• Lundi, Mars 31, 2014 - 09:00
    This incredible video shows rarely seen footage of “slow” marine life

    Daniel Stoupin made this incredible time lapse video of rarely seen footage of “Slow” marine life in the Great Barrier Reef. We highly recommend watching this in full screen HD because the visuals are truly stunning.

    The most important living organisms that play the key functions in the biosphere might not seem exciting when it comes to motion. Plants, fungi, sponges, corals, plankton, and microorganisms make life on Earth possible and do all the hard biochemical job. Similarly to all living things, they are dynamic, mobile, and fundamentally have the same motion properties as us. They grow, reproduce, spread, move towards source of energy, and away from unfavorable conditions. However, their speeds happen to be out of sync with our narrow perception. Our brains are wired to comprehend and follow fast and dynamic events better, especially those very few that happen at speeds comparable to ours. In a world of blazingly fast predators and escaping prey events where it takes minutes, hours, or days to notice any changes are harder to grasp.

    “Slow” marine life is particularly mysterious. As colorful, bizarre-looking, and environmentally important as we know corals and sponges are, their simple day-to-day life is hidden. We know some bits about their biochemistry, corals’ interaction with zooxanthella algae, their life cycles, and systematics. Unfortunately, it’s hard to tell what we don’t know about the rest, and particularly when it comes to interaction with other organisms happening over long periods of time.

    Here’s some info on how he made the video from his upload on Vimeo:

    To make this little clip I took 150000 shots. Why so many? Because macro photography involves shallow depth of field. To extend it, I used focus stacking. Each frame of the video is actually a stack that consists of 3-12 shots where in-focus areas are merged. Just the intro and last scene are regular real-time footage. One frame required about 10 minutes of processing time (raw conversion + stacking). Unfortunately, the success rate was very low due to copious technical challenges and I spent almost 9 long months just to learn how to make these kinds of videos and understand how to work with these delicate creatures.

    Read more.

  • Lundi, Mars 31, 2014 - 08:00
    Swapping Streetlights with Luminous Trees

    Daan Roosegaarde, a Dutch designer captivated by the merging worlds of nature and technology, is developing a plan to replace traditional streetlights with glowing plants and trees in an on-site installation, from dezeen.

    Dezeen and MINI Frontiers: Dutch designer Daan Roosegaarde is exploring ways of using the bio-luminescent qualities of jellyfish and mushrooms to create glow-in-the-dark trees that could replace street lights.

    In this movie filmed at SXSW in Austin, Roosegaarde explains how: “In the last year I really became fond of biomimicry.”

    “What can we learn from nature and apply to the built environment, to roads, to public spaces, to our urban landscape?” asks Roosegaarde.

    Biomimicry is the method of imitating models and systems found in nature to solve complex design issues. One of the biological phenomena that fascinated Roosegaarde was how animals like jellyfish and fireflies generate their own light.

    “When a jellyfish is deep, deep underwater it creates its own light,” he says. “It does not have a battery or a solar panel or an energy bill. It does it completely autonomously. What can we learn from that?”

    Roosegaarde’s interest in biomimicry led him to collaborate with the State University of New York and Alexander Krichevsky, whose technology firm Bioglow unveiled genetically modified glow-in-the-dark plants earlier this year.

    Krichevsky creates the glowing plants by splicing DNA from luminescent marine bacteria to the chloroplast genome of a common houseplant, so the stem and leaves emit a faint light similar to that produced by fireflies and jellyfish.

    Roosegaarde is now working on a proposal to use a collection of these plants for a large-scale installation designed to look like a light-emitting tree.

    Glowing Tree Roosegaarde Dezeen 644

    Read more.

  • Lundi, Mars 31, 2014 - 08:00
    Hacker-in-Residence: Interactive Garments

    Happy Monday friends – it’s time to welcome a new hacker to our ranks! Say hello to Matt Pinner.

    alt text

    Hello, Matt Pinner!

