Introduction: Create an Interactive Living Wall

This instructable was made as part of the final project requirement in the CS graduate course "Tangible Interactive Computing" at the University of Maryland, College Park taught by Professor Jon Froehlich. The course focused on exploring the materiality of interactive computing and, in the words of Hiroshii Ishii, sought to "seamlessly couple the dual worlds of bits and atoms." Please see our course wiki for more details.

Inspired by MIT Media Lab's "Living Wall", we created this interactive wall to imitate a living circuit at the University of Maryland Human-Computer Interaction Lab Hackerspace. Functionalities include lit up grapes, capacitive touch sensors to toggle lights on selected grapes, homemade butterfly speakers, and removable LED butterflies which we like to call butterflights!

Please keep in mind that this is a work in progress! We've been able to work out some parts of the wall so far, however this in an ongoing project that will hopefully be done sometime in the beginning of February. We wanted to offer the instructable community of how to do what we've done so far! :) I'll be providing updates on how to do each part once a section is finished. If you have any questions, please leave them in the comments section below. We'll do our best to help out! Happy hacking. :)

A bit about the "why":

A project like this takes quite a bit of planning and customizing depending on the amount of space you have on your wall/canvas. You may find yourself changing certain steps, like the circuit diagram, to adapt it to your wall. The main idea behind this project is to merge the hardware and circuitry we often work with in the hackerspace with the outside world. Our hackerspace has windows, but these windows don't lead to the outdoors. So we decided to bring the outdoors...well, indoors!

Since the circuits looked somewhat like vines, we thought it would be neat to make grape vines out of the circuits, and simultaneously make them interactive. Fun!

You'll find that many parts of this projects were taken from open-source code, instructables, and tutorials from other people. We'll link you to all of these sites as we move along this instructable.

Let's get started!

What you'll need:

Art supplies (all can be found at Michael's or any other art store)
- Various colors of acrylic paint (you can customize this, but we used different shades of green and red)
- Small, round paintbrushes
- Modeling paste
- Artificial grapes
- Artificial grape vines with leaves
- Artificial butterflies (we used both small and large sized butterflies)

- ATtiny85 (1 for each capacitive sensor created)
- LM386 audio amplifier (1 for each speaker created)
- Arduino Uno
- Mosfet Transistor (x3)
- Voltage Regulator (x2)
- Heatsink (x3)
- Clear, white LEDs (we used about 155 of them)
- Various resistors (will discuss how much is needed)
- Various capacitors (will discuss how much is needed)
- Copper Tape (make sure both sides are copper; some have silver on one side)
- Copper wire
- Neodymium magnets, tiny(about 1cm across) and large(about 3/4inch across)
- 15v AC/DC power adapter (you'll need to strip these wires, so use one that you don't need for anything else)
- Audio cable (you can use an old pair of headphones)

- Soldering iron
- Solder
- Wire Cutters
- Wire strippers
- Some AA batteries for testing
- Painter's tape (we didn't use this, but it would be very helpful to have some)
- Hot glue gun
- Hot glue
- Pencil (one that can easily be erased)
- A good eraser (we don't want smudges)
- Scissors
- Paper
- Tape

Step 1: Draw and Paint the Circuit/vines and Grapes

Before starting anything, you'll want to map out where you want everything to go on the wall. We started by drawing a circuit on the wall with a pencil. Make sure you don't press down too hard with the pencil when drawing down your design as you'll want to easily be able to erase these marks. Most of you may not have the paint you originally used to paint the wall over the marks you make, so press lightly! This design may slightly change as you start to work on the wall, especially where "wires" will be drawn. But that's ok!

We drew everything from the circuit to where the grapes would be. Keep in mind that our circuit looks like a real circuit, but essentially we're treating it like vines that grapes grow on. This mixture of themes seemed to work well for a hackerspace. 

Drawing the design:
Start with drawing the circuit/vine diagram. Basically you'll want to create a variation of perpendicular lines (90 degree angles). Make sure they are random so they give the affect of looking like a real circuit.

Next you'll want to draw out the grapes. Draw circles as close to one another as possible in sort of a triangle shape where there are more grapes at the top, attached to the vine, than there are at the bottom. Again, you'll want these grapes to be of varying sizes. The size of the individual grapes can be the same. Add more grapes to a bunch to make them look bigger.

Once you've drawn everything out with pencil, you're ready to start painting the circuit/vines onto the wall.

