Realistic Beating Heart With Arduino

Materials:

• Smooth on Dragon Skin 10NV Silicone
• 4 inch Human Heart Mold - we bought ours here
• Metal Gear Micro Servo
• 5V DC Power Supply or 5V Battery Pack
• Super Glue (Cyanoacrylate Glue)
• Non-Metal Disposable Container (for mixing silicone)
• Wooden Stir Stick
• Latex Free Gloves
• Arduino Uno
• Exacto Knife or Box Cutter

Lay down a tarp or trash bag to protect your work area during the casting process. Make sure your mold will be stable throughout the curing process, we used a food storage container to hold ours while we made the cast.

Put on your latex free gloves and mix your Dragon Skin 10 NV or other silicone according to the manufacturers instructions. Only mix as much silicone and you intend to use for your cast. We chose Dragon Skin 10 NV because it does not require vacuum degassing during the molding process, check with the manufacturer for more information about the silicone you are using.

Pour your thoroughly mixed silicone into your heart mold. Once the mold is filled, leave it undisturbed during the curing process. Curing time depends on the temperature in your workspace. At room temperature, Dragon Skin 10 NV takes 75 minutes to cure, we recommend leaving things to cure for at least two hours.

Note: If you want to incorporate pigment into the heart, be sure to purchase it alongside the silicone and mix it in before adding the silicone mixture to the mold.

Once the heart is cured, use something blunt like a butter knife to weaken the seal between the silicone and the mold. Then, gently lift the heart out of the mold from the wide base, being careful not to damage the mold while removing the heart.

After removing the heart, use your exacto knife to trim any excess silicone from the edges. Cut into the center cavity, flat side up, to make a space large enough to embed the servo motor according to the diagram above. Be sure to make a slightly deeper cut (1/4 inch) where the head of the servo motor will lay in order to give the arm a full range of motion.

Next, cut a channel from the top of the servo cavity up and out the largest artery to hold the wires coming off of the motor. During this process, make sure to cut no more than 1/4 inch deep. Cutting too deep could damage the structural integrity of the artery. Save the silicone removed from the channel, as we will use it later to cover and secure the wires.

Connect the servo motor to your Arduino according to the circuit diagram. Upload the heartbeat code to the board and calibrate the heartrate and actuating angle to your system. Place the servo motor into the heart, pressing it into the cavity to test how it will work when the system is glued together.

Check that the space is deep enough that the motor lays flush with the back of the heart. Confirm that the angle of motion or the servo arm is small enough to not damage the heart, but large enough to create the desired effect. Make any adjustments to the cavity and code as needed.

When you are ready to permanently affix the motor, add several lines of super glue to the back of the motor and press it into the cavity. Only put glue on the motor casing, do not put glue onto the actuating arm. Make sure to hold the motor still in the heart for at least 2 minutes while the glue cures. Once the motor is affixed, run the wires through the artery and glue the silicone cover from step 2 back into the canal to secure the wires.

Give the heart power by attach the 5V wall converter to the Arduino. For a portable beating heart, utilize a 5V lithium ion battery and power assembly for the board you are using.

Experiment with ways to integrate your new prop into your costume, decor, or performance. The applications of your project are only limited by your imagination, follow your heart!