    Matt is here for three weeks and has already been hard at work in our Engineering department. Let’s learn more about Matt.

    Can you share your background, interests, and some favorite past projects? What and where is your current position?

    I create environments where people get to play, interact, and ultimately learn.

    I’ve been all over the world and got into computers with the dream of working from the top of a mountain. It turns out I enjoy interaction and collaboration too much for that. I’ve been engrossed in several startups because I enjoy working hard as part of a small, passionate teams. My skill in application scalability, performance optimization, and security grew into a love of hardware and distributed systems.

    Specializing in wearable computing and mobile devices has allowed me to have really nerdy conversations in traditionally boring places: street corners, nightclubs, and in line at the market. I love Science, Technology, Engineering, Art, and Math (STEAM), and find it especially rewarding to open people’s minds to the possibilities they can create with even a minimal grasp of technology. I’ve experimented with adding sensors, batteries, and lighting to every part of the body in a effort to understand how calling attention to our parts can affect how we move.

    Most recently I’ve been 3D-printing LED buttons for use in my garments. They can be sequenced to express the theme of an event, coordinate with others, or be reactive to their surroundings. Through sensing ambient conditions, other people’s presence, and the emotional state of the wearer, a garment can more gracefully integrate the wearer into their surroundings. Subtlety is the name of the game and I’m continually striving to integrate people with technology, not distract or withdraw them with it.

    CrashSpace, a Hackerspace in Los Angeles, has been my home and studio for over 4 years. I made everyone’s favorite soldering unicorn and our mascot, Sparkles. It has been a joy to share her with the world and a valuable tool around the shop. You can build your own Sparkles here!

    alt text

    Sparkles herself, courtesy of CrashSpace

    I made an internet-connected Little Free Library as an experiment in generative art and public interactivity. It is still the most sophisticated we’ve seen. Not only does it look like miniature version of our space, but tracks deposits and withdrawals while lighting momentarily to aid in book selection. On our busy street it has shared tens of thousands of books:

    alt text

    The CrashLibrary in action

    Checkout my interactive fashion accessories and jacket, collection of motion-reactive disco balls and dance performance tools, light-up mechanical flip book, and LED installations.

    alt text

    The Sparkle Stick

    How and why did you get involved in SparkFun’s Hacker-in-Residence program? Why do you think programs like this are valuable?

    I’m at SparkFun to build along side the geniuses behind the materials that have been the center of, and inspiration for, many delightful creations. I have a few beginner projects of my own I’d love to see become a kit or breakout board for others to use.

    Investing time with SparkFun’s vast offer of sensors on the body will better enable me to design wearables for everyday use that bond people without distracting them. I hope my process and project can provide valuable insight for the Sparklers (can I call them that?) to better support all of us.

    Almost every two weeks I’d been hosting a different class/workshop. SparkFun has been an amazing alley for pulling together the materials for my workshops. I continually improve the curriculum and diversify the topics I’m able to explain. Having firsthand knowledge from SparkFun and sharing what I’ve learned from teaching workshops can be instrumental in easing the learning process for others.

    What is the project you’ll be working on at SparkFun, and how long will you be here? Why did you choose this project?

    I’ll build a jacket over my three-week stay. Into this garment I’ll build a interactive system that will sense the wearer and surrounding environment.

    Spaces have a life of their own. We can expose this through realtime data collection and visualization throughout the course of an event by unleashing coordinated mobile nodes (wearables and accessories) within an environment.

    I want to use sound as a way to localize people within a space and create a platform for collaborative gaming. I’m analyzing the variety of embeddable microphones and preamps offered for use in the widest range of accessories and environments. I’ll proceed to build a system into this jacket that will react to the environment and wearer while providing data for further development of smaller pieces to coordinate the player.

    What is your superpower and snack of choice?

    Super? Thank you. Aren’t we all.

