Stickytape Sensors

Simple Pressure and Bend Sensors made from stickytape, Velostat, conductive thread and small pieces of conductive fabric.

Basically you just have to get the conductive surface and Velostat ratio right. I find the following methods work best. As little conductive thread as necessary to cover the sensitive surface. For up to a two cm wide strip, it can be enough to have a single thread running down the center of the strip and three layers of Velostat in between each thread.

VIDEO
Stick a stickytape bend sensor to your wrist with some extra stickytape!

VIDEO
Make your stickytape bend sensor and hook it up to your computer in less than 4 minutes!

VIDEO
This video shows the full process of making a stickytape bend sensor and hooking it up to your computer in less than 5 minutes.

VIDEO
This video shows the graph of a super slim stickytape bend sensor inside a regular drinking straw.

Step 1: Materials and Tools

The materials used for the sensor are easy to buy online. They are also relatively cheap. I would guess that you could make up to 1,000 sensors for less than 30$
When shipping to north America, I like to order from LessEMF because they stock all three essential items, are quick to ship and the prices are reasonable.

Velostat is the brand name for an anti-static plastic manufactured by 3M. The plastic bags in which sensitive electronic components are packaged are made of this material. It also runs under the names: anti-static, ex-static, carbon based plastic, ESD, Linqstat (made in china), Lagerbeutel (German for storage bags)&
So you can also cut up one of those black plastic component bags if you have one at hand. But caution! Not all of them work!

MATERIALS:
- Any kind of stickytape will work, but it can be nice to use a duct (gaffer) tape for its flexibility and robustness. You will find a wide selection of tapes at your local hardware, office supply store and stationary stores.
- Velostat by 3M from http://www.lessemf.com/plastic.html
- Conductive thread from http://www.lessemf.com/fabric.html
- Conductive fabric from http://www.lessemf.com/fabric.html

TOOLS:
- Knife
- Scissors
- Random objects to handle stickytape

Comments

[bobank]

What is stickytape. I am not from this country and maybe i used it but not under that name. Can that be any tape or some specific and where to buy it.
Thanks

[Plusea]

you can use any kind of tape that is sticky. scotch tape, gaffa tape....

[fburali-forti]

Hey, great instructable! I'm planning to build sensors for an interactive staircase and this looks perfect. What was the actual peripheral you used to connect to your laptop? Was that an arduino or just some other serial to usb? Thanks for all the help and congratulations again!

[Plusea]

yes. an arduino and you can use the internal pull-up resistors as voltage dividers for the sensors!

[WillTheRescue]

 Could I ask what software you were using on the computer?

[Plusea]

I'm running an application written in processing (www.processing.org) - you can find out more about it in step 7 of this instructable:
>> http://www.instructables.com/id/Fabric_bend_sensor/
hope this helps.

[InDaClub]

Hi all,
i just want to know the difference of preassure sensitivity of ESD chip foams like
http://www.esdproduct.com/detail.php?pid=13857&cid=

Actually i want to build a electronic music keyboard which is completely preassure sensitive. I know that it will need a procedure to calibrate the values from sensor to send a precise value to computer. I dont know the actual difference between low density foam and high density foams or velostat. I just want to know which one will give me huge variation of resistance against preassure of the three matrials?

My guss is that high density foam will not give good results as it will be variying its resistance in a narrow band.

[Plusea]

I have not got much experience with the foams, but Velostat has a nice (large) range from 2K - 200 Ohm.

[InDaClub]

Plusea thanks for a quick reply. hearing good experience of yours i just want to know if velostat is returns to 2K value consistently. I am planning to etch a copper clad and make PCB with contacts (like those in LDR etc). then i will plate it with some anti corrision like may be gold plate it, then put a velostat strip over it with metal pieces (completely flat) or should i use steel slightly bent underneth each key so that they act as small spring's(?).

actually i think that velostat wraps arround wire and that is what make it a force sensing resistor, when you release it, it makes less contact and the surface area of contact decreases. I want to be sure to get the maximum variation like my piano has a after touch sensor which is a preassure senesor strip giving values from mega ohms down to 300 ohms and i know its very very expensive to install under each 61 keys. currenly it works for the entire keyboard and give one resistance value for all keys. btw i can design using microcontrollers intelegent circuitry.

[Plusea]

I'm not sure you can rely on the consistency of the Velostat. It may well change over time under use. Another material to look into would be anti-static rubbers like Zoflex. I would recommend experimenting with the Velostat since it is cheap and easy to use.

[InDaClub]

ZL45.1 is exectly what i need. Thanks.

You know a lot about these things. And very nice article here.

[katsideswide]

Hi!

Thanks for a good instructable!

I'm a little lost however. I made the sensor as instructed, using the blue "labestat" dissipative film that my arduino came in. I then installed the arduino and processing programs, plugged in my arduino and installed the program on it.

Then I connected one side of the pressure sensor to the analog in 0 pin, and the other to the analog in 1 pin and ran the processor program. It gave me the graph but all 6 inputs were fluctuating up and down like crazy! applying pressure makes no discernible difference, apart from maybe making it fluctuate more. Disconnecting the sensor makes all the bars calm down a little but not completely.

Does this sound like a problem with the sensor or a problem with the arduino to you? I'm a real noob at this! I'm trying to make a small toy that makes a sound when the user picks it up. Capacitance would be best I think but it sounds super tricky...

Anyway. Thanks for a cool instructable!

