to knit a sweater and didn’t stretch it….would it last indefinitely? How would you wash something like that?
I have so many questions…I have learned so much about diet…how important eating raw…never eating anything with a face on it…avoiding dairy etc..I’ve learned so much about GMO’s and the hazards that go with them…but never gave a thought to all the EMF that has been unleashed on us today…I love all these conveniences but am realizing how detrimental they are to our health….
Please send me any information you can I would like to know how to protect myself and my family…
[…] To detect breathing, we would use a stretch sensor placed across the wearer’s ribs, in the area of the diaphragm. Here we would be able to get the greatest range in stretch and will thus be able to better control the lighting effects. The sensor will be held with a belt underneath the garment, so as not to interfere with the visual display. We recognize that a level of comfort should be considered for the belt so as not interfere with the wearer’s experience. This was a helpful link while performing initial research into stretch sensors. Stretch Sensor Resource […]
It’s strange that the resistance of the yarn gets lower when stretched. This is different from stretching conductive thread – the harder it’s stretched, the higher resistive it becomes. Can you please explain this?
good day sir, im steve from philippines.. i would like to ask what site can i buy this knitted rectangle strech sensor.. we probable use this sensor in our project design in our school.. i hope you can buy soon.. thank you and god bless.. this is my email address if you like to email me instead.. hubertsteve1986@gmail.com.. ^_^
good day! i need help on this device.. where can we buy this device? what website? because we badly needed on our project design at school. i want some help sir. thank you and god bless. 🙁
We do not sell the knitted stretch sensors… but you can make one by simply knitting conductive yarn yourself. You can knit or crochet.. or even use knitting machines (you have to be careful with the needle gage in that case)
You can buy the conductive yarn from
http://www.plugandwear.com/default.asp?mod=product&cat_id=105&product_id=213
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