Move one droplet
Build a 3 × 3 array and test whether one droplet moves between neighboring electrodes, including downward and sideways moves. Use the result to choose the electrode geometry and surface materials.
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How to Make (Almost) Anything / 2026
Digital Microfluidics Tetris
A proposal for a physical game display made of programmable liquid droplets, where pixels can move, meet, and change shape.
00 / The spark
From a building
From a building
to a droplet.
If Tetris can be as big as a building, could it fit inside a tiny board?
This idea started with Microfluidic Bubble Logic by Manu Prakash and Neil Gershenfeld. I was fascinated by the idea that moving bubbles could carry information and perform logic operations.
While thinking about microfluidics, I remembered the giant Tetris game on MIT's Green Building. That led me to digital microfluidics, which offers a way to control individual droplets electronically. I want to explore what happens when the pixels in a game are made of liquid.
01 / What does it do?
A game board
A game board
made of liquid.
I want to build a small physical display using digital microfluidics (DMF), with colored droplets as its moving pixels.
My eventual goal is a playable, Tetris-inspired game controlled by buttons or a joystick. The board will use electrowetting on dielectric (EWOD). It is a technology that uses an electrical voltage to change a surface from water-hating to water-loving.
Activating neighboring electrodes in sequence will guide a droplet across the board. The board will lie horizontally, so a piece's “falling” motion will be a programmed sequence of moves toward the bottom of the grid. MIT's Programmable Droplets project is a useful reference for this approach.
Eventually, I would like to coordinate several droplets into game pieces and explore merging and row clearing. Clearing a row will require somewhere for the liquid to go, such as a collection area. For the first prototype, I will focus on reliable movement.
02 / Course roadmap
A semester of
A semester of
small moves.
The milestones follow the 2026 HTMAA syllabus. They are a starting point and may change after the first droplet tests.
CAD & cutting
Develop the proposal, sketch the board in Fusion 360, and cut prototype spacers or gaskets.
Embedded programming
Prototype the grid-based game logic and electrode-control sequences.
3D printing
Print a small holder for the test board and controls.
Electronics
Design and fabricate a 3 × 3 electrode array and its control electronics. Begin testing dielectric and hydrophobic surface layers.
Input devices
Add buttons or a joystick for manual droplet control.
Output devices
Integrate the high-voltage driver and demonstrate repeatable droplet movement.
Wildcard & casting
Refine the surface treatment and enclosure seals, and review whether scaling up is practical.
Interfaces
Connect the game logic to the board and add a simple interface for testing.
Integration & presentation
Assemble, test, and document the prototype. Finalize additional orders by Dec 4 and prepare for the Dec 15 presentation.
03 / Spiral development
Start with one.
Start with one.
Then scale.
Make it interactive
Add physical controls and a simple falling-droplet game. Aim for at least 18 successful moves out of 20 commanded one-cell moves, without manually repositioning the droplet.
Expand toward Tetris
Use a parametric Fusion 360 layout to explore an 8 × 12 board. Then redesign the routing and driver capacity, test coordinated droplets, and explore a way to clear or reset the board.
Minimum outcome
A small board on which a player can reliably steer a real droplet.
04 / Potential inventory
| Item | Quantity | Likely source |
|---|---|---|
| XIAO RP2040 or ESP32 controller | 1 | Fab inventory |
| Electrode PCB and test boards | 2–3 boards | Fab inventory |
| Buttons, connectors, passive components, and logic-level interfacing | 1 set | Fab inventory |
| Printed enclosure, spacers, and adhesive | 1 set | Fab inventory |
| High-voltage electrode driver | 1 | Likely additional purchase |
| Suitable high-voltage supply and supporting power parts | 1 set | Likely additional purchase |
| Dielectric films and hydrophobic surface materials | Samples / roll | Likely additional purchase |
| Silicone oil, dye, and liquid-handling supplies | Small amounts | Likely additional purchase |
05 / Prior work
Droplets already know how to play.
Dancing Drops
Wedyan Babatain used electromagnets to move magnetic liquid-metal droplets. The project is a reference for building a droplet-control platform, although its actuation method differs from EWOD.
See the project ↗Snake with water
Steve Mould demonstrated how moving water droplets can become an interactive game. It is especially close to the experience I want to create.
See the demonstration ↗Programmable Droplets
MIT explored EWOD for displays, play, and other interfaces through droplet movement, merging, splitting, and shape changes. The related DropletIO project investigates integrated actuation and sensing.
See the research ↗