[Plusea]

first of all, i'm not sure if the libestat has similar piezoresistive properties to velostat and linqstat and thus might not work to construct the stickytape pressure sensor. to test this separately from the arduino, connect the two sides of the sensor to a multimeter set to measure resistance and see what happens. if you get changes in numbers that look reasonable, then it should also work with your arduino setup.
one mistake i see is that you want to connect one side of the sensor to ground and the other to analog input 0. that is what the code is written for.
another test to do is to simply connect two wires, one to ground and one to analog input 0 and see what happens in the graph. when they are not touching the graph should be still. when you touch the wires together, one or more of the graph bars should swing all the way to the other side and remain stable there.
i hope this helps you. let me know if you have more questions.

[katsideswide]

Hi Plusea,

Thanks very much for your help! I've managed to get a better result now that i've connected the right things together (noob fail...)

The program responds as described when i connect the ground and input 1 together, so i guess it must be my switch. I'll try again with a different anti static! :D

Thanks so much!

[caplinq]

CAPLINQ offers a Velostat alternative called LINQSTAT and we stock it in both Canada and the Netherlands.  You can see the link here:
http://www.caplinq.com/linqstat-vcf-s-series-linqstat-volume-conductive-film.html

We will soon be offering standard sizes in 2mil, 4mil and 8mil.  Check the site for updates.

Due to popular demand, within a month, we are also going to offer a silver conductive Velcro (Hook & Loop) as well and anti-static fabric.

Contact us for status.

[VALKIR]

 hey, I really enjoyed looking through your sensor instructables and also the youtube vids (oh and i really liked the "sencitive glove" ) but I dont know if i can find the materials you used. i read above that you can use wire instead of the thread (which reduces bendy-ness) but the other things i'm missing are the conductive fabric - you used some copper mesh ... can aluminum foil be used as well? like thicker, i have some of that ,not the thin food packing one? and also- the Velostat , what common household material can I use instead? it needs to be non-conductive,right? will a strip of electrical tape work ? or is that velostat semi-conductive under certain conditions (like bending)?

[VALKIR]

 oh, now that I've done some reading about the velostat  - isnt it used for shielding electronics and stuff? if so- cant I just use the "static" bag from my motherboard? i'm starting to feel like can't be closer to the truth without missing the point completely ... lol

[Plusea]

yes you can totally use wire and aluminium foil (the regular kitchen stuff will work fine) or even copper tape. and the velostat is anti-static packaging material but only the black anti-static bags work, and then not all of them. do you just have to check. this is also a great non-fabric instruction:
http://www.imagesco.com/articles/flex/sensor-pg1.html

[VALKIR]

nice, thanks ;) and about an hour or so ago i finished playing with the thing I made ... with variable success :D (couldn't resist the pun lol ). 

[Plusea]

would you post some pictures or an instructable!
it would be great to see what you made:-)

[bsoares]

Very good!
Congrats

[SNYG]

Can I get this pressure sensor calibrated

[Skyver]

Awesome. You just saved my project with this! I was looking for pressure sensors but they are not available in this country. Your contribution just made it possible. I'll be sure to give you some credit.

[jx4]

Is there a reason for using conductive thread rather than just ordinary electric wire? Can one use wire instead of conductive thread for this experiment?

[Plusea]

regular wire will work, but won't be as soft as the thread.
also see these great instructions:
>> http://www.imagesco.com/articles/flex/sensor-pg1.html
>> http://www.pulsar.org/archive/int/timswork/Velostat.html

[jx4]

Thank you very much :-)

[endolith]

So it's actually a pressure sensor? And bending it causes there to be a point of higher pressure?

[Plusea]

Exactly!

[sharlston]

tried and it works ps i put these in my bedroom and when someone steps on it it sounds a silent alarm to my computer

[Plusea]

cool! i'd love to see some photos! do you use the pressure data for anything? differentiating between how much pressure is exerted - weather it is a mouse or human? but that also brings up the point that they can be used as very flat switches.

[sharlston]

i would take some pics but im only 13 and i dont really have a camera and i dont do anything scientific

[Lftndbt]

I would just like to comment and say, that I read all your efforts with great excitement.
You inspired me to make my avatar RoBot shirt. http://www.instructables.com/id/RoBot_Gets_E_textiled_First_Ever_Interactive_Bot_/
I really hope you try and combine many of these sensors and switch's into one EPIC jacket of coolness, or something of similar nature.
I would like to see them all combined through a single or several circuits on the one garment. Even if the circuit is just to utilize the individual items and nothing more. I think that would show case your overall talents in the one item.

Just my thoughts. Keep them coming!! :-)

[Plusea]

nice robot! i like the crocodile clips coming out of the pocket to power it! it think this gives it a really nice look!

[cameron20020]

nice idea, and rather simple, yet it looks like it could be reliable

[Plusea]

yeah, i'm amazed too, they are really super reliable so far. i started sandwiching them in some Shapelock and this makes them even more stable >>
http://www.flickr.com/photos/plusea/3474231732/in/set-72157617163832637/
video coming soon...

[fearsom 1]

ya i noticed something though in the first video, it has only a 1-demension sense, meaning if he bends his arm up all the way, it still goes left

[Plusea]

you're right. the sensor does not differentiate between bend in one direction or another. also, if you touch it and press, it will react in the same way, since basically it is a pressure sensor measuring bend because of it's placement.

[Taotaoba]

Cool! Gonna to see your other inst'ls too.