Video showing playing Pac-Man and Snake games with OpenDrop, a gadget that lets you manipulate and experiment with tiny droplets
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I Played Snake With Water - YouTube
Colorful droplets moving on a metal board.
At first glance they may look like CG, but these are real liquids.
OpenDrop is a research device that can freely manipulate various liquids, but Mould decided to play Pac-Man, Snake games, and other games with it.
Although the basic OpenDrop allows you to control droplets with a joystick, unfortunately you cannot play games on it as is.
It's certainly possible to connect droplets to create something like a snake in a snake game, but you'd have to write your own code to play the game.
So Mould decided to go to Switzerland and talk directly to Gordon, the developer of OpenDrop.
Mould was introduced to the lab and shown the various code layers and entry points where he could make his own changes.
As a result, we found that OpenDrop is basically an
Mould had no experience with Java, so he used Microsoft Copilot to
OpenDrop uses electricity to manipulate droplets by switching
Hydrophobicity is the physical property of having a low affinity for water; water is hardly attracted to the surface of a hydrophobic object, resulting in it beading up.
Conversely, hydrophilicity is a physical property that shows an affinity for water, meaning that the surface attracts water, causing it to stick flatly.
Each of OpenDrop's masses acts as an electrode, and when voltage is applied, the surface becomes charged.
The hydrogen atoms of a water molecule are positively charged and the oxygen atoms are negatively charged. When there is a negatively charged surface, the hydrogen atoms of the water molecule are attracted to the surface, while the oxygen atoms are repelled by the surface.
As a result, water molecules stick to the surface and do not leave it, meaning that a negatively charged surface is hydrophilic.
Scientists call this phenomenon, where applying a voltage to a surface changes how it wets,
In OpenDrop, droplets move by switching the charge of individual masses. For example, in the state below, the mass indicated by the arrow is charged, and droplets are attracted to that mass.
When the electrode was turned off and the adjacent square was charged, the droplet moved to the adjacent square. In this way, the droplet could be moved one square at a time.
OpenDrop allows for the manipulation of multiple droplets simultaneously.
However, when the droplets collide, they merge into one and cannot be separated again.
This may seem like a drawback, but in games like
To recreate Frogger in OpenDrop, Mould set up the droplets that act as cars to fold back on themselves at the left and right edges.
When the Frogger code is running, the droplets cannot be controlled with the joystick, so the frog droplets, which cross without touching the car droplets, are controlled with the arrow keys on the connected laptop.
Playing Frogger with OpenDrop. The red droplets are the cars that are obstacles, and the black droplets are the frogs that try to avoid them and cross the road.
He was able to skillfully manipulate the droplet that acted as the frog and make it cross to the edge.
OpenDrop also lets you recreate Pac-Man.
The yellow droplet acts as Pac-Man, chasing the target droplet.
If it hits a target droplet, it can be swallowed.
In the original Pac-Man, the size of the Pac-Man doesn't change no matter how much you eat, but in OpenDrop, the Pac-Man grows one size larger each time the droplets merge. So, in the end, you end up with a big Pac-Man chasing a small target.
This is fun in its own way, but different from the original.
On the other hand, in the snake game, the snake grows as it eats targets, so OpenDrop can reproduce this more faithfully.
Without any effort, the droplets on the OpenDrop would become round due to surface tension, making it impossible to create a snake shape.
However, OpenDrop comes with a transparent glass plate that can be placed over the droplet to shape the water.
A droplet sandwiched between glass plates flattens as shown below.
This makes it possible to create droplets of various shapes.
OpenDrop allows for the manipulation of different concentrations of liquids to automate the dilution process and perform testing, but more importantly for Mould, it allows for the creation of 'snake' shapes.
Usually in snake games, when you eat a 'fruit' that appears on the screen, another 'fruit' will randomly appear in another location.
To replicate this, Mould designed a design in which the snake would eat a fruit, then pause for a period of time during which a new fruit would be moved into place.
Here's what playing the snake game with OpenDrop looks like: The snake heads towards the fruit surrounded by a red frame at the bottom right of the board.
Snakes eating fruit.
Then the fruit was placed in a different location.
By repeating this process, you can make the snake bigger and bigger.
'OpenDrop' can be purchased from the official website below, and the basic ' OpenDrop V4 ' costs 975 euros (approximately 169,000 yen). In addition, shipping to Japan requires a shipping fee of 68 euros (approximately 11,800 yen), and additional taxes and customs fees are also borne by the purchaser.
OpenDrop Digital Microfluidics – GaudiShop
https://gaudishop.ch/index.php/product-category/opendrop/
In addition, the hardware and software designs for OpenDrop are publicly available on GitHub, allowing users with the necessary expertise to create their own devices of any shape.
GitHub - GaudiLabs/OpenDrop: Open Source Digital Microfluidics Bio Lab
https://github.com/GaudiLabs/OpenDrop