Did you know you can generate electricity from the “metal-breathing” anaerobic bacteria found in ordinary mud? Having no oxygen to breathe, these bacteria produce energy for their growth by transferring electrons to clumps of rust and other metal oxides, in a process called dissimilatory metal reduction. Dr. Ashley Franks, director of K–12 outreach at the Geobacter Project and senior lecturer at Latrobe University, has extensively studied these bacteria, and shared his how-to for creating your own microbial fuel cell to harness this energy on the pages of MAKE Volume 30.
From his intro:
A microbial fuel cell (MFC) does the same thing as a battery: drive electrons from an anode to a cathode through chemical oxidation/reduction reactions. What makes MFCs different is that they run on organic substrate and bacteria.
“Metal-breathing” (Geobacter) bacteria at the anode carry out the oxidation reaction, converting plant and animal debris in the mud into electricity and carbon dioxide. Electrons flow through wires to a cathode sitting in water above the mud, where they combine with oxygen to complete the circuit. The bacteria are highly efficient in this arrangement and can produce electricity continuously for many months or even years.
Experimental MFC-powered buoys now operate in the Potomac River, using naturally occurring bacteria in the mud to measure and transmit meteorological data. These “Benthic Unattended Generators” (BUGs) have worked for several years with no decrease in power output (see http://nrl.navy.mil/code6900/bug). Geobacter species possess other useful abilities, such as the ability to respire radioactive uranium and remove it from ground water. They have proven versatile and effective in cleaning up areas contaminated with uranium or organic pollutants.
Until recently, home automation was gimmicky, finicky, and user-hostile. But today, thanks to a new crop of devices and technology standards, home automation is useful, fun, and maker-friendly. In the special section of MAKE Volume 30, we’ll show you: how to flip any switch in your home with a smartphone, home automation without programming, controlling your HVAC with an Arduino, a webcam security system, and a wall-mounted Notification Alert Generator (NAG) that plays timely reminders as you walk by. Plus, you’ll build a Yakitori Grill, a robust R/C flying-wing airplane, sturdy furnishings from PVC, and more!
Our latest Weekend Project combines two projects into one to create a piece of wearable fashion technology, the Solar Joule Bracelet! A joule (pronounced like “jewel”) is a unit of energy – in this project we’ll be sourcing that energy from the sun with the aid of PIN photodiodes wired in series, which along with a supercapacitor and Schottky diode will function as a solar battery (we built a similar project previously, the Solar USB Charger). This energy will then be stolen by the “joule thief” circuit, consisting of a choke (inductor coil), transistor, capacitor, and resistor all wired together. Oscillations through this circuit will eventually exceed the adjoined LED’s forward voltage rating, causing the LED to shine like a jewel! These oscillations occur in bursts, but once fully charged the oscillations will happen so fast the LED will glow continuously.
Cool, simple tutorial from one Kyle Wilson. Ingredients: One set drop-style handlebars, one matching quill stem, a short pipe nipple to match, a pipe flange, a couple screws, and some bar-tape and -ends (or their improvised equivalents). [Thanks, Katherine!]
Redditor jennyleighb’s roommate built a seascape from Lego with a Super Mario Bros. theme. I’m not sure how much the fish appreciate it, but this is definitely the most geek-tastic fish tank I’ve ever seen.
James Bruton of Southampton, UK, wrote in to share his dollar store (or 99p store in the UK!) Arc Reactor — it looks great!
Since I’m building an entire Iron Man suit, I decided that I should really build an Arc Reactor prop. This is intended to be like the Arc Reactor in the original Iron Man movie, since it won’t actually get installed in the suit. Pretty much all of the items I used came from the 99p store, with the exception of some wire and a few electronic components.
The items I bought are: an LED light with batteries, sink strainers, some pins in a circular holder, a solar garden light.
NASA JPL researchers present a 250-mm diameter omni-directional anchor that uses an array of claws with suspension flexures, called microspines, designed to grip rocks on the surfaces of asteroids and comets and to grip the cliff faces and lava tubes of Mars.
