Introduction: Proximity Sensing Origami Flower

About: art/tech/craft hacker and member of Ace Monster Toys hackerspace in Oakland, CA

Origami is the traditional Japanese art of paper folding.  In this project, with a little help from an Arduino, you can bring your origami into the 21st century and make it an interactive art!

The result shown here uses Bare Conductive paint to give an origami flower proximity sensing powers.  When you put your hand close by, it triggers a small vibrating motor, and the flower wiggles around to say "hello!".

Submitted by Ace Monster Toys Hackerspace in Oakland, CA for the Instructables Sponsorship Program

Step 1: Tools & Materials

Let's get started by gathering the necessary materials:
  • Origami Paper (or printer paper cut into a square)
  • Wire Stripper
  • Pliers
  • Scissors
  • Paper clip
  • copper wire
  • electronics prototyping breadboard
  • arduino board and arduino sketch software
  • Capacitive Sensing arduino library (from here)
  • small vibrating motor as from a cell phone battery
  • Several 10M Ohm resistors
  • Bare Conductive paint
  • paint brush
  • computer for loading code onto Arduino (not shown)
  • Attached Arduino sketch (rename from ProxFlower.ino.txt to ProxFlower.ino)
  • OPTIONAL: for more flower flair, add connect an LED in addition or instead of the motor

Step 2: Make and Prepare an Origami Flower

The first step is to make an origami flower or other origami/paper object to which you want to add proximity sensing powers.

The flower below was created by following the instructions presented at this link.  It is the traditional way to fold a Lily.

Once the flower is completed, cut off the bottom of the flower to make a place to thread the vibrating motor leads through.

Finally, paint the petals with conductive paint, making sure that the entire painted surface is continuous across the petals.  As I did this project, I painted the flower fairly late in the process and used a painted post-it note to test out the circuit first, so you will see the flower as unpainted through most of the Instructable.

Step 3: Assemble Circuitry

The basic idea for the proximity sensor circuitry comes from Bare Conductive's tutorial.  I have modified their Arduino sketch to include a control for turning the vibration motor on and off.

Initially, I started with a test proximity sensor made from a post-it painted with Bare paint.  Once I was able to verify that my sketch was working, I was then ready to include the origami flower.

The circuit is fairly simple:  I connected a wire from pin 4 on the arduino to the breadboard.  Then, I connected 3 10MOhm resistors in series (to give 30MOhm resistance), and connected the end of this chain to pin 2 on the arduino.  Finally, the end of the resistor chain was connected to a paper clip using a copper wire.  I then connected the paper clip directly to the paper painted with conductive paint, which acts as a capacitor with air as the dielectric and my hand as the second conductor.  This follows Bare's tutorial almost exactly.  

Then, I connected the motor (embedded in the flower) to the GND pin and pin 13.  Pin 13 is convenient because most Arduino boards have an LED connected to Pin 13 by default and this allows you to see what is going on.

Step 4: Upload Arduino Sketch, Calibrate, and Adjust System

Initially, I used a test prox sensor pad to test and adjust how the system works.  First, I uploaded the arduino sketch and opened the "serial monitor" tool.  The sketch prints out the output from the prox sensor to the serial window.  Ideally, you should see the numbers get much larger in the serial monitor if your hand is present over the proximity sensor than if it is not present.

There are three considerations here: the value of the resistors, the surface area of the painted region, and the threshold of the prox sensor that you want to react to.  If you are finding that you have to get too close to the sensor to get a large value, then you can either increase the painted area or increase the value of the resistors (by adding another one to the circuit in series, for example).  Once you are seeing a large difference between hand present and not present, then you just have to decide what number signifies that "someone is near" and use that as a threshold to turn on the vibrational motor.  

Initially, I wasn't seeing much of a difference between my hand being there and not... the values seemed random.  I decided to increase my resistor value from 10MOhm to 30MOhm.  Then, I was seeing numbers in the 50s-80s with no hand present and with my hand there I saw 500's or so.  I chose 500 as my threshold value.

NOTE: In the video I keep saying "conductive sensor", but really I mean "capacitive sensor".  

Step 5: Putting It All Together

Once the threshold has been tested and calibrated with the final capacitive origami object, you are ready to go!  Upload the final Arduino sketch, and find someone to "stop and smell the flowers"!

As an addition, you could embed an LED into the flower as well, or make several flowers to connect up to the Arduino.
Ihope you are able to replicate this project at home and take it in your own direction.

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