Aiwen Wang-Huddleston
Chris Alden
David MIller
Michael Doherty


TweetGrass (twitter + wheat grass) is a playful, interactive installation designed to encourage sustainable living habits.

Introduction to Physical Computing

Our initial concept was simple: community members can tweet their sustainable living actions to a physical screen that represents each tweet as a cloud. Once a critical mass of clouds have gathered, it starts raining on-screen, which triggers a real watering system to rain on a box of wheat grass located underneath the screen. TweetGrass thus features two related types of information: 1) the tweets display specific ways in which people contribute to their sustainable living and working environments, and 2) the health of the tweetgrass, which can be clipped for juice, indicates whether more contribution is needed. As community contributions grow, so does the tweetgrass. Or, if people stop contributing, then the tweetgrass dies into a memorial.

Our initial target audience is the ITP community, but TweetGrass is also a scalable project that ideally can be installed in existing communities such as schools, local parks, offices, etc.

User Scenario
The TweetGrass interaction is quite simple:

Step 1: Help your environment (e.g. shop at a thrift store, use a reusable water bottle, throw someone else’s garbage away, etc)

Step 2: Tweet your contribution to TweetGrass (#tweetgrass)*

Step 3: Watch the screen’s tweet-clouds grow bigger until it reaches a critical mass and starts raining real water onto community wheat grass

Step 4: Harvest your tweetgrass for some super-healthy juice shots!

*Option: Those who don’t wish to twitter can also participate by throwing away their recycling in the TweetGrass recycling bins located underneath the TweetGrass stand. Each time they recycle an item, the TweetGrass bin will register their action and add a cloud to the screen.

TweetGrass consists of three main parts: a screen displaying clouds of incoming tweets, a box of wheat grass underneath the screen which also includes TweetGrass recycling bins, and an irrigation system for the wheat grass.

1) Screen: for ITP30, we used a plasma screen and the Mac mini to receive tweets, run processing and display the clouds

2) The wheat grass stand is made of wood, which will be stained and water-proofed, and includes a built-in box for recycling. A PIR-sensor will be located above (on the "ceiling" of) the recycling bin to register a moving object thrown into the bin. The TweetGrass stand itself will include separate compartments for the arduino and the irrigation system.

3) The irrigation system is made of a bucket of water, clear tubing, clear pipe, a pump, and one mister. The bucket of water will be lidded, with one tube coming from a hole in the top of the lid. This tube connects to one end of the pump, which will be controlled by a relay connected to the arduino. Water will come out of another tube on the other side of the pump, and this tube is joined to a clear pipe. The pipe will have a single mister attached to the other end, which will provide minimal water action. We used PVCglue, silicone sealant, and teflon tape to join all the parts. Water will be delivered for 20-30seconds at a time, and the frequency will depend on how many people are tweeting.

For our first prototype for ITP30, we were able to get the tweet-screen processing program to trigger the irrigation system successfully. However, our capacitance sensor for the TweetGrass box (designed for non-Twitter users) never stabilized and it also became apparent that we would have to tweak our irrigation system to deliver the water more evenly and at a higher water pressure.

Subsequently, we designed our second prototype to be installed for the Founders Club event at the NY Stock Exchange. Unfortunately, 10days prior to installation, the Stock Exchange informed the event planner that they were uncomfortable with having an irrigation system on the floor and that wheat grass would not fit into their Winter White Wonderland theme! Nonetheless, we have re-designed the irrigation system so that it delivers water as mist and we replaced the solenoid valve with a pump. We also built another TweetGrass box stand that could store the arduino and relay within the box while keeping it separate from the pump and watering system.

We're very excited by the possibility of testing out a working prototype at the ITP Winter Show!