Finding the right color green:
We mixed a darker, grassy green with some light green. You can mix and match to see what color green you prefer. Keep in mind that the color you create will show up darker on the wall when it is dry. Try testing out the paint on a piece of paper first before painting on the wall to see how the color will look when it is dry. Depending on the concentration of the acrylic paint you buy, you may want to add some water to your paint to ensure that you don't use up all your paint quickly. This will be ok since acrylic is water based. Generally, the less expensive acrylic paint that you can buy at Michael's will only need about a teaspoon of water mixed in for every 2-3 teaspoons of paint.

Painting the vines:
We recommend using painter's tape to create straight lines on your wall. Place some tape above and below the line you'd like to paint. This way, your lines will turn out nice and clean. We didn't use tape as we didn't have any at the time. But here's how we did it...

Once you've created the right color green, take your round tipped paintbrush and begin to paint over the circuit design you drew with your pencil. These circuit lines can be of varying sizes. We generally made the lines thin. If some lines were crooked, we painted over them and consequently made them slightly thicker. This is ok since not all vines are the same size, thus making the circuit/vines look more realistic.

Finding the right color purple:
For the grape colors, you'll want to mix several colors together:

- 1 teaspoon of Crimson red
- 1/2 teaspoon of a normal red color
- 1/8 teaspoon of blue
- 1/8 teaspoon of yellow

Mix in about 1/2 teaspoon of water to ensure that your paint isn't too concentrated. Again, remember the color you create will show up slightly darker on the wall. Try testing out the paint on a piece of paper first before painting on the wall to see how the color will look when it is dry.

Painting the grapes:
Start to paint in the circles you created for the grapes on your wall. It's ok if you have white spaces in between each grape since this will be covered over later. The edges are what are important. Make these edges look as round as possible.

Step 2: Strip an Adapter for Power

We used a 15V AC/DC adapter to give power to our wall. This adapter was actually slightly old, so for some reason it ended up giving us 19V instead of 15V. We were surprised to find that this part's actually quite simple.

Step 1
Grab an old adapter that you may not need anymore. Again we used a 15V adapter that ended up giving us 19V. You can test this by using a multimeter. Generally, the positive end will be on the inside of the adapter tip and the negative will be on the round, outside section of the tip. The following video shows how to properly test your adapter. Make sure your adapter is plugged into the wall before you test it! Otherwise, you will get a reading of 0.

Make sure you take note of about how much power your adapter is giving off. This will be important for later when we create the LED grapes so we can know how much resistance we need.

Step 2
Cut off the tip of the adapter as close to the end as possible. The tip is the section furthest away from the adapter itself. It is the part where we test the voltage levels with the multimeter.

Step 3
Strip the wires. Generally the wire with the white stripe on it will be the positive wire and the other wil be the negative. We can test this again with the multimeter. Connect the red wire on the multimeter to the wire with the white stripe and the black wire on the multimeter to the other wire. Set the multimeter to measure DC power. Make sure your adapter is plugged into the wall! Be careful when testing the exposed wires so you don't shock yourself (as we did to ourselves many times).

If the reading on the multimeter is a negative number, this means that the wire with the white stripe is actually positive and the other is negative. Make a note of this for later. You can easily label the positive wire with a piece of red tape.

Step 4
Find a convenient place to plug the adapter into the wall that will allow the wire to reach the circuit on the wall. We found that one of the plugs under one of the windows was the best place to put ours. The image above shows the two wires connected to the wall through strips of copper tape. For now, use some tape to hold up the two wires on the wall where you'll want to permanently hold it down later. If your adapter is still plugged in, make sure the two wires do NOT touch. It won't be pretty.

Step 3: Create the LED Grapes

Next, we'll want to create the LED grapes. Basically, we'll be inserting an LED into each individual grape. We used something around 135-155 LEDs for this as each grape bunch required 5 LED grapes.

Step 1
Pick lots of grapes! Grab the grape bunches that you bought from the art store. These grapes are usually attached onto the stems through a T-shaped piece of plastic that is inserted into each individual grape. Pick as many grapes as you'll be using for the LEDs. You'll actually need to pick more for later, so you may as well pick them now while you're at it! You'll roughly need twice as many individual grapes as you have LEDs. So if you have ~135 LEDs, you'll want to pick about twice as many as that, so about 270 individual grapes.

Step 2
Before we insert the LEDs into the grapes, we'll want to test them to see if they work. Sometimes the LEDs that are sent in bunches are damaged, so it's good to know they work before putting in the effort to insert them into the grapes. Grab two AA batteries. Attach the positive end of one battery to the negative end of the other, as shown in the image above. This will increase the voltage amount to 3V, which will be enough to power the LED.

