Introduction: ElectroPlush - Sleeping Teddy Bear That Wakes Up When Being Touched on the Belly

With this Instructable, you will be able to make the typical teddy bear plush toy and hack it with some circuitry in order to make it “wake up” when its belly is touched. ElectroPlush uses capacitive sensing on its belly, LEDs on its eyes, servo motors in its head, and an MP3 shield for sound. It is all connected together and programmed through two Arduinos, both embedded inside the teddy bear.


Stuffed Teddy Bear
2 x Arduino Uno 
SparkFun MP3 Player Shield
2 x 10 MegaOhm resistors
Mini Portable Speaker
Diffused Blue 10mm LEDs
High Torque Metal Gear Servo Motor

Final Result:

Step 1: Getting the Bear Ready for Hacking

Get a plush teddy bear like the one pictured above, and use scissors to make a cut onto its back, running from its head to its lower back. Get a box and use your hands to unstuff the bear until it is as empty as possible from inside.

Remove the eyes completely by cutting them. 

Step 2: Add a 10mm Diffused Blue LED on Each Eye.

Stick the legs of a 10mm diffused Blue LED ( on each eye with the Negative legs of both LEDs closest to each other, and the Positive legs on the outside.

Solder a wire from both Negative legs and connect them to the Ground of the Shield-less Arduino.
Solder a wire from both Positive legs to Pin13 of the Shield-less Arduino.

Step 3: Add the Serve Motor

Screw in a Servo Motor onto a thick plank of wood the size of the side of the bear's face, and screw in a solid piece of wood onto the arm of the Servo the 1 inch wide and the length of the head of the teddy bear (from back to nose).

Use a glue gun to stick that wood motor piece onto the side of the head in a way that makes the Servo's long wood arm run through the entire head, all the way through to the tip of its nose. Make sure to glue gun all the sides of the plank of wood for better results. 

Connect the Signal (yellow) cable to Pin11 of the Shield-less Arduino. 
Connect the Power (Red) cable to 5V of the Shield-less Arduino.
Connect the Signal (Black) cable to Ground of the Shield-less Arduino.

Step 4: Make an Arduino Board

Place both Arduinos side by side with a small PCB board in between onto a solid board. You may use screws to secure the Arduinos and the PCB on there. 

Step 5: Prepare Your MP3 Shield SD Card

Place the following files onto the root folder of an MicroSD Card and place it into the MP3 Shield.  These contain the sound files that the bear will make. 

Step 6: Complete the Circuit Board

Use this diagram to complete the circuit. The 2 capacitive sensing boards are actually pieces of conductive fabric connected to the belly of the teddy bear from the inside side by side to detect touch (or push) from the outside. 

Step 7: Upload Sketches to Arduinos

Unzip the package below, and upload BearFinal_ShieldLess to the ShieldLess Arduino and BearFinal_SoundVersion to the MP3 Shielded Arduino. You might need to adjust the capactive sensing threshold depending on the way you connected the conductive material and the type of teddy bear you are using. Change the int touchedCutoff to set the threshold to detect the capacitive sensor; higher numbers will decrease how capacitive the sensor is.

Step 8: Put the Stuffing Back in the Bear & Add a Zipper

Carefully start putting the stuffing back inside the teddy bear, and stitch a zipper onto the back opening you have created on the teddy bear's back for easy closure. 

Step 9: Wake the Bear Up!

Power up the Arduinos and the speaker. Make the teddy bear lay back and it should start making sleeping sounds. Touch its belly and his eyes should light up, his head should tilt upwards, and he should make sounds that are similar to that of waking up.