Clippings

Virus-Assembled Microbatteries

Link: Technology Review: Virus-Assembled Microbatteries.

"As electronic devices are made ever smaller, there is increasing demand for similarly minuscule power sources. Now MIT researchers have reported an important advance toward building such microscopic batteries. They used a virus to assemble anodes on top of electrolyte layers--two of the three main components of a working battery.

[Prof. Angela Belcher] adds that the cobalt oxide anode has a much higher charge storage capacity than the carbon-based electrodes typically used in lithium-ion batteries, and that it's stable throughout charging and discharging. It also has a higher density of active material than do conventional batteries.

Other advantages of virus assembly include functioning at room temperature and precise control over the size and spacing of nanomaterials, leading to uniform and easily reproducible devices."

The process involves etching micrometer-wide columns into silicon, laying down alternating layers of two polymers, then using the virus M13 to lay down "structured arrays of cobalt oxide nanowires" (previous described in Virus-Built Electronics) .  The next step is to self-assemble cathodes, the remaining element of the battery. 

The batteries could be used in "labs on a chip" or miniature medical devices.

Smart future for swarming robots

Link: BBC NEWS | Technology | Smart future for swarming robots.

"For a long time in robotics there was this focus on a 'smart machine', an android that would make you breakfast and go out and buy your shopping," said Dr Seth Bullock, the University of Southampton researcher chairing the Alife XI conference.

"But that's extremely challenging; it's going to be far easier for us to engineer little simple things and rely on them to organise themselves."

University of Southampton undergraduate students have developed robots the size of matchboxes and costing £24 each.  They demonstrate that "how swarm robots can independently divide up tasks, with no central program controlling them."  The swarm  showed flexibility in being able to handle losing a number of members 

The Sbot robots developed b the Free University of Brussels and the Institute for Cognitive Science and Technology were able to form chains of up to 20 robots and handle unpredicted events. 

Applications include working in space, searching in collapsed buildings or building large renewable energy farms.

 

Root mechanics tip balance of power

Link: Root mechanics tip balance of power.

"An ingenious device – inspired by growing plant root tips – is opening up a new type of hydraulic fluid power.  Hydraulic actuators – which are powered by osmosis and inspired by growing plant root tips – are able to deliver very large forces at low power.

Because they act very slowly, they could never replace conventional hydraulic applications such as earth moving equipment. But potential applications include: an alternative way to break up rocks or concrete – offering potential in the mining or construction industries; and as a way of keeping steel ropes in tension – such as on a suspension bridge."

Osmosis, a driving force behind root tips, involves movement of water molecules through a membrane separating two solutions of differing concentrations.  Barbara Mazzolai (Scuola Superiore Sant'Anna, Pisa) has developed a way to make the process reversible using an electric charge and anion exchange members.   Pressures of 0.3 to 0.5Mpa (3 to 5 bar) have been created, although osmotic pressures 10 times more powerful are seen in nature. 

A prototype that can force its way through soil and steer itself has been built.  Although slow, the system appears to be very efficient and is also inexpensive.

Thanks to Jo Lakeland and BIONIS for the pointer!

Inspired by nature | Popular Science

Link: Inspired by nature | Popular Science.

Popular Science has six articles in this series:

• Yeast, What is it Good For? (Absolutely Something) (similar metabolic mechanism and fast reproduction can help screen drugs or test gene expression)
• For Treating Blindness, Scientists Look to Algae (protein extracted from Chlamydomonas may help in increasing light sensitivity in certain forms of blindness)
• The Science of Swine (swine cells have helped regenerate severed fingers and may provide a cure for diabetes; urea can be used as a raw material for plastics)
• Bacteria to the Rescue (genetically modified bacteria may fight cancer, reduce damage from radiation treatments, produce ethanol or remediate soils)
• Gecko Tech (dry adhesion, Tail 'key' for gecko acrobatics)
• The Hidden Talents of the Lowly Sea Cucumber (Copying Sea Cucumber's Cool Trick to develop plastics with controlled rigidity, controlling malaria parasite, artificial corneas and tendons)

Most of the stories are about bio-utilization, although some involve a deeper understanding of the principles behind how nature solves problems.

Thanks to Manfred