Turn Your Entire Phone Into a Touchscreen

Through avid use of my smartphone, I found that while playing some games my hands were positioned awkwardly, making it challenging to reach some of the controls. I figured most of the phone's blank space could be put to use, so I came up with an idea: make a tape that transfers your touch to a different area of the screen. This allows you to:

• Use the screen without your fingers blocking anything
• Create custom off-screen controls for a game
• Touch a part of the screen that is normally unreachable (phone screens are getting pretty big nowadays)
• Anything else you can think of!

Thanks to mikey77 for the inspiration to remix his idea from this Instructable on clear conductive glue!

If you like the idea, please consider voting for me in the phone and remix contests!

Step 1: How Does a Capacitive Touchscreen Work?

Most modern cell phones use a technique called capacitive sensing to figure out where your finger touches the screen. Capacitive touchscreens are made of multiple layers, which can be seen in the pictures above. The actual sensing is done by a grid of wires set up so that each direction of wires is on a different layer. Each of these wires has set capacitance values to them, which is all measured by a very fast processor behind the phone's screen.

When a finger makes contact with the surface of the screen, the capacitance decreases in the wires below the touch (in both the x and y directions) because some of the current is traveling away from the processor and into your body. For this to work, the object touching the phone (your finger) must be conductive and able to absorb some energy that the phone gives out (your body is typically grounded, so electricity can pass through you freely to reach ground).

TL;DR: Touchscreens work because your finger is conductive and absorbs a small amount of electricity from the phone.

How will this project use the touchscreen?

By using what we know about touchscreens, we can hack them! A touch screen relies on a conductive material to come in contact with it, but why not have a wire in between that's also conductive?

In this project, we will route a wire from a point on the touchscreen (the target) to a point outside of the touch screen. This will allow the current from the touchscreen to flow through wire, then to our body, then to ground.

Step 2: Materials

Purpose	Material I Used	Possible Replacements
Secure the wire to screen	Transparent Scotch Tape	Packing tape Lamination Other clear adhesive
Carry current from screen to finger	Strand from a stranded-core wire	Strand of steel wool (rusts) Speaker wire
Create a good contact between the wire and the screen	Elmer's Glue	Gel from ECG electrode (for long-term applications) Clear silicone (not tested) DIY conductive gel (spotty results) Other type of "school glue"
Make the glue conductive	Conductive Thread	Graphite Powder Anything in this Instructable (credit mikey77)

Tools:

• Toothpicks
• Scissors
• Aluminium Foil
• Screen Cleaning Cloth
• Wire stripper
• Pliers
• Hobby Knife

Step 3: Make the Tape

Now let's get down to business!

1. Mix a small amount (less than 1 mL) of glue and chopped conductive thread on a piece of tin foil with a toothpick (credit again to mikey77)
2. (Optional) Cut a very small piece of ECG gel (see pictures)
3. Strip wire and cut the wire to desired size or obtain strand of steel wool
4. Carefully cut a piece of tape around 1-2 cm smaller than the wire
5. Make an incision in the tape around .5cm and 1.5cm away from the edge of one side of the tape (please see pictures)
6. Thread the wire through the incisions in the tape so that the wire is mostly on the sticky side of the tape and so that the edge of the wire is around 1cm from the end of the tape
7. Using a toothpick, dab a bit of glue (and, optionally, the ECG gel) on the tip of the wire

TIP:Handle the tape with a hobby knife and toothpicks to avoid getting oil from your fingers on the tape, and therefore making the tape slightly less transparent.

Step 4: Applying It to Your Screen

1. Wipe the screen with a screen cleaning cloth to get rid of oils and dust that could make the tape more visible on the screen
2. Place the piece of tape so that the dab of glue is over the targeted area of the screen
3. Firmly flatten the tape, especially around the target
4. Use pliers to twist the exposed piece of wire
5. Cut off excess wire

Step 5: Test It Out!

There are so many ways to make this, so experiment with what you have (see the materials step for a list of materials)!

I made a simple Android app to test out the connections by recording and displaying each time the touchscreen is touched (click here for qr code)(made using ai2)

Here's where it gets even more fun. This touchscreen tape isn't just restricted to the front of your phone or tablet! See the pictures of some things I came up with!

Don't forget to post a picture of a setup you came up with in the comments if you decide to make this project!

Step 6: Conclusion/Rethinking the Phone

Remember that this is just a proof of concept. It may not work as well as you'd like (having a piece of tape on your screen can be annoying), but hopefully in the near future, smartphones will have built-in use for empty screen space!

Phone designers can create buttons similar to those on the bottom of some Android phones, but with customizable actions, like pressing a location on the screen. However, this isn't just limited to the front of the screen. From the back or side of the phone, users could easily access certain buttons or features on a phone!

To prevent accidental triggering of the buttons, they could only be used by certain apps or only when the phone is facing a certain way. For example, when the phone is held in landscape mode, the user can only hold it a few different ways, so that way only the proper buttons would be active.

If you liked this Instructable, please consider voting!