Sensitive Fingertips

Pressure sensors on your fingertips intended for use by children and their piano teachers to visualize the difference between "p" piano (soft) and "f" forte (hard). The pressure sensitive layers of fabric in the fingertips of these gloves are stretchy so that they can fit tightly.
The sensors are made from stretch conductive fabric and piezoresistive Eeonyx fabric. The glove is connected to the Arduino via metal snaps and a fabric cable made from sewn conductive thread traces.

HOW THE SENSOR WORK
The piezoresistive effect describes the changing electrical resistance of a material under mechanical pressure. Eeonyx coats a range of anti-static woven and non-woven fabrics in an inherently conductive polymer, giving them piezoresistive properties. By adhering two traces of stretch conductive fabric parallel to one another across the fingertip and then attaching a piece of piezoresistive stretch fabric on top of these, one is able to measure the change is resistance between the two conductive traces when pressure is applied through the piezoresistive material.

Sensitive Fingertips is a collaboration between Dr. Umida Avloni, director of the Avloni Academy of Music, Dr. Jamshid Avloni from Eeonyx and Mika Satomi and Hannah Perner-Wilson from KOBAKANT. This is the first working prototype, things to be improved include:

• Integrating the sensors better around the shape of the fingertip, possibly knitting the glove and including conductive and resistive yarns to do so in a three layer knit
• Making sure the sensor reacts well not only to holding down pressure, but to the tapping of piano keys
• Making sure all this works on the scale of a child's hand
• Improve the software and visualization side

More information about the techniques, materials and tools used in this Instructable can be found in our KOBAKANT database How to get what you want >>
http://www.kobakant.at/DIY

Videos

Step 1 Materials and Tools

MATERIALS:

• Eeonyx SL-PA coated piezoresistive stretch fabric (RL-5-129) from http://www.eeonyx.com
• Stretch Conductive Fabric from www.lessemf.com/fabric.html
• 117/17 2 ply conductive thread from www.lessemf.com/fabric.html

or www.sparkfun.com

• Fusible interfacing from local fabric store or www.shoppellon.com
• Aleene's Flexible Stretchable Fabric Glue from http://www.amazon.com/Aleenes-Flexible-Stretchable-Fabric-Glue/dp/B0001DSCQ0
• Metal poppers (snaps)
• Jersey stretch fabric
• Non-stretch fabric
• Regular thread
• 5 x 4.7uF capacitors
• 5 x 50K ohm resistors
• Solderable Perfboard with copper line pattern from All Electronics http://www.allelectronics.com/
• Male and female headers from Sparkfun http://www.sparkfun.com/
• Arduino USB board from Sparkfun http://www.sparkfun.com/
• Computer running the following software:
• Arduino software free for download from http://www.arduino.cc/
• Processing software free for download from http://processing.org/

TOOLS:

• Sewing needle
• Sewing machine
• Scissors
• Pen and paper
• Iron
• Cutter knife
• Pliers
• Soldering iron

Comments

[masterzeb318]

does anyone no how much this cost?

[Gundanium]

Where did you get the 50k Ohm resistors? They seem to be hard to come by.

[Plusea]

they were in the lab that i was working in at the time. i'm guessing they came from RS electronics (the european digikey equivalent).

[Gundanium]

It looks like those resistors in your photo are actually 56k instead of 50k if I'm reading the bands correctly. green = 5, blue = 6, orange = 1e3x => 56000 or 56k ohm.

How accurate do those resistors need to be?

[Gundanium]

Hi Plusea,

I just want to say I'm a big fan of your work and your Instructables have helped me get a start in integrating soft circuits into my projects.

I was wondering if you could explain how you attached the Eeonyx fabric to the finger tips to complete the sensors. Here's a few questions in particular...

Is that conductive thread in the picture?

Did you use fusible interfacing to make the conductive fabric strips underneath adhere to the Eeonyx fabric?

Thanks and keep up the great work!
Gundanium

[Plusea]

i didn't use conductive thread to sew on the patch of eeontex, just regular thread.
i did use fusible interfacing to adhere the conductive fabric strips!

:-)

[Gundanium]

So the conductive fabric and Eeonyx patches aren't connected to each other and are just sitting on top of one another?

[Plusea]

exactly. you don't want a direct electrical connection between the two conductive fabric strips, instead you want the eeontex to bridge the gap and then because of its piezo-resistive properties (decrease in resistance when pressured) it will act like pressure sensor (FSR).

[Gundanium]

Ah ok. Thanks! Was there a reason why you didn't attach the Eeonyx patch in a way such that it had a secure connection to the conductive fabric strips (still acting as a bridge)?

Can't the Eeonyx patch deform (while the finger isn't pressing on something) and detach from one or both of the conductive fabric traces causing an open circuit?

[Plusea]

the eeontex was very sensitive, even to stretch, so i wanted it to be as loose as possible. but i always recommend trying things and testing them for yourself as it very much depends on implementation and what you want.

[Gundanium]

That makes sense. Thanks for the help!

[UltraMagnus]

where can you buy the Eeonyx fabric? they don't seem to sell it on their website.

[Plusea]

email them and ask for samples or to purchase small amount!

[game_hero]

How are things going on the next version of these gloves? some students at the Antwerp University have come up with some drumming gloves recently, what do you think Plusea? ----------link------------ http://www.psfk.com/2010/06/wearable-drum-kit-played-by-tapping-fingers.html

[remork]

Hi

excllent tutorial!

But I do think there is an error in the Arduino code being used to visualise the data: I get this error when I compile in Arduino:

o:  In function 'main':
undefined reference to 'beginSerial'

Could it be a typo somewhere?

[Plusea]

Arduino updated its syntax so the new correct code is now:
Serial.begin();

:-)

[remork]

aha :-)
It's all about spelling and syntax!

Thanks :-D

[peque_percusion]

fantastico.......

[spacenookie]

extra " in your url to kobakant/DIY

[Plusea]

thanks for noticing!

[talk2myshirt]

Another greatly inspiring project straight out of your kitchen :) Just one remark: I think at step 3 the trace should be 5mm wide and not 0.5mm which would be quite a challenge to cut and handle ;)

[Plusea]

Vielen Dank Erich! werde das gleich korregieren.

[endolith]

Is the response time fast enough to use it for finger drumming? :)

[Plusea]

ahhhhh.... maybe not yet. but this is what we should be aiming for...... in a next version:-)

[kalantari]

Hi Plusea, Good job! Masoud

[Plusea]

thanks!

[scott!]

awesome!

[lemonie]

I am impressed (again) L

[brunoip]

Amazing :0

[ReCreate]

Yeah i know right? Yet another reason to get an arduino :D