Flexible PCBs Make The Fins Of This Robotic Fish

We love a little outside-the-box thinking around here, and anytime we see robots that don’t use wheels and motors to do the moving, we take notice. So when a project touting robotic fish using soft-actuator fins crossed the tip line, we had to take a look.

It turns out that this robofish comes from the fertile mind of [Carl Bugeja], whose PCB motors and flexible actuators have been covered here before. The basic concept of these fish fins is derived from the latter project, which uses coils printed onto both sides of a flexible Kapton substrate. Positioned near a magnet, the actuators bend when a current runs through them. The video below shows two prototype robofish, each with four fins. The first is a scrap of foam with a magnet embedded; the fins did flap but the whole thing just weighed too much. Version two was much lighter and almost worked, but the tether to the driver is just too stiff to allow it to really flex its fins.

It looks like it has promise though, and we’re excited to see where [Carl] take this. Perhaps schools of tiny robofish patrolling for pollution?

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Don’t Flake on Your Fish—Feed them Automatically

We get it. You love your fish, but they can’t bark or gently nip at your shin flesh to let you know they’re hungry. (And they always kind of look hungry, don’t they?) One day bleeds into the next, and you find yourself wondering if you’ve fed them yet today. Or are you thinking of yesterday? Fish deserve better than that. Why not build them a smart fish feeder?

Domovoy is a completely open-source automatic fish feeder that lets you feed them on a schedule, over Bluetooth, or manually. This simple yet elegant design uses a small stepper motor to drive a 3D-printed auger to deliver the goods. Just open the lid, fill ‘er up with flakes, and program up to four feedings per day through the 3-button and LCD interface. You can even set the dosage, which is measured in complete revolutions of the auger.

It’s built around an ATMega328P, but you’ll have to spin your own board and put the feeder together using his excellent instructions. Hungry to see this feeder in action? Just swim past the break.

Can’t be bothered to feed your fish automatically? Train them to feed themselves.

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Big Mouth Billy Bass Channels Miley Cyrus

Here’s a Big Mouth Billy Bass with extra lip thanks to Alexa. If you’re not already familiar, Big Mouth Billy Bass is the shockingly popular singing animatronic fish designed to look like a trophy fish mounted to hang on your wall. In its stock condition, Billy uses a motion sensor to break into song whenever someone walks by. It’s limited to a few songs, unless you like to hack things — in which case it’s a bunch of usable parts wrapped in a humorous fish! Hackaday’s own [Bob Baddeley] combined the fish with an Amazon Echo Dot, connecting the two with an ATtiny84, and having Billy speak for Alexa.

[Bob] had a few problems to solve, including making Billy’s mouth move when there was audio playing, detecting when the Echo was on, moving the motors and playing the audio. After a bit of research and a lot of tweaking, a Fast Fourier Transform algorithm designed for the ATtiny was used was used to get the mouth moving. The mouth didn’t move a lot because of the design of the fish, and [Bob] modified it a bit, but there was only so much he could do.

It’s all well and good for the fish to lie there and sing, but [Bob] wanted Billy to move when Alexa was listening, and in order the detect this, the best bet was to watch for the Dot’s light to turn on. He tried a couple of things but decided that the simplest method was probably the best and ended up just taping a photo-resistor over the LED. Now Billy turns to look at you when you ask Alexa a question.

With a few modifications to the Dot’s enclosure, everything now fits inside the original mounting plaque and, after some holes were drilled so the Dot could hear, working. Billy has gone from just a few songs to an enormous entire library of songs to sing!

We’ve seen Alexa combined with Big Mouth Billy Bass before, but just demos and never an excellent guide like [Bob’s].  The nice thing about this guide is that once you’ve hacked the hardware, it’s a breeze to add new functionality using Alexa skills.

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Optogenetics for 100 Euros

Larval zebrafish, Drosophila (fruit fly), and Caenorhabditis elegans (roundworm) have become key model organisms in modern neuroscience due to their low maintenance costs and easy sharing of genetic strains across labs. However, the purchase of a commercial solution for experiments using these organisms can be quite costly. Enter FlyPi: a low-cost and modular open-source alternative to commercially available options for optogenetic experimentation.

