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Picture of Touch Activated Finger Led (Glove Optional)
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This instructable will show you how to make LEDs light up at your finger tips upon contact with a flat surface. You may choose to sew the components onto a glove to make an LED glove.


Application:
The main reason for this project is to interface it with a multitouch table setup without going through the hassle of setting up an Infrared light pane. (See NUI group for more information.) Essentially, to get a finger recognition software to detect the LED lights as fingertip inputs.

OR

you can just build it for fun :)
 
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Step 1: Materials & Tools

Materials:
* 3v coin battery (I use model C2032)
* LEDs (Choose depending on application or personal preference)
* Resistors
* Acrylic
* Scrap plastic sheet (can be from packaging)
* Scrap aluminum sheets (can be from a softdrink can)
* A pair of earphones (preferably one you wouldn't miss)
* Conductive tape
* Wrist strap

Tools:
* Soldering kit
* Rotary kit
* Digital Multimeter (Optional)
* Sand paper/bits
* Lighter
* Scissors
* Hot glue/glue
* Clear Tape

Step 2: Design the LED Circuit Layout

Picture of Design the LED Circuit Layout
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Step Overview
a. Decide how many and what kind of LEDs you want to use. I used three 3mm orange LEDs
b. Calculate how much resistance you need with a 3V power (from the coin battery). I used this online LED calculator.
c. Determine the length of your wires. Measure out how long of a wire you would need for each of your fingers. Allow for extra room for bending and wire cutting mistakes.

Tip
a. To make it easier to work with two hands you can use a transparent vinyl glove as an aid. Just slip on the glove and draw out where everything should go on the glove. Now you can use the glove to measure out the length of the wires.

b. For my application, I need LEDs with light in the range of infrared or close to infrared. I tested with my modified camera (that has a 850nm bandpass filter) and confirmed that it can see LEDs of colors red, orange, and yellow in addition to 850nm IR.

c. You can use alternative wires instead of earphone wires but I find earphone wires to be compact (each wire already has 2 strands) and flexible. Alternatively, you can use conductive threads and sew them onto a glove.

Step 3: Strip and Join Earphone Wires

Picture of Strip and Join Earphone Wires
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Cut the earphone wires to length (from step 2) and strip the earphone wires at both ends. You will notice there are two threaded wires in side each earphone wires. (Do not use the jack wire as it has three wires inside) We are going to use one of the wires for the positive current and one for the negative current. You would need to remove the non-conductive coating from each of these threaded wires so they can be joined later.

In my case, I am only planning on building a three-fingers setup so I cut three pieces of wires (one for each fingers). One one end of the wires I joined the three positive strands together and the three negative strands together to create two main strands. (You can arbitrarily determine which color is the positive strand and just stick with it.) The other end of the earphone wires I just left it with two strands coming out each end to be connected to the finger piece later.

Step Overview
a. Cut and strip wires
b. Burn wire ends to remove fibers inside the wires.
c. Sand away the non-conductive coatings at the wire tips.
d. Twist and connect the positive wires together at one end; do the same for the negative wires. Leave the wire ends going to the fingers loose.

Tip
You can test to see if the wires have shorted or is working properly by using a multimeter on a continuity setting. Touch the ends of the probes to the ends of the wires. The multimeter will emit a beep when there's current flowing through from end to end.

Step 4: Build Coin Battery Holder

Picture of Build Coin Battery Holder
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In this step we can build a easily removable coin battery holder that sits at your wrist.

Step Overview
a. Using a piece of aluminum sheet with non-conductive coating, bend it to encase a coin battery. Leave one side open for the case cover.
b. Make a battery case cover from a piece of scrap plastic and adhere two pieces of conductive tape. make sure one of the conductive tape will touch the positive terminal and the other will touch the negative terminal of the battery. We will be soldering the earphone wires to these conductive tapes.
c. Connect the case to a wrist strap. (I used old watch strap and a bit of fishing line to hold it in place.)

Tip
To make an aluminum sheet non-conductive just sandwich it between transparent packing tape. To make conductive tape, you can use strips of aluminum foils strengthened with tape. (but I heard they are hard to solder to)

Step 5: Build the LED Casing/Finger End Piece

There are several ways to make this. I personally went through several iterations to get the design I have now but the concept is the same: Connect one of the LED legs to one of the earphone strands and leave the other open. When getting the LED to light up, the finger will push the unconnected wire strand in contact with the open LED leg, thus completing the circuit.