Then attach an alligator clip to the longer pin on the LED, which is the positive pin. Touch the other end of the aligator clip to the positive side of the batteries. Touch the other pin (the one without the aligator clip) on the LED to the negative side of the batteries. If the LED lights up, you're good!

Step 3
Now, we want to put the LEDs into the grapes. You can see that each grape is hollow and has a hole in it. Insert a pair of pliers into the grape and stretch it open. Be careful not to stretch too much, otherwise you will tear the grape. Take an LED and insert it into the grape. Be careful not to scrape the LED against the pliers. Pull out the pliers. As you pull them out, the grape should wrap itself around the LED.

This is a tedious task as it must be repeated for every single LED, but it'll be worth it in the end!

Step 4: Create the Grape PCB & Glue Onto Wall

We found that using a perfboard was the easiest method in putting the grapes on the wall. Each individual painted grape will need it's own custom-shaped perfbaord. We'll be cutting out custom-made pieces of perfboard for each painted grape bunch.

Step 1
Take a piece of perfboard and put it up against the wall on one of the painted grape bunches. You should be able to see through the holes on the perfboard to see where the edges of the painted grapes are. Using a pencil, roughly outline the shape of the grape bunch. It's best to measure it somewhat smaller than the actual size of the grape bunch since this way it will be easier to cover it with modeling paste later.

Step 2
Cut out the perfboard along the lines you drew.

Step 3
Using the circuit diagram in the images above, place the LEDs on the perfboard anywhere you like. Connect the positive pin on the first LED to one end of the resistor by twisting them together. Then, connect the negative pin on the LED to the positive pin on the next LED by twisting them together. Continue this until all the LEDs are connected to each other in series.

Step 4
Before you solder anything together, test what you have created with the power coming from the wall adapter. If everything works out, move on to soldering the connections together.

Step 5: Cover Grapes With Modeling Paste

We used Liquitex flexible modeling paste and spare brushes to apply to the grapes.  

Step 1
Begin by taking a dash of the paste on your brush and apply generously to an open section of the perfboard or the background grape bunch image you painted earlier. Be careful not to get too much of the paste on the grapes as it is mostly opaque and will hide more of the light coming through the grapes. Keep applying paste so there is a thick layer covering the perfboard and the circular painted grapes.

Step 2
Move your brush around in the paste in a circular movement to move the paste around . Try to mimic the circular paint you had on the wall previously. Create a small, spherical mound on the inside of each grape circle and around each grape. Using the painted grape circles on the wall as a template, create a  circular mound large enough to hold a grape without an LED.

Step 3
Once you cover the entire grape bunch and perfboard with the paste, place extra grapes in the spaces where you created paste mounds that are lacking individual fruits. This will make the grape bunches look more full.

You won't be able to paint over the paint just yet. You'll have to allow at least 24 hours for the paste to dry. Either way, we'll need to wait until after all the wiring is done before we can start painting over these.

Step 6: Create the Capacitive Touch Sensor

We used an ATtiny85 and an Arduino UNO as an ISP to program a capacitive sensor. We used the tutorial on programming the ATtiny85 with Arduino 1.0.1 from the high-low tech group at the MIT Media lab.

The sensor code we will programming onto the ATtiny came from this tutorial. You can download our customized code from github.

First we used a 5V voltage regulator from Radioshack to drop the 19V from the adapter down to 5V for the ATtiny. The micro controller can only handle max 5.5V so we need to drop it down to avoid blowing the micro controller. We needed a heat sink to prevent overheating as the voltage regulators burn up the excess current as heat. Radioshack also has those.

First, we need to set up the Arduino UNO as an ISP to program the ATtiny85. Follow the tutorial provided in the first link to do this.

Next, upload the code provided on our github page to the ATtiny. Once the ATtiny is programmed with the touch code, we connect the output to a MOSFET transistor to switch on the LEDs which are running off of 19V power. 

This should complete the circuit and turn on and off the LED grapes when the sensor is triggered.

Step 7: Create the Butterfly Speakers

To keep the overall theme of the wall in place, we made speakers out of some butterflies we bought. We followed this tutorial in order to make the butterflies. The only difference in our design is that instead of gluing the paper cylinder to a paper plate, we glued it to a butterfly. The affect was almost exactly the same.

Similarly, instead of gluing the magnets and springs to a bucket, we glued these straight onto the wall. These can be seen in the images above. The step by step images are almost identical to what was done in the video tutorial below.