One of the things that larval zebrafish, fruit flies, and roundworms have in common is that scientists can monitor them individually or in groups in a behavioural arena while controlling the activity of select neurons using optogenetic (light-based) or thermogenetic (heat-based) tools.

FlyPi is based on a 3D-printed mainframe, a Raspberry Pi computer, and a high-definition camera system supplemented by Arduino-based optical and thermal control circuits. FlyPi features optional modules for LED-based fluorescence microscopy and optogenetic stimulation as well as a Peltier-based temperature simulator for thermogenetics. The complete version with all modules costs approximately €200 with a layman’s purchasing habits, but for those of us who live on the dark side of eBay or the depths of Taobao, it shouldn’t cost more than €100.

Once assembled, all of the functions of FlyPi can be controlled through a graphical user interface. As an example for how FlyPi can be used, the authors of the paper document its use in a series of “state-of-the-art neurogenetics experiments”, so go check out the recently published open access paper on PLOS. Everything considered the authors hope that the low cost and modular nature, as well as the fully open design of FlyPi, will make it a widely used tool in a range of applications, from the classroom all the way to research labs. Need more lab equipment hacks? Don’t worry, we’ve got you covered. And while you’re at it, why not take a spin with the RWXBioFuge.

The Arduino Sleeps with the Fishes

[Eric Dirgahayu] wanted to explore underwater with some sensors and cameras. First, he needed a platform to carry them. That led to his Arduino-controlled swimming fish. The fish is made from PVC and some waterproof servos. From the video (see below) it isn’t clear how much control the fish has, but it does swim with an undulating motion like a real fish.

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Tissue-Engineered Soft Robot Swims Like a Stingray

We’re about to enter a new age in robotics. Forget the servos, the microcontrollers, the H-bridges and the steppers. Start thinking in terms of optogenetically engineered myocytes, microfabricated gold endoskeletons, and hydrodynamically optimized elastomeric skins, because all of these have now come together in a tissue-engineered swimming robotic stingray that pushes the boundary between machine and life.

In a paper in Science, [Kevin Kit Parker] and his team at the fantastically named Wyss Institute for Biologically Inspired Engineering describe the achievement. It turns out that the batoid fishes like skates and rays have a pretty good handle on how to propel themselves in water with minimal musculoskeletal and neurological requirements, and so they’re great model organisms for a tissue engineered robot.

The body is a laminate of silicone rubber and a collection of 200,000 rat heart muscle cells. The cardiomyocytes provide the contractile force, and the pattern in which they are applied to the 1/2″ (1.25cm) body allows for the familiar undulating motion of a stingray’s wings. A gold endoskeleton with enough stiffness to act as a spring is used to counter the contraction of the muscle fibers and reset the system for another wave. Very clever stuff, but perhaps the coolest bit is that the muscle cells are genetically engineered to be photosensitive, making the robofish controllable with pulses of light. Check out the video below to see the robot swimming through an obstacle course.

This is obviously far from a finished product, but the possibilities are limitless with this level of engineering, especially with a system that draws energy from its environment like this one does. Just think about what could be accomplished if a microcontroller could be included in that gold skeleton.

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Hackaday Prize Semifinalist: Better DIY Aquaculture

The theme of this year’s Hackaday Prize is ‘build something that matters’. For a lot of the teams entering a project, that means solving world hunger, specifically though agriculture. Grains are great, but proteins generally taste better and [Michael Ratcliffe] is focusing his project on aquaculture, or farming fish and other aquatic life.

The problem [Michael] decided to tackle is feeding fish at regular intervals according to water temperature, the age of the fish, and how much food is already floating in the tank. This is actually a difficult problem to solve; fish grow better when they’re fed more than once a day. Currently, most aquaculture setups feed fish once a day simply because it’s so time-consuming.

[Michael] is using Pis, Arduinos, USB cameras, and a lot of experience in automation and control systems to feed fish in the most efficient way. The possibilities of the project are interesting; the best research says a more efficient feeding schedule can translate into a 20% increase in production, which is a lot of extra food for the world.

You can check out [Michael]’s introductory video below.

The 2015 Hackaday Prize is sponsored by:

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