Neoprene Bend Sensor IMPROVED

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About: My work combines conductive materials and craft techniques to develop new styles of building electronics that emphasize materiality and process. I create working prototypes to demonstrate the kinds of electr...
Better results and slimmer design, this Instructable improves on the previously posted Fabric Bend Sensor.

Previous Instructable >> Fabric Bend Sensor

Using neoprene, Velostat, conductive thread and stretch conductive fabric to sew your own fabric bend sensor. The sensor actually reacts (decreases in resistance) to pressure, not specifically to bend. But because it is sandwiched between two layers of neoprene, pressure is exerted while bending. Allowing one to measure bend (angle) via pressure.

To make the sensor fully fabric one can use EeonTex conductive textile (www.eeonyx.com) instead of the plastic Velostat. Eeonyx normally only manufacture and sells its coated fabrics in minimum amounts of 100yds, but 7x10 inch (17.8x25.4 cm) samples are available free of charge and larger samples of 1 to 5 yards for a minimum fee per yard.

VIDEO
To prove the competitiveness of this sensor vs. a commercial bend sensor I made a short video in which Sheep demonstrates their similarities.


Step 1: Materials and Tools

The materials used for the sensor are basically cheap and off-the-shelf. There are other places that sell conductive fabrics and Velostat, but LessEMF is a convenient option for both, especially for shipping within North America.

Velostat is the brand name for the plastic bags in which sensitive electronic components are packaged. Also called anti-static, ex-static, carbon based plastic& (So you can also cut up one of these black plastic bags. But caution! Not all of them work!)

- Neoprene 1.5 mm thick HS quality from www.sedochemicals.com
- Velostat by 3M from http://www.lessemf.com/plastic.html
- Conductive thread from http://www.lessemf.com/fabric.html
- Stretch conductive fabric from http://www.lessemf.com/fabric.html
- Fusible interfacing from local fabric store
- Regular sewing thread from local fabric store

TOOLS:
- Pen and paper
- Fabric scissors
- Iron
- Sewing needle
- Possibly pliers for pulling needle through neoprene

Step 2: Stencil

Print out a copy of the Neoprene Bend Sensor Improved PDF and cut out the stencils for the neoprene, Velostat and stretch conductive fabric tabs. Trace it twice onto your piece of neoprene and cut these out. Now mark the inner stitches and placement of conductive fabric patch onto these cutouts. Caution! The tracing should be identical and NOT mirrored.

Download Stencil PDF >> http://kobakant.at/downloads/stencils/neoprene-BS-improved.pdf

Step 3: Ironing

If you have not already fused interfacing to one side of your stretch conductive fabric, then youll want to do that now.
Now place the two pieces on top of the neoprene cutouts and fuse these together with an iron.

Step 4: Sewing

Thread a needle with about 50 cm of conductive thread (do not take it double) and stitch from the side into the first marked stitch hole and then make the four stitches and at the end connect to the stretch conductive fabric tab with at least five stitches. Cut the thread and repeat on the second piece of neoprene.

The reason the stitching on both sides must be identical is so that when they lie on top of each other (facing each other) the stitches crisscross and overlap in one point. This has the advantage that the stitches will be sure to cross (make contact at these points) and second that the point of contact is as small as possible. Ive found that if the conductive surfaces are too big that the sensitivity of the sensor is no longer good for what I want.

Step 5: Closing the Sensor

Start sewing around the edges of the two neoprene pieces. Make sure to displace them by the 1.5 cm marked on the stencil. And dont forget to insert the two pieces of Velostat before closing the sensor all the way!!!

You can add more or less pieces of Velostat to control the sensitivity of the sensor.

Step 6: Sheep's Demo

You are finished. To demonstrate that it works simply hook it up to a multimeter and set it to measure resistance (Ohm). Bend or press the sensor and the range should lie between 2K and 200 ohm.

You can also hook it up to your computer and graph the input. For this you will need to follow the instructions in the previous Fabric Bend Sensor Instructable (see step 7) >>
https://www.instructables.com/id/Fabric_bend_sensor/

Let me know if you make one, I'd love to see some photos.
Enjoy!