Step 8: Strip Audio Cable and Test Speakers

Step 1
Grab an old pair of headphones that you don't want to use anymore. Cut off the wires as close to the earbuds as possible.

Step 2
Strip both of the wires. You will see two copper wires, a red wire, and a green wire.

Step 3
Twist the green and red wire together. Twist the two copper wires together.

Step 4
Wrap a piece of copper tape around the twisted copper wires. Then wrap a piece of copper tape around the twisted red and green wires.

Step 5
Place the magnets on a flat surface. Position the paper cylinder on the butterflies on top of the magnets so that the magnets are inside the cylinder. Temporarily tape down the ends of the springs (the ends that are away from the butterfly) on either side of the magnets.

Step 6
You can now test the speakers. Take an alligator clip and clip it on to one of the pieces of copper tape wrapped around the twisted copper wires. Clip the other end of the aligator clip onto either one of the wires of the speaker (doesn't matter which one).

Now take another aligator clip, clip it onto the other piece of copper tape wrapped around the twisted red and green wires, and clip the other end of the aligator clip to the second wire on the speaker. It doesn't really matter which aligator clipped is clipped onto the speaker wires. 

Step 7
Plug the audio cable into something that can play music (phone, laptop, etc). Play a song and listen to the speaker. It won't be too loud, but you should be able to hear it well enough. 

Step 9: Glue Speakers to Wall

Glue the large magnets with hot glue on the wall where you would like the speakers to be placed. Press down hard until it dries.

Next, take the butterfly speakers and put the paper cylinder section on top of the magnets so that the magnets are inside of the cylinder. Position the ends of the springs (the side away from the butterfly) on the wall and mark a small "x" to indicate where you want to permanently glue them.

Put a dab of hot glue on both ends of the springs (away from the butterfly) and glue them onto the wall where you made the "x" marks. Press down hard until they dry.

Now test the speakers once again, as explained in the previous step, to see if they still work properly. We don't want any mistakes in the future.

Step 10: Create Amplifier for Speakers

We used the LM386 speaker amplifiers to amplify our butterfly speakers. We followed this instructable to create it 4 audio amplifiers since we ended up using 4 speakers. These amps are hooked up in parallel. The last image also shows a schematic of how an individual amp can be set up.

Generally the amps can take something between 5-15v of power to boost the sound on the speakers. Since we were using 19v from the wall, we needed to use a voltage regulator to drop the power down to 15v. Once again, we used a heat sink to ensure nothing burns up. Gate and Source pins each have a .2uF capacitor with the pin closest to the white strip on the capacitor connected to ground and the longer pin connected to gate and source.

The left, gate pin is also connected to power coming from the wall adapter. The center, drain pin on the voltage regulator is connected to ground coming from the wall adapter. The right, source pin is essentially the 15v of power that will be given to the amplifier chips.

Step 11: Screw Capacitive Touch Sensor PCB to Wall

This step can be modified to fit your circumstances. We had pre-cut holes in our perfboard that we connected the components to, so we screwed the board onto the wall. You can also attach magnets to make the board removable, as well as velcro and other things.

Step 12: Connect All Grape Bunches to VCC/power

Each positive lead from the grape series bunches should be connected in parallel to the adapter positive lead on the wall.

Step 13: Connect Selected Grape Bunches to Output Lines of Capacitive Sensors

In this specific project, we created two capacitive touch sensors. You can pick which lights you want to light up by touching each capacitive touch sensor. 

Important Tips
When connecting leads using the copper tape, be sure to use electrical tape to prevent layers of copper tape from touching one another. If you need to go over a piece of copper tape on the wall with another piece of copper tape, make sure you cover the copper tape on the wall with electrical tape first.

Additionally, when connecting pieces of copper tape together, make sure the copper tape overlaps well in the corners you need them to overlap, otherwise you will break the connection. It is important for you to use double sided copper tape for this to work. There are some types of copper tape where the adhesive side is made of silver and not copper. Therefore, when you overlap the pieces of copper tape, they will not connect.

Connecting Grapes

As stated in a previous step, the negative leads from each grape bunch should be connected to the drain lead from the 3-pin MOSFET transistor of a single touch sensor. The negative leads should all be connected in parallel to the same drain lead.

The image above is the best example we have of this explanation. Basically you have one of two options:

1) Connect the negative lead on a grape bunch to the negative wire coming from the wall adapter. Use copper tape to do this. This will mean that your grape bunch will always remain on as long as the wall connected to power.