    My superpower is the ability to sleep; not in the narcoleptic sense, but I have always been a deep sleeper. I oft use a quick nap to prepare for a long night or a long night of sleep to prepare for a busy day.

    My other superpower would have to be the ability to break anything. This makes me particularity well suited to deliver a robust system because if it’ll work for me, you cannot break it.

    I hope you find your superpower(s) and use it for good.

    Snacks!?! Yes please! Do I have to pick just one? I love avocados, spinach, guacamole, Teensies, fruits, and DARK CHOCOLATE!

    Thanks Matt, we can’t wait to see how your jacket turns out!

    comments | comment feed

  • Lundi, Mars 31, 2014 - 07:00
    From the Forums – Adafruit Trellis Geome Midi Sequencer #trellis #genome #midi

    George Kuetemeyer shared an impressive Adafruit Trellis Geome Midi Sequencer on the Adafruit Forums:

    Midi music eight step sequencer demo for Adafruit Trellis keypad. Driven by Arduino Uno. Button data sent to Midi Shield. Midi data sent to Yamaha Midi sound module.

    Top six rows used for entering note data. Up to 6 notes (pentatonic scale) per step. Bottom row enables random octave shifting for given step. Second row buttons enable echo from three notes back from current step.

    Here is the code for the Geome sequencer.

    This works pretty well. Not too glitchy. Would really like to be able to handle Trellis within an interrupt handler. That way it would be easier to implement midi clock signal, etc., as I am doing with some other projects.

    Read More.

    Featured Adafruit Product!


    Adafruit Trellis Monochrome Driver PCB for 4×4 Keypad & 3mm LEDs: This item is just for the Trellis driver PCB assembly: LEDs and buttons not included. Trellis is an open source backlight keypad driver system. It is easy to use, works with any 3mm LEDs and eight tiles can be tiled together on a shared I2C bus. This PCB is specially made to match the Adafruit 4×4 elastomer keypad. Each Trellis PCB has 4×4 pads and 4×4 matching spots for 3mm LEDs. The circuitry on-board handles the background key-presses and LED lighting for the 4×4 tile. However, it does not have any microcontroller or other ‘brains’ – an Arduino (or similar microcontroller) is required to control the Trellis to read the keypress data and let it know when to light up LEDs as desired. Each tile has an I2C-controlled LED sequencer and keypad reader already on it. The chip can control all 16 LEDs individually, turning them on or off. It cannot do grayscale or dimming. The same chip also reads any keypresses made with the rubber keypad. The connections are ‘diode multiplexed’ so you do not have to worry about “ghosting” when pressing multiple keys, each key is uniquely addressed. (read more)

  • Lundi, Mars 31, 2014 - 07:00
    Using a Door Handle Conductivity to Detect Intruders

    Sometimes the simplest projects can be quite interesting, provided they’re well documented. We hope that the Hackaday readers also think that the door sensor that [Alexander] developed falls into this category. Instead of using common methods such as a magnet + reed switch, he decided to use the strike plate and door conductivity to detect someone walking in. The setup he put together includes an Arduino, a PowerSwitch Tail (a power cord that switches 120vac with a dc control voltage of 3-12vdc), a battery pack made of 8 AA batteries and two crocodile clips for door connections.

    Most new hobbyists would have stopped there, but [Alexander] checked his platform’s power consumption and continued his work to decrease it. He therefore put the microcontroller in power-down mode by default and uses an AVR external interrupt to wake it up. In case beginners can’t understand [Alexander]‘s code, he actually put a nice flow diagram on his website. Embedded after the break is a video of the system working.


    Filed under: Arduino Hacks

  • Lundi, Mars 31, 2014 - 06:00
    IRL Version of circle stop using Adafruit Neopixel ring!

    Circle stop is an addictive new game for iPhone and android. Jenny Xing decided to build an IRL version using one of our neopixel rings- very cool!

    A team here at @pearlhacks built a real version of #circlestop!