In my case, I used a piece of aluminum strip coiled around my fingertip to act as both a conductor of the negative current and structural support. I will touch the cathode leg (-) of the LED. For the positive current I used conductive tape and a resistor to connect the anode leg (+) to the earphone positive strand.

Step Overview:
a. Cut acrylic to finger size.
b. Drill a hole in acrylic to house the LEDs
c. File down LED if it is too tall for the acrylic thickness.
d. Tape two pieces of conductive tape to one side of the acrylic. (these will be the positive and negative contacts)
e. Put LED in the acrylic and bend the legs. Each touching a piece of the conductive tapes.
f. Solder the LED legs onto the conductive tapes.
g. Solder a resistor to one of the conductive tapes.
h. Trim off excess LED legs
i. Hot glue aluminum coil to the acrylic

Caution
Make sure to the keep the positive side and the negative side separate on the finger piece. Use clear tape on the aluminum strip if you have to.

Step 6: Solder Everything Together and Test

Picture of Solder Everything Together and Test
Step Overview
a. Use solder or conductive tape to connect the finger piece to the earphone wire strands.
b. Solder the wire strands to the coin battery casing cover (the piece with conductive tapes)
c. Slip on the finger end piece and use your finger tips to push the aluminum strip together with the exposed LED terminal. The LED should light up.

Tip
To avoid the wires going all over the place you can cut some coils and make finger rings out of them and slip the wires under the ring.

Using it with Multitouch Setup
Start up Core Community Vision or Reactivision and adjust the camera sensitivity till you can see each lighted LED as a finger input. You may wish to cover the acrylic finger piece with something softer so it doesn't scratch your surface.
Can someone please explain the process of assembling?
drone1822 years ago
is there a way to set this up with a stronger battery?
fgil3 years ago
Great idea. Is just what I was looking for!!!

I'll try to use smaller battery in each finger to make it wireless and then try to make some IR led touch sensitive switch to be used with de Wee remote touch screen.

Do you think it can work??
jsanchez293 years ago
that is pretty cool and simple I can't wait to try it
obedfarley3 years ago
It's like Mickael Jackson
Where it says Materials & Tools what do you mean by LED's?
And, where do you buy them?
http://lmgtfy.com/?q=What+are+%22LEDs%22%3F

You're welcome =)
AH, thank you so much!
:DDDDDD
Lol no problem!
d4haris3 years ago
this site very best for stuff
awoodcarver3 years ago
Very nice job ...The tip with the glove so simple but it makes it much easier to do the build
Am I the only one that saw this and thought of Minority Report?
Doddity3 years ago
The diagram looks kinda like veins. Great instructable by the way
Adum243 years ago
I just had...THE greatest idea ever. You should interface it with the arduino so when you touch a specific finger, it plays a note as a beep! THAT WOULD BE THE SICKEST THING EVER!!!
jeshsieh (author) 3 years ago
I love the simplicity of Johnny Lee's multitouch using Wii but I haven't done too much research into it. Please let me know if anyone has a Wii setup running Flash programs. Or how it turns out if you use the 'glove' method and Wii together. Note: I've seen IR for the Wii method to be 940nm instead of 850nm. This could be good since you can get that from a remote control. Also my 850nm IR LEDs were a bit bright for my camera.
batman963 years ago
OOOh,
This reminded me of the glove the Goa'uld where in SG-1.
jeshsieh (author)  batman963 years ago
I googled 'Goa'uld' (I am more of a BSG fan :]) to be "a parasitic alien race that use other beings as hosts". Thanks for mentioning it because their technologies are pretty awesome. See here and here. I assume the glove you are talking about is called "Kara kesh."
Blaaken3 years ago
This mixed with this: http://johnnylee.net/projects/wii/

Would be amazing.
Great project!

I'm going to use just one, but put an IR LED on the "Up" side of the finger, then I can use this as an IR pen with my Wii Interactive Whiteboard system.
mikeasaurus3 years ago
I like this idea!