2) Connect the negative lead on a grape bunch to only one of the drain leads from the 3-pin MOFSET transistor of a single touch sensor. Once you have that specific touch sensor set up the way you'd like, you can turn these grape bunches on and off by simply touching the touch sensor.

We ended up dividing the grape bunches into three groups: 1) these sets of lights are always on, 2) these sets of lights turn on and off with the first touch sensor, and 3) these sets of lights turn on and off with the second touch sensor.

Step 14: Connect Each Speaker to Its Own Amplifier

As seen in the image above, you can see that there is a blue wire and a black wire coming out of the breadboard. These two wires are the ones that will be connected to either end of the wire on a butterfly speaker as explained in step 10. Keep in mind that we created 4 amps in parallel for 4 different speakers.

Step 1
Using the instructable from from step 10 as a guide, find where each audio output (blue wire) pin is on the breadboard for each amp you created. Connect a wire to these pins. Attach each of these pins to a different butterfly speaker.

Step 2
Next, we'll need to connect the unused wire on each butterfly speaker to the black wire (ground) we have coming from the breadboard.

Step 3
All of these speakers will be able to work with a single audio input source. Test to see if these speakers now work by hooking up your audio jack to a music player (phone, laptop, etc). Play a song! You can hear that the speakers are pretty loud.

Step 15: Create Your Own Touch Sensor

We wanted to use our signatures as a way to make a touch sensor. This is relatively easy.

Using some conductive paint, paint your signature (or any other object you'd like) on a section on the wall that is reachable by all people. Since we had two touch sensors, we drew out two signatures. Make sure each individual signature is connected on a single line, similar to how a word is connected in one single line when written in cursive. This will ensure that when a user touches the signature on any part, it will light the grape bunches on and off.

Then, connect these signatures to the touch input pin on the capacitive touch sensor you created in step 6 using copper tape. That's it! Once the conductive paint dries, you should be able to turn the grape bunches on and off by simply touching the paint signatures.

Step 16: Removable "Butterflights"

We made this section independently from the other parts of the wall. It's quite simple and can be done using 4 AA batteries. The idea behind these smaller butterflies is that the LED lights on them will light up when they are put onto the pane around a door. This makes your project a bit more fun and interactive.

Our door panes were already magnetic, so we simply needed to provide a power and ground line for the butterflies to be able to get power. If you do not have a magnetic surface, you can easily purchase some magnetic paint online, paint over the section you'd like to place the butterflies. After it dries, apply the copper tape over the paint. This section will be explained below.

Step 1
Take an LED and insert it into the middle of the butterfly. The butterflies we used were made of foam, so it was easy to do this.

Step 2
Cut off the negative (shorter) pin on the LED a little over halfway. Attach a tiny rare earth magnet onto the pin. It should automatically stick as the LED pins are magnetic. Apply a small dab of hot glue around the pin and magnet connection. Make sure it does not get between the pin and magnet connection, otherwise it will cause our butterflies not to light up.

Step 3
Take a 150ohm resistor and cut off about 3/4 of one side. Solder this short end to the positive (long) pin on the LED. Be sure to get the resistor as close to the body of the butterfly as possible without burning it.

Step 4
Cut off the excess of the LED pin.

Step 5
Cut off the longer end of the resistor as far down as possible. You'll want there to be a small but of wire remaining. Solder a dot onto this end of the resistor. Refer to the images above to see get a better idea of what this looks like.

Step 6
You may have to bend the resistor pin up to ensure that both pins find access to the wall. The idea is that both pins will need to touch the copper tape you will be placing on the wall. Each strand of copper tape will carry either positive or negative power, so we have to make sure the pins on the butterflies touch these strands. Make sure the distance between the pins are about the same for all the butterflies.

Step 7
Finally, we want to put the copper strands onto the wall so the butterflies can get power! In the last image, you can see that we've pulled out two strands of copper tape on the wall parallel to each other. You'll want these two strands to be as close as possible for the butterfly pins to be able to reach both. Ours were about 1cm apart. The top strand was designated to VCC and the bottom strand was designated to ground. 

Connect 4 AA batteries using a 6V battery pack. Attach the positive end of the batteries to the designated VCC copper tape strand. Attach the negative end of the batteries to the designated ground copper tape strand. Now, once you place the butterflies on the correct strands, the LED on their backs with light up!

Step 17: That's It!

If you have any questions, please leave in the comments section below. We'll try our best to help out!

Again, keep in mind that this is a work in progress project. We'll be updating this instructable as we go along and add more parts. Updates will be posted on the intro page. Good luck and happy hacking!
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