Droplet Watch Keeps Time Via Electrowetting

February 9, 2024 by Navarre Bartz 6 Comments

Hackers just can’t help but turn their sights on timepieces, and [Armin Bindzus] has designed an electrowetting-based watch.

Electrowetting is a way of changing the contact angle of droplets on a surface using electricity, and can be used to move said droplets. The liquid needs to be polar, so in this case [Bindzus] has used a red ink mixed with mono-ethylene glycol to stand out against the white dielectric back of the device. The 60 individual electrodes of the bottom section were etched via laser out of the ITO-coated glass that makes up the bottom plates of the face.

The top plate houses the small round pillars that keep the ink constrained to its paths. They are made of a photosensitive epoxy that is spin-coated onto the glass and then cured via the laser. The plates are put together at a distance of 0.23 mm with epoxy, but a small hole is left to insert the droplets and a filler liquid. An Attiny1614 microcontroller runs the show along with a DS3231 RTC. A 46V signal drives the droplets around their path.

It seems this project is a bit away from true wearable use, but perhaps [Bindzus] could make a desk clock first? If you’re interested in another ink-based, watch, how about this custom E-Ink Tank watch?

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Microfluidics “Frogger” Is A Game Changer For DIY Biology

January 16, 2017 by Dan Maloney 30 Comments

See those blue and green dots in the GIF? Those aren’t pixels on an LCD display. Those are actual drops of liquid moving across a special PCB. The fact that the droplets are being manipulated to play a microfluidics game of “Frogger” only makes OpenDrop v 2.0 even cooler.

Lab biology is mainly an exercise in liquid handling – transferring a little of solution X into some of solution Y with a pipette. Manual pipetting is tedious, error prone, and very low throughput, but automated liquid handling workstations run into the hundreds of thousands of dollars. This makes [Urs Gaudenz]’s “OpenDrop” microfluidics project a potential game changer for the nascent biohacking movement by offering cheap and easy desktop liquid handling.

Details are scarce on the OpenDrop website as to exactly how this works, but diving into the literature cited reveals that the pads on the PCB are driven to high voltages to attract the droplets. The PCB itself is covered with a hydrophobic film – Saran wrap that has been treated with either peanut oil or Rain-X. Moving the droplets is a simple matter of controlling which pads are charged. Splitting drops is possible, as is combining them – witness the “frog” getting run over by the blue car.

There is a lot of cool work being done in microfluidics, and we’re looking forward to see what comes out of this open effort. We’ve covered other open source efforts in microfluidics before, but this one seems so approachable that it’s sure to capture someone’s imagination.

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Laser Etched Surface Redefines Dry

January 22, 2015 by Sarah Petkus 89 Comments

Just the other day we stood in the kitchen making eggs, staring suspiciously at a long scratch carved in the center of the frying pan. With all the articles passing through social media prompting us to be wary of things in our environment that are supposedly killing us, Teflon included, I wondered to myself if humans would ever start coming up with solutions to daily problems… like sticky eggs, which don’t involve the use of complex chemicals. Alas, the universe responds with uncanny timing. A group of researchers led by [Chunlei Guo] from Rochester University’s Institute of Optics has recently published their development of a surface textured by lasers which repels fluid like a rubber ball… without any chemical treating involved. You really need to see this happen in the video below.

This physical magic trick gets its inspiration from nature, mimicking properties of surface tension from living things that repel water such as lotus leaves or butterfly wings. To achieve a similar effect, a precision laser is used to etch nanoscale patterns onto metal which change the surface properties in such a way that fluid molecules prefer not to stick. The benefit to texturizing a material’s surface as opposed to glazing it in some other repellant, is that the pattern becomes intrinsically part of the surface structure and will not fade over time the way a chemical seal will chip or flake. This hydrophobic technology could improve the way we keep surfaces sanitary as well as lend itself to new methods of frost prevention. Not to mention the dozens of other less important applications that we’ve just thought of for our own amusement.

In addition to creating the hydrophobic surface, the Institute of Optic has employed similar tactics to come up with a material capable of absorbing fluid and carrying it upward swiftly against gravity. With the knowledge of physics and the power of lasers combined, we’re glad to see humans coming up with smarter ways to manipulate the world we live in for a more comfortable daily life.

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