Stroke Sensor

Intro: Stroke Sensor

This sensor takes some time to make. Repeatedly threading, stitching and cutting thread. But the result is quite effective and you can vary the design of the sensor in order to detect different kinds of stroke. See illustration for variations in stroke sensor design.

Various techniques could be applied to create this kind of "stroke sensor" such as knitting or crocheting loop stitch or rug knotting techniques. This Instructable shows how to stitch conductive 117/17ply silver plated nylon thread and a more resistive 66 Yarn 22+3ply 110 PET thread into neoprene in order to create a "stroke sensor". The rubberiness of the neoprene creates enough friction so that the threads will not come loose when stroking. Meaning you don't have to knot each individual hair. It is important to use these particular threads as thicker conductive threads tend to curl when repeatedly stroked and thus don't work for the stroke sensing anymore.

The publication DIY Wearable Technology also contains information on this sensor and can be downloaded from:
>> http://plusea.at/downloads/DIYWearableTec.pdf

HOW TO GET WHAT YOU WANT:
Loop stitch technique post >> www.kobakant.at/DIY/
Stroke sensor post >> www.kobakant.at/DIY/

VIDEO

STEP 1: Materials and Tools

MATERIALS
For sensor:
* Conductive thread- Silver Plated Nylon thread, 117/17 2ply
* Resistive thread - 66 Yarn 22+3ply 110 PET
both from LessEMF: lessemf.com/fabric.html
* Stretch conductive fabric
* Fusible interfacing

For circuit:
* 1.5 mm thick neoprene with polyester jersey laminated to either side from SedoChemicals: www.sedochemicals.de
* LilyPad sewable LED
* Sewable coin cell holder
both from Sparkfun: www.sparkfun.com/commerce/product_info.php
* 3V coin cell

TOOLS
- Sewing needle
- Scissors
- Iron

STEP 2: Material Preparations

Cut out a piece of neoprene as large as you want the sensor to be. Cut two strips of stretch conductive fabric with fusible interfacing adhered to one side and fuse them opposite ends of the back side of the neoprene. See photos for reference.

STEP 3: Thread Needle, Stitch, Cut

Thread a sewing needle with the conductive thread and take it double-double, so that two strands of thread are going through the needle hole. This is a way to save time and effort since you'll be able to stitch four threads in one go. Of course you can also stitch a single thread at a time.
Start by stitching through from the front side of the neoprene where the conductive fabric is adhered to the back. Make sure the thread goes all the way through the neoprene and makes contact with the conductive fabric before coming out the front again. Then cut all four threads to roughly equal lengths - depending on sensor design - about 2-3cm.
Repeat this over and over again until both conductive fabric strips have "hairs" connected to them. See photos.
Now thread the resistive thread the same way and repeat the same technique over again but this time fill the surface area in between the two conductive thread/fabric strips. See photos.
When you are finished with this, your sensor is finished, in order to see results continue with step three. or simple use alligator clips, an LED or a multimeter or an analog to digital converter to read sensor values.

STEP 4: Complete Circuit

Your sensor is done, but by connecting an LED and a battery you can see how it works. Connect as follows, sewing with conductive thread:
End of one of the conductive fabric strips -- to -- Negative LED lead
Positive LED lead -- to -- Positive battery holder lead
Negative battery holder lead -- to -- End of the other conductive fabric strip

Now when you stroke the sensor you will see how the LED lights up brighter the greater the surface you stroke and the harder you stroke.

Enjoy!

Comments

[TheHawkeye]

This would be great for an application in a child's toy! I imaging it would be very useful for measuring responses for people with mental illness as well. Simply use this as the fur on a teddy bear and you have a smarter toy.

[Arbitror]

This is a neat idea, but what are some functional uses for it?

[learningmasters]

furby s xD

[DIY-Guy]

Combine this with the electronics for a "knock sensor" and you've got a silent coded entry system.

Electronic input device for stroke victims, no pun intended. Or Cerebreal Palsy victims.

Teddy bears that "know" when they're being loved.

Over-limit sensors for closet doors, drawers, etc.

Couch pillows that heat up when you lean against them (and no knobby little bumps to poke you in the spine!).

So... if you really need more ideas, email me. But otherwise, you're welcome for the free ideas that can only entertain someone who does not build such things. (sigh)
--------------------------------------------------------
Plusea, another hit with this one! Go for it!

[swetambri]

how it can be used with stroke victims?

[DIY-Guy]

Each patient is a little different, but many people have limited control of movement. Some C. P. and stroke patients may not have fine motor control but still can make large movements or medium distance motions. Imagine not being able to control a joystick very well, but still being able to poke/push/shove/ or stroke a general area on a sensor pad. Instead of four tiny directions which require delicate motor control, a user might still be able to swat at a much larger target.

It's the difference between a thumb-stick in a laptop compter versus a "dance pad" sensor as big as your chest... maybe even worn as a vest on the chest.

Naturally each patient might need to have their own macros recorded for their specific abilities. There's a new job description waiting for the nurse or therapist with Arduino programming skills, "Patient mobility interface programmer" and "Active-prothesis interface customizer."

Swetambri, did that help at all?      :)

[swetambri]

grt , thnks

[OverSaltedFry]

You could make it into a rug i guess

[corey_caffeine]

make it say ouch when stepped on?

[strangebike]

I work in a preschool and to be honest it could be great for kids to roll walk on or generally do kiddy things on with some kind of attachment to a sound or light generator could be a great fun learning experience for the kids. would start some conversations. Great idea over salted fry

[oddmidge]

Put it in the right places so you can make someone 'light up'. Or for creepy people on the train...

[DIY-Guy]

Creepy people on the train? How about a "Don't touch me or my shirt will taze you bro!" (self defense system to prevent unwanted touching).

... now if we can just get those conductive threads to do double duty with a high voltage source... without frying part of itself, or the legitimate owner.

[Arbitror]

That's not creepy...

[oddmidge]

You have a better use?

[silverbyte]

the idea is awsome, rather than turning LED on, you can make a circut turn on and off when you pet it... like a cat purring... or whatever, this has tons of use...

[spike shadows (secret agent man)]

 Same thing I was thinking

[silverbyte]

read my post on oddmidge / same response to you.
simple idea, can be applied in 1000 different ways... use your imagination

[chaosrob]

A robotic, interactive 'pet'.  Make it purrrr, get annoyed if stroked in wrong direction, a dogs leg that goes crazy when a specific spot is scratched, etc.
Very cool idea.

[Lasrin]

This is brilliant!! 

The uses spring to mind! 
A robot with arrays of these would be able to detect contact.
A amputee could feel the wind (with a neural interface) over their prosthesis. 
A carpet of these would allow for a security system to detect an intruder, without
             a detectable (visible) motion detector.

Can you detect the direction or size of the object (your hand) moving across the sensor?

[davison112]

WEll, for the carpet security thing, Have it set up in a grid pattern, so like, the foot would be Grid space (1,1;1,2)