# Word Reveal Play With Thermochromic Color

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-I am presenting my experience with thermochromic pigment to reveal the word, 'welcome'.

I live in New York, and I order a lot of delivery foods. I sometimes think that those people who deliver food for us, either it's raining or snowing, are amazing.

I can never express enough of how much I appreciate their effort, besides paying tips.

So I thought of a way I could maybe communicate with them without actually saying anything outloud.

(because what they do is just hand in the food, and leave immediately).

Then I came with this idea to reveal the word using thermochromic color, a new technique I learned at school.

I planned to have a photo frame with a cotton piece painted with playful colors and then painted with black thermochromic paint.

And underneath the cotton layer, I would have a 'welcome' word sewed on another cotton layer.

Materials used in this project:

- Arduino
- Ultrasonic Sensor
- Cotton pieces
- Wires
- Thermochromic Color Pigmen
- Clear Acrylic Paint
- Colorful Acrylic Paints
- Mosfet Heating Circuit (connector between Arduino and the sewed copper wires)

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## Step 1: Step 1: Fill the Cotton Piece With Acrylic Paints

First thing you want to do is color the cotton with 'colorful' acrylic colors.

You do this so that when the copper wire is heated, these colors can appear under the black thermochromic color.

In order to paint thermochromic color on top of these acrylic paints, you must dry it thoroughly and completely.

So let it sit aside while you do the next steps.

## Step 2: Step 2: Make a Heating Element

I did the word 'welcome' by sewing copper thread in chain-sewing technique.

If the copper thread is flat on the surface, it might not have a very strong effect on thermochromic color.

I sewed the word all the way but I realized there was an error. Please refer to the second photo (right one)

Second photo: In order to NOT make a short circuit, you must not connect the areas where I marked. Put a piece of tape or make it not intersecting at all.

## Step 3: Step 3: Test Ultrasonic Sensor

Test if the ultrasonic sensor is working or not.

Connect ultrasonic sensor to Arduino and test it with LED lights possibly.

Code for arduino below:

int trigPin = 9;

int echoPin = 10;

long duration; int distance; void setup() { pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output pinMode(echoPin, INPUT); // Sets the echoPin as an Input Serial.begin(9600); // Starts the serial communication } void loop() {

digitalWrite(trigPin, LOW); // Clears the trigPin delayMicroseconds(2);

// Sets the trigPin on HIGH state for 10 micro seconds digitalWrite(trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW);

// Reads the echoPin, returns the sound wave travel time in microseconds duration = pulseIn(echoPin, HIGH);

distance= duration*0.034/2; // Calculating the distance

// Prints the distance on the Serial Monitor Serial.print("Distance: "); Serial.println(distance);

Serial.print("Distance: ");
Serial.println(distance);

}

## Step 4: Step 4: Play & Test Thermochromic Color

Before actually using thermochromic color, I took time to play and test with thermochromic color.

I took little pieces of paper, colored it with colorful colors.

And on top of that, I tested the amount of thermochromic pigment with different amount of water to see how much is appropriate to cover the colors completely.

## Step 5: Step 5: Thermochromic Color

If your acrylic colors are completely dried, it is time to cover the top of Acrylic paints with black thermochromic paint.

Mix in the following(with the right amount of each like you tested) :

- Clear acrylic base

- Black thermochromic pigment

- Little bit of water

## Step 6: Step 6: Connect the Heating Element to Arduino

First photo is the heating circuit you need to use in orer to heat up the copper wire when it's connected to Arduino.

## Step 7: Step 7: Code & Ultrasonic Sensor

This is the code that will allow ultrasonic sensor to measure the distance and then activate the heating circuit to heat up.

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