With temperatures on the rise and the first day of summer only 3 weeks away, pool season is just about upon us. Back in MAKE Volume 23, rocket engineer Edward Hujsak shared an efficient, low-cost, safe, and easy way to warm your pool. His project is the Lily Pad pool warmers, and they’re essentially made of hula hoops covered with black polyethylene film. The how-to is freely available for you on Make: Projects, where community member Daniel Busby commented, sharing the video he made of his Lily Pad build. The only difference between Edward’s instructions and Daniel’s build is that Edward used a soldering iron to spot weld the plastic to the hoops, and Daniel chose to use a household iron. Here’s Daniel’s video:
In his article, Edward also included an interesting sidebar titled “The Pool Owner’s Dilemma”:
The thermal behavior of swimming pools is complex, due to a number of factors that act to cool the water, while the sun and artificial means work to keep the water warm. Cooling forces are at work day and night, and include evaporation, conduction into surrounding soil, air current effects, and nighttime longwave (infrared) radiation into space.
Gas-fired heaters are the most common pool warmers, but up-front costs for equipment and installation run into the thousands of dollars. And then there’s the operating cost and the price of natural gas. These heaters are prodigious polluters; for an average-sized pool, a 1°F rise in temperature results in spewing 50lbs to 60lbs of carbon dioxide into the atmosphere.
Roof-mounted solar heaters are a second option. Water from the pool is pumped through solar-heated heat exchangers and returned to the pool. Like gas-fired heaters, solar heaters are costly and are generally unsightly. They’re also a problem in frost-prone areas.
Bubble plastic blankets are passive devices that cover the pool. They function mainly as water conservation devices by inhibiting evaporation, thus slowing evaporative cooling. They also block nighttime radiation loss. Manufacturers claim these blankets also behave as warmers, transmitting additional energy from the sun into the water. But water already has a very low albedo (ratio of incident energy to reflected energy). It’s about .10 for deep water, a bit higher in white-bottomed pools, and it’s doubtful that bubble covers improve on that. (The low albedo of water is the reason for the great concern about the receding of the polar ice caps. Open water warms much more rapidly than ice fields, which reflect more than 80% of the sun’s energy.) Moreover, pool blankets destroy the aesthetic appeal of a backyard pool; they’re hard to manage, difficult to clean, and unsafe where small children are around; and they’re often dumped after a single season.
I was at my prosthodontist’s office the other day getting some work done and the conversation turned to what I do for work. I told my dentist, Vu Huynh, DMD that I worked as a Web Producer for MAKE magazine. He almost dropped the cheek clamps (not a real thing…). He’s a subscriber and a maker. He told me about some of the projects that he’s worked on. One of his favorite builds was the Squelette, a bare-bones amplifier project that we featured in Volume 23. Vu took a few liberties in his build that I found interesting. For instance, he separated the power supply from the rest of the circuit to minimize noise. It’s a nice little amp, and a great project for those new to electronics. Sadly, even with my increased cred with the doc, I didn’t get an extra lollipop — or a discount on the bill.
In the menagerie of Craig Venter’s imagination, tiny bugs will save the world. They will be custom bugs, designer bugs — bugs that only Venter can create. He will mix them up in his private laboratory from bits and pieces of DNA, and then he will release them into the air and the water, into smokestacks and oil spills, hospitals and factories and your house.
Each of the bugs will have a mission. Some will be designed to devour things, like pollution. Others will generate food and fuel. There will be bugs to fight global warming, bugs to clean up toxic waste, bugs to manufacture medicine and diagnose disease, and they will all be driven to complete these tasks by the very fibers of their synthetic DNA.
Impressive article, I think this might kick off some popularization and interest in “biohacking”.
Vulpestruments just announced the completion of the Droneitar, a two-stringed instrument that has drone strings powered being continuously plucked by a string attached to an electric motor. In fact, the coils from another electric motor are used as a pickup for the device. Rich Stephenson demonstrates the sonic possibilities of the Droneitar in the video.
The Droneitar is made entirely from repurposed materials, from the wood that makes up the body, to nails being used as frets. Despite this, the instrument has a great, vintage look, and the sound speaks for itself.
Did you know? You can make pencil drawings reactive to touch for use with your projects! It’s really easy, and gives you a lot of flexibility in making interfaces for whatever microcontroller project you’re making.