Augmenting materials with electrical properties ⚡⚗️

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Made out of anything fibrous / porous! (by "augmenting" materials)

👉 Pressure, stretch, capacitive touch, humidity, or temperature sensing?
We got you covered.


⚠️ PolySense got the wildcard award of the Hack A Day prize!










Application examples

Artistic visualizations:  

VR gloves:

CCC leggings:


We use a chemical process called in-situ polymerization (explained later).

It allows functionalizing almost anything fibrous and porous materials (natural ones like cotton or cork work better than synthetics in general).

Once polymerized, your originally non-functional material ends up with sensing capabilities:
- pressure 
- stretch
- capacitive
- humidity
- temperature (bonus: heating is also possible)


In our hackerspaces and research labs, we explored musical textile interfaces and we used a commercial piezo-resistive material (pressure sensitive).

The only good one was expensive and became hard to get because of a new exclusive contract with another company.

So with material scientists, we reverse-engineered it, and made a DIY process simple enough for the kitchen of our hackerspaces.

Illustration of the piezo-resistive effect:


The following video summarizes the process, but you'll need chemical products:
- Europe source: Pyrrole + Iron Chloride
- US source: Pyrrole + Iron Chloride

...and get a machine to mix your materials for about 1h, example:
- chemistry magnetic stirrer
- ice cream maker
- a batter mixer
- a camping washing machine
- or you can build it with a drill and a bucket for example.

Protocol summary

(adapt X to your quantity):

1) Water: ( X ) ml - fill the container so that there's about 75% of textile (but don't put it yet!)

2) Pyrrole: ( X / 250 ) ml - add it and stir it

3) Material: add it and keep stirring for 10 minutes

4) Iron chloride: ( X / 100 ) g - keep stirring for 30-60 minutes depending on the material

5) for capacitive sensors: you can repeat this procedure, or multiply these proportions and polymerization time by 2 to 5 (depending on the material too).


The process, called in-situ polymerization, is particularly unique because:

- First we soak the textile with the monomer (steps 1 to 3)
- Then we trigger the polymerization (in-situ, or in place)

This reaction creates "a kind of molecular dyeing with carbon" which has much stronger properties than a coating approach.


Sourcing the products

The chemical products were ordered from 2 possible sources:

- Europe:

- US:

Note: every material reacts differently so you'll have to do a couple of tests to get the right chemistry ratios, and the right timings...

Detailed presentation:

  • Heat Generation + Sensing

    Drix02/12/2020 at 12:17 0 comments

    Heat Generation

    We polymerized a glove, and looked if we could warm it with a bit of power, it's quite nice in winter!

    With about 0.6A x 20V = 12W (yeah, not exactly low-power), the glove went from 20°C to 53°C (= from 68°F to 127°F) in about 9 seconds (it's not very comfortable above that temperature).

    For scientific reasons, we waited until the magic blue smoke came, and it was 130°C (266°F), wait for it:

    Heat Sensing

    Of course, we don't want to burn people so we looked if we could measure the resistance variation with heat. 

    The measures are fairly inaccurate as we used a thermal camera, but the graph below gives an idea of how this Resistance VS Temperature behaves:

    If we can ensure that there is no humidity (sweat, rain, etc), it seems realistic to use the resistance measures to estimate the temperature and stop heating above a threshold (ex: 74 ohms <=> 50°C / 122°F).

  • Artistic applications

    Drix02/12/2020 at 00:54 0 comments

    A couple of artistic projects were already born out of the PolySense technique:

    - - -

    Stymphalian Birds

    Stymphalian Birds is an art installation exploring the aesthetics of a hybrid textile at the crossroads of electronics and haute couture. The textile combines traditional hand-crafted elements with digital technology, biological artefacts, and chemistry.

    Stymphalian Birds are situated at the intersection between traditional featherwork and material science, the resulting textile offers complex haptic interactions with feathers.

    - - -

    Digital Topography

    This work is already exhibited in a french museum, but the video is still in progress.

    This gif illustrates the interaction:

    ...and in this video made in our hackerspace (, we show the 1st test with capacitive sensing on our own polymerized pleated fabric:

  • Explorations

    Drix02/11/2020 at 03:13 0 comments


    We started with chemistry magnetic stirrers, but we needed bigger, so we built our own gig with a drill (left). We then tried polymerizing a pre-stretched material to see if it would help (right), but the results were not particularly convincing...

    Augmenting existing materials


    This is probably the simplest, but most unique to this process, we don't modify materials mechanically. This zipper used to be white, but the polymerization made it black. Here we use the constant resistance of the augmented material to measure how much the electricity has to travel depending on the closed / open state (250k => 600k). Obviously, it's a continuous measure, so this is a bit like a flexible potentiometer:

     - - -

    Kinesio tape

    This is a sticky tape that can be purchased in most pharmacies for sprain or dislocation, it's made of cotton and glue to stick to the skin. As illustrated below, it can be used as linear slider (a), pressure sensor (b), xyz touch pad (c) and stretch/flex sensor (d).

    Note: an academic paper about it was published at the Augmented Humans Conference.

     - - -


    As seen in the demo video, we can functionalize stretchable materials, the top pictures show the range for a simple textile elastic: from 120 Kohms to 1.2 Mohms when stretched twice.

    In the bottom picures, we can see a special thread that we polymerized: it has a copper core and a textile shield, which became piezoresistive. We can thus measure the pressure at the intersection: the resistance goes from 8 Kohms to 2 Kohms with maximum pressure.


    We tried various ways to create controlled patterns.

    Batik, a traditional technique from Indonesia, uses war to block dyeing process, and it works well for our polymerization too (see bottom right pictures + next section). The only trick is that wax needs a bit of fat to make it crack less.

    We also used quick prototyping approaches, such as 3d printing (top pics) or hot glue (bottom) on textiles, and they both work but sometimes involve boiling to remove the mask.

    Finally, we made stencils with laser cut acrylic (top pics) and the result were fairly impressive. Depending on the textile we could make 1mm traces (with 0.1mm cut in the stencil).


    That's where it gets exciting. If you take a "classic" conductive textile made out of  silver or copper (cheaper), you can etch it with vinegar (or with the iron chloride of our process).

    You can mask it with all the techniques mentioned above, then you get a flexible PCB!

    The good news here is that you can also polymerize some parts of this flexible PCB, and get pressure sensors for example - see 'c' below. By folding it, you can measure the variable resistance between 'a' and 'b':


    Cheap USB microscope give pretty good images now, so we looked at what polymerized, and what didn't. In picture 'a' we can see vertical thread that stayed white, probably because it's synthetic, but also possibly because it's "masked" when this textile is not stretched.

  • Reverse Engineering

    Drix02/10/2020 at 22:59 0 comments


    While exploring musical textile interfaces, we used the piezo-resistive material below (dark grey):

    It was expensive and became hard to get because of a new exclusive contract with another company, so with material scientists, we reverse-engineered it.


    First, we observed a reference sample with a classic microscope:

    💡Trick: to check if it is a classic coating (thick paint) or a more sophisticated approach (like our polymerization), the best technique is to use liquid nitrogen to freeze and break the textile. Using a knife / scissors would potentially spread the eventual coating so it would not allow seeing the real inside.

    Raman Spectroscopy

    After checking the process type, Raman Spectroscopy is quite practical to try identifying materials. Here we compared our sample with similar ones from our database.

    This magic tool shoots a laser pulsed at various frequencies and it measures the energy bounced, which allows creating a spectrogram (see bottom right).

    Note: a possibly more intuitive illustration is the acoustic property of objects around us, a phone and a mug would resonate at very different frequencies...


    It was fortunate, but this material science team happened to know several similar processes that could do this functionalization, so after trying several we worked on simplifying the simplest:


    One of the tools they use looks like a nuclear weapon, it took years to build it, and it definitely does't fit in our hackerspace kitchen, but next time we have to play with it!

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Stefan Krüger wrote 05/19/2021 at 08:38 point

Thanks for your great documentation!
that is really an interessting e-textil-concept and i like to try it!
in your yt video you are using a *camping washing mashine* ?

  Are you sure? yes | no

Drix wrote 05/19/2021 at 15:47 point

If you're limited by space or budget, this portable machine should be good:

The ultrasounds might actually improve the results!
Keep us updated if you try it!

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Petar Crnjak wrote 01/08/2021 at 20:48 point

I love this! Do you think it would be possible to make something like a VR glove you made but for the whole arm? So something like a mocap suit? 

  Are you sure? yes | no

Drix wrote 01/09/2021 at 02:42 point

There might be some drift, but it worked for the legs (see 3rd gif from the top) so it should work for the arms ;)

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pauline.vierne wrote 12/08/2020 at 15:43 point

Hey, congratulations for the price,

I don't know how many others have reproduced the process you describe here,
For me it has been for sure exciting and satisfying to make our own piezoresistive materials for e-textiles, though I still have many things to keep trying (still documenting too)

Still, I wonder how clean is really the residual water ? It smells of iron to be honest. What if, widely used as democratized practice, we start to pour this in local water systems ? Is it safe ?
I also observed that sometimes black particles remained floating. This was true when I added too little textiles for the amount of water. I filtered as much as possible so as not to let it escape into water system, but what was it ? According to some research, polypyrrole could decontaminate waste water from heavy metals ( ) , do you know if this talks about the same thing ?

In general, I believe it would be good to mention any environmental impact for such DIY cooking, positive / negative / unknown, as this may need to be taken into account towards more sustainable practices (in e-textiles and others).

Thank you !

  Are you sure? yes | no

Drix wrote 12/19/2020 at 18:53 point

That's a great point. From my understanding the result of the chemical reaction is safe, it even passed the tests on skin cells for bio-compatibility. It's basically carbon and iron, which are available in the nature, but of course it's not a good idea to put tons of this in rivers, as well as dyeing factories are horrible for the environment.

Now the publication that you found is adding a surprising application of polypyrrole (PPy). If I understand well it could apparently attach to heavy metals to make them easier to filter, which suggests that PPy would be easy to filter. Great news!

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bobgreenwade wrote 11/11/2020 at 17:12 point

Wow! This is impressive! It may even be patent-worthy!

How is it for sensing vibration? Could it be used to turn fabric (spandex) into a throat mike?

  Are you sure? yes | no

Drix wrote 11/11/2020 at 17:30 point

Hey, the idea was actually to make the process as open as possible, but I appreciate your enthusiasm ;)

For small and fast vibrations I would try a piezoelectric sensor (not piezoresistive) or maybe triboelectric.

That's an interesting challenge!

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Ahmed Hefnawi (Volta) wrote 03/01/2020 at 16:53 point

It's a very exciting project especially the heat sensing and overall electric capabilities that you get out of it and I like the detailed process of reverse-engineering as well as testing that you shared, thank you :)

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Drix wrote 03/01/2020 at 22:23 point

Thanks a lot for your comment!

  Are you sure? yes | no

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