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34 Discussions

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BowMan831

4 years ago on Introduction

That's pretty impressive accuracy for a home made sensor. nice work!

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ryerex

4 years ago on Introduction

Seattle Fabrics has 2mm Neoprene which worked for me.

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raj_at

4 years ago on Introduction

why do you need both neoprene and stretch conductive fabric won't they both basically do the same thing?

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Capt.Phil

7 years ago on Introduction

Hi, Was wondering if there was any household material that you know of that would provide the same function as velostat? If i'm right in assuming that we are using a conductive material to place inbetween the conductive thread would something like tin foil work?

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PluseaCapt.Phil

Reply 7 years ago on Introduction

that is a great question. unfortunately i don't know of a household material that can replace velostat. aluminum foil won't work because it does not have piezoresistive properties (changes electrical resistance under pressure). but you could try using a porous material that allows for more or less contact depending on how hard you pressure it. let me k now if you find something that works!!!

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Capt.PhilPlusea

Reply 7 years ago on Introduction

I live in the uk and need only a small amount of velostat (or substitute). Do you know whether something like this would work? http://www.maplin.co.uk/Module.aspx?ModuleNo=396629

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PluseaCapt.Phil

Reply 7 years ago on Introduction

i have not had luck with the silver/transparent anti-static bags. you want to find a black one. try ordering linqstat from caplinq. it is the same as velostat.

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Capt.PhilPlusea

Reply 7 years ago on Introduction

Thanks for your quick replies, I will try and get hold of some soon and let you know how it all goes.

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Capt.PhilCapt.Phil

Reply 7 years ago on Introduction

I managed to get hold of some (very similar to but not actually) velostat and after following your schematics managed to come up with sensors that work but there opperating in the Mohm range....not really what I want. Any ideas why this might be? just due to the anti-static material?

I am trying to build a flex sensing glove to control a robotic hand that I am building currently. So any ideas would be greatly appreciated.

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PluseaCapt.Phil

Reply 7 years ago on Introduction

yes, i think the high resistance range might likely be due to the velostat/substitute. try using conductive fabric (or aluminum foil) instead of the conductive thread on either side.

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NicOmbra

8 years ago on Introduction

Could you attach these to an electric key board's keys to play music by bending your fingers?

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azdelslade

8 years ago on Introduction

hi, first off, thanks for the brilliant instructable! i made one of these with all the components you listed here, neoprene and actual velostat. i can get readings off of my multimeter fine and change an led with a battery fine, but when i hook it up to my lilypad on a1 or a0, I only see changes between 1023 and 998, which is not much. I tried loosening up the stitches and using digital 5 as a power source instead of +, but it doesn't seem to help. Any suggestions? When I put my multimeter on 200k i get readings between 20 and 0.5. I tried adding 10k, 1M and 10M resistors, but that still didn't improve the sensitivity. I also tried adding another piece of velostat.

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azdelsladeazdelslade

Reply 8 years ago on Introduction

I was able to get a decent reading by making a voltage divider circuit, after looking at this lilypad flex sensor example: http://mtifall09.files.wordpress.com/2009/12/rhinoglove.pdf

 Hello Hannah, 
Greath idea and Super instructables.
Have you some Ideas where is possible to find in Europe some sheets of EeonTex?
I'm working to construct some of this for one subject in my University in Italy, also connected to Arduino.
Thnx

Nino

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as far as i know you have to get in contact with eeonyx - who are based near san francisco - and they should be able to send you samples of their materials or otherwise let you purchase a small amount at a reasonable price.

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pbates123

8 years ago on Introduction

Plusea -

Great demo and I love the display on your computer.  I am interested in how you created the display is this a home made interface or something commercial??

Regards,

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Pluseapbates123

Reply 8 years ago on Introduction

if you check out the last step in this instructable it will lead you to a previous instructable that explains the details in step 8:
>> https://www.instructables.com/id/Fabric_bend_sensor/step8/Software-Visualization/

basically i'm using the free programming environment Processing to write a basic graph application and the code for that application can be downloaded from the link above.

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Pluseajpe1456

Reply 8 years ago on Introduction

Unfortunately they don't offer information on ordering samples or even small quantities, but you should be able to use the contact from on their website, or email to: info@eeonyx.com