    Read more.

    Featured Adafruit Product!


    NeoPixel Ring – 12 x WS2812 5050 RGB LED with Integrated Drivers: Round and round and round they go! 12 ultra bright smart LED NeoPixels are arranged in a circle with 1.5″ (37mm) outer diameter. The rings are ‘chainable’ – connect the output pin of one to the input pin of another. Use only one microcontroller pin to control as many as you can chain together! Each LED is addressable as the driver chip is inside the LED. Each one has ~18mA constant current drive so the color will be very consistent even if the voltage varies, and no external choke resistors are required making the design slim. Power the whole thing with 5VDC and you’re ready to rock. Read more.

  • Lundi, Mars 31, 2014 - 04:00
    Controlling The Garmin HUD With Bluetooth


    The Garmin HUD is a very neat device, putting all your navigational info, from ETA, what lane you should be in, and distance to your next turn right on your windscreen in a heads-up display. The only problem with the Garmin HUD is that it only works with the official Garmin app, despite being a Bluetooth device. Now, someone is finally digging in to the Garmin HUD protocol, allowing anyone to control this HUD from a cell phone, tablet, or computer.

    Being completely unable to disassemble the Navigon app for the HUD, [gabonator] decided the only thing to do would be to open up the device and take a peek at some of the packets travelling between the microcontroller and bluetooth module.

    [gabonator] expected human readable ASCII characters, but after looking at the nonsense decoded from his oscilloscope and decoding them manually, he tried simply looking at the display in operation to understand how the protocol worked. He got it all decoded, and managed to get a Sygic Navigation program working with this Garmin HUD. You can check out a video of that below.

    Thanks [Kevin] for the tip.

    Filed under: transportation hacks

  • Lundi, Mars 31, 2014 - 01:01
    Hackaday Links: March 31, 2014


    Wanting to display his Google calendars [Chris Champion] decided to mount an old monitor on the wall. The hack is his installation method which recesses both the bracket and the outlet while still following electrical code (we think).

    Since we’re already on the topic. Here’s a hack-tacular project which hangs a laptop LCD as if it were a picture frame. We do really enjoy seeing the wire, which connects to the top corners and hangs from a single hook a few inches above the screen bezel. There’s something very “whatever works” about it that pleases us.

    [Jaspreet] build a datalogger in an FPGA. He put together a short video demo of the project but you can find a bit more info from his repo. He’s using a DE0-Nano board which is a relatively low-cost dev board from Terasic.

    Want to see what’s under the hood in the processor running a Nintendo 3DS? Who wouldn’t? [Markus] didn’t just post the die images taken through his microscope. He documented the entire disassembly and decapping process. Maybe we should have given this one its own feature?

    If you’re streaming on your Ouya you definitely want a clean WiFi signal. [Michael Thompson] managed to improve his reception by adding an external antenna.

    We always like to hear about the free exchange of information, especially when it comes to high-quality educational material. [Capt Todd Branchflower] teaches at the United States Air Force Academy. He wrote in to say that his ECE383 Embedded Systems II class is now available online. All the info can also be found at his Github repo.

    And finally, do you remember all the noise that was made about 3D printed guns a while back? Well [Mikeasaurus] put together the .iStab. It’s a 3D printed iPhone case with an integrated folding blade…. for personal protection? Who knows. We think it should be a multitasking solution that functions as a fold-down antenna.

    Filed under: Hackaday Columns, Hackaday links

  • Dimanche, Mars 30, 2014 - 23:23
    HARDWARE HANGOUT with Brady Forrest Tuesday 7pm ET 4/1/14 #makerbusiness @brady @highway1io @PCH_Intl #Hardware #startup #incubator

    Adafruit 2257-2
    Logo - With Pch
    Come meet and ask questions on our next HARDWARE HANGOUT with Brady Forrest. Brady runs Highway1 and helps shepherd startups of all backgrounds into their Accelerator program. He also co-founded Ignite – a geek event which has spread to over a hundred cities worldwide.. PCH is a large supply chain management company with primary operations in Shenzhen. It ships $10B of product annually. Highway1 helps you get your prototype ready for market. Based in SF, they are a four month program & currently hosting 11 companies – primarily consumer. The next class runs Mar-Jun. More about Brady – he is Vice President at Highway1, PCH International’s incubator program. A prolific speaker and maker on the geek scene, Brady can be found at speaking engagements around the world, inventing new forms of transportation at Burning Man, or creating in the Highway1 San Francisco workshop. Additionally, Brady writes for O’Reilly Radar, tracking changes in technology.

    Things we’ll be asking!

    • When/if makers should crowdfund?
    • When do you hire certain roles?
    • What are the hidden gotchas?
    • When/should you go to China?
    • How?
    • The role of opensource

    Post your questions here, on G+, join live and more!. Click here for the Google+ Hangout page (you can start asking your questions now too).

  • Dimanche, Mars 30, 2014 - 22:00
    Measuring Magnetic Fields with a Robotic Arm


    Learning how magnets and magnetic fields work is one thing, but actually being able to measure and see a magnetic field is another thing entirely! [Stanley's] latest project uses a magnetometer attached to a robotic arm with 3 degrees of freedom to measure magnetic fields.

    Using servos and aluminium mounting hardware purchased from eBay, [Stanley] build a simple robot arm. He then hooked an HMC5883L magnetometer to the robotic arm. [Stanley] used an Atmega32u4 and the LUFA USB library to interface with this sensor since it has a high data rate. For those of you unfamiliar with LUFA, it is a Lightweight USB Framework for AVRs (formerly known as MyUSB). The results were plotted in MATLAB (Octave is free MATLAB alternative), a very powerful mathematical based scripting language. The plots almost perfectly match the field patterns learned in introductory classes on magnetism. Be sure to watching the robot arm take the measurements in the video after the break, it is very cool!

    [Stanley] has graciously provided both the AVR code and the MATLAB script for his project at the end of his write-up. It would be very cool to see what other sensors could be used in this fashion! What other natural phenomena would be interesting to map in three dimensions?

    Filed under: robots hacks

  • Dimanche, Mars 30, 2014 - 21:29
    New Project: Controlling a lock with an Arudino and Bluetooth LE

    BluetoothLock_EnterCodeThis project allows you to open a solenoid lock from a PhoneGap app using the Bluetooth Serial Plugin and the new Adafruit Bluetooth LE break-out board for the Nordic Semiconductor nRF8001 chip.

    Read more on MAKE

  • Dimanche, Mars 30, 2014 - 21:29
    New Project: Controlling a lock with an Arduino and Bluetooth LE

    BluetoothLock_EnterCodeThis project allows you to open a solenoid lock from a PhoneGap app using the Bluetooth Serial Plugin and the new Adafruit Bluetooth LE break-out board for the Nordic Semiconductor nRF8001 chip.

    Read more on MAKE

  • Dimanche, Mars 30, 2014 - 19:00
    Reflowing With A Hair Straightener


    Around here, reflow ovens usually mean a toaster oven, and if you’re exceptionally cool, a thermistor and PID controller. There are, of course, a thousand ways to turn solder paste into a solid connection and [Saar] might have found the cheapest way yet: a hair straightener with a street value of just £15.

    We don’t expect the majority of the Hackaday demographic to know much about hair straighteners, but [Saar] has done all the work and came up with a list of what makes a good one. Floating plates are a must to keep the PCB in contact with the heating element at all times, and temperature control is essential. [Saar] ended up with a Remington S3500 Ceramic Straight 230 Hair Straightener, although a trip to any big box store should yield a straightener that would work just as well.

    One modification [Saar] added was a strip of Kapton tape to one of the ceramic heating elements. It’s not a replacement for a toaster oven or real reflow oven, but for small boards it works just as well.

    Video below.

    Filed under: tool hacks

  • Dimanche, Mars 30, 2014 - 17:22
    Brighten Your Smile with Weekend Projects and the Toothy Toothbrush Timer

    wp02_ttt_gif1Watch how to modify novelty chattering teeth and turn a servomotor into a regular gearmotor for the Toothy Toothbrush Timer, a two-minute timer for your tooth-brushing routine.

    Read more on MAKE

  • Dimanche, Mars 30, 2014 - 16:00
    LEGO® My Single-Phase Induction Motor

    [Diato556] made a really cool single-phase induction motor with parts mounted on Duplo blocks. He has posted an Instructable where he uses these modular parts to  demonstrate the motor and the principles of induction as described after the jump.



    [Diato556] starts with an AC generator, a tiny alternator made with the coil from a relay and the magnet from a bicycle dynamo. He rotates the magnet on a spit in front of the relay coil, producing an induced current that lights an LED connected to the relay.


    Rotating magnetic field

    Next up is a rotating magnetic field demonstration. Using the same rotisserie magnet, he induces a current in a rotor made from a small aluminium cylinder. The cylinder pivots against a nail and induced current causes the rotor to spin.


    Induction motor

    The induction motor builds from previous experiment. Instead of the magnet, the two coils induce current in the rotor. One is fed directly from 12VAC, and the other coil’s power is delayed with a 4.7μF capacitor. The alternating magnetic field causes the rotor to spin.


    This is a neat project on so many levels. The modular Duplo-entrenched parts are just plain cool. Give demonstrations at the office, or just keep it around as a fun desk toy or conversation piece. If you don’t have a desk and must carry your conversation pieces on your person, you can’t go wrong with this induction flashlight.


    Filed under: how-to, parts

  • Dimanche, Mars 30, 2014 - 13:00
    DIY Bluetooth Boombox Can Take a Beating!


    Looking for a nice portable audio solution that can take a beating outdoors? This RaveBOX (v1.0) might be what you’re looking for!

    [Angelo] is a 15 year old high school student from the Philippines who loves making things — in fact, he has a collection over 40 Instructables that he’s written himself to share with the world. He wrote his first when he was only 10 years old.

    He was inspired to build this boombox when he stumbled upon a Pelican-like rugged case at the mall, so he bought it and started planning the build around it. He’s using a pair of 2-channel audio amplifiers hooked up to a Bluetooth/FM/USB/SD card player module which has a nice face-plate for external mounting. It drives a 4″ woofer, and 4 full range speakers. To modify the case, he used a Dremel and pocket knife, and we must say, he did a great job! The 12V 2.2aH lithium polymer battery provides a surprising 18 hours of playback.

    It’s a great beginner’s project to get into soldering — nothing too complex, but the resulting boombox is quite useful — and [Angelo's] got a great guide to get you started!

    If you’re looking for a bit more stylish boombox, why not build one out of a briefcase?

    Filed under: digital audio hacks

  • Dimanche, Mars 30, 2014 - 10:00
    Malware In A Mouse


    Keyloggers, in both hardware and software forms, have been around for a long, long time. More devious keyloggers are smart enough to ‘type’ commands into a computer and install Trojans, back doors, and other really nasty stuff. What about mice, though? Surely there’s no way the humble USB mouse could become an avenue of attack for some crazy security shenanigans, right?

    As it turns out, yes, breaking into a computer with nothing but a USB mouse is possible. The folks over at CT Magazine, the preeminent German computer rag, have made the Trojan mouse (German, terrible Google translation)

    The only input a mouse receives are button presses, scroll wheel ticks, and the view from a tiny, crappy camera embedded in the base. The build reads this camera with an Arduino, and when a certain pattern of gray and grayer pixels appear, it triggers a command to download a file from the Internet. From there, and from a security standpoint, Bob’s your uncle.

    Looking through the camera inside a mouse is nothing new; it’s been done over the Internet and turned into the worst scanner ever made. Still, being able to process that image data and do something with it is very cool. Just don’t accept mouse pads from strangers.

    Danke [Ianmcmill] for the tip.

    Filed under: peripherals hacks, security hacks

  • Dimanche, Mars 30, 2014 - 09:00
    14-year-old can save the government millions by changing font style

    14-year-old Suvir Mirchandani’s science fair project was to determine how his middle school could reduce ink usage to cut waste and cost. What he found would save his school thousands of dollars, and, if applied to the federal and state governments, millions!

    “Ink is two times more expensive than French perfume by volume,” Suvir says with a chuckle.

    He’s right: Chanel No. 5 perfume costs $38 per ounce, while the equivalent amount of Hewlett-Packard printer ink can cost up to $75.

    So Suvir decided to focus his project on finding ways to cut down on the costly liquid.
    Collecting random samples of teachers’ handouts, Suvir concentrated on the most commonly used characters (e, t, a, o and r).

    First, he charted how often each character was used in four different typefaces: Garamond, Times New Roman, Century Gothic and Comic Sans. Then he measured how much ink was used for each letter, using a commercial tool called APFill® Ink Coverage Software.

    Next he enlarged the letters, printed them and cut them out on cardstock paper to weigh them to verify his findings. He did three trials for each letter, graphing the ink usage for each font.
    From this analysis, Suvir figured out that by using Garamond with its thinner strokes, his school district could reduce its ink consumption by 24%, and in turn save as much as $21,000 annually.

    With encouragement from his teacher and the founders of the Journal for Emerging Investigaors, Suvir applied his research to a larger institution, the government.

    Using the General Services Administration’s estimated annual cost of ink — $467 million — Suvir concluded that if the federal government used Garamond exclusively it could save nearly 30% — or $136 million per year. An additional $234 million could be saved annually if state governments also jumped on board, he reported.

    Read more.

  • Dimanche, Mars 30, 2014 - 08:00
    Using Minecraft to Understand the Speed of Light

    YouTube user spumwack explains and demonstrates the speed of light using Minecraft. Don’t blink! You don’t want to miss it. via digg

  • Dimanche, Mars 30, 2014 - 07:00
    Scientists Create Biodegradable Battery That ‘Melts’ Inside The Body After Use


    An exciting new biodegradable battery unveiled by a team of scientists could have huge potential for biomedical devices. The tiny battery can be safely absorbed by the body within just three weeks and could be used in temporary devices intended to monitor tissue or deliver short term treatment. From Nature:

    Their devices, described last week in Advanced Materials, use anodes of magnesium foil and cathodes of iron, molybdenum or tungsten. All these metals will slowly dissolve in the body, and their ions are biocompatible in low concentrations. The electrolyte between the two electrodes is a phosphate-buffered saline solution, and the whole system is packed up in a biodegradable polymer known as a polyanhydride.

    Currents and voltages vary depending on the metal used in the cathode. A one-square-centimetre cell with a 50-micrometre-thick magnesium anode and an 8-micrometre-thick molybdenum cathode produces a steady 2.4 milliamps of current, for example. Once dissolved, the battery releases less than 9 milligrams of magnesium — roughly twice as much as a magnesium coronary artery stent that has been successfully tested in clinical trials, and a concentration that is unlikely to cause problems in the body, says Rogers. “Almost all of the key building blocks are now available” to produce self-powered, biodegradable implants, he says.

    All versions can maintain a steady output for more than a day, but not much longer. The team hopes to improve the batteries’ power per unit weight — known as power density — by patterning the surface of the magnesium foil to increase its surface area, which should enhance its reactivity. The authors estimate that a battery measuring 0.25 cm2 and just one micrometre thick could realistically power a wireless implantable sensor for a day.

    Read more.