tend to have an increasing resistance across distance and are great for making potentiometers and location sensors. Piezoresistive fabrics are often also resistive across distance (x,y) but have a resistance that decreases under pressure (mechanical stress) through the material (z). These materials are great for making pressure, bend and often stretch sensors. There are a range of resistive fabrics available on the market, often sold for anti-static and electromagnetic field (EMF) shielding purposes.
Here are some of our examples made using the resistive and piezoresistive properties of fabrics:
Fabric stretch sensors >> http://www.kobakant.at/DIY/?p=210
Simple pressure sensors >> http://www.kobakant.at/DIY/?p=232
Piezoresistive Fabric Touchpad >> http://www.kobakant.at/DIY/?p=3223
Squeeze sensors >> http://www.kobakant.at/DIY/?p=3175
One range of piezoresistive fabrics are made by coating regular fabrics in an inherently conductive polymer. These are patented processes and so far I know that Eeonyx and Panipol are two companies producing such polymers. Marktek retails EeonTex fabrics.
>> http://www.hitek-ltd.co.uk/ (UK)
>> http://eeonyx.com/ (USA)
>> http://www.marktek-inc.com/eeontexconductextiles.htm (USA)
>> http://www.panipol.fi/ (Finland)
Eeonyx is a company that has developed a propriety coating system with which they can coat almost any fabric (wovens, non-wovens, felts and knits of polyester, nylon, glass, quartz, spandex, polyolefins, and aramids) in an inherently conducting polymer (polypyrrole, PPY).
The coating uniformly covers the individuals fibers of the fabric, making them conductive/resistive and also black or dark gray, but the feel of the fabric itself remains pretty much the same as the coating process barely affects the strength, drape, flexibility, and porosity of the starting substrates.
EeonTex fabrics are customized for desired electrical resistance, thickness, porosity, strength, stretchability…
Depending on the base fabric, EeonTex fabrics can possess surface resistance between 10 Ohm/sq and 10 billion Ohm/sq.
Unfortunately Eeonyx does not supply free samples or small sample orders any longer.
But HITEK now sell Eeonyx fabrics in small quantities (1m)!!!
Non-woven fabrics for pressure sensors
Stretchy fabrics for stretch sensors
The numbers in the first image correspond with the material data in the second image.
Passed on to me from Eeonyx.
A knit fabric from green/white yarn mixed with a restive thread.
>> http://www.et-esd.de/ (DE)
>> http://www.all-spec.com/1/viewitem/A205/ALLSPEC/prodinfo/w3path=cat (USA)
This fabric sold by LessEMF has resistive fibers woven into it in a diamond pattern. Unfortunately this fabric is not able replace
Unknown Black Fabric
A black woven fabric with a white non-conductive backing. It is sensitive to pressure, about 200 – 30 Ohm per cm, depending on how hard I pressure the measuring points into the fabric.
The following stainless steel and polyester yarn also has piezo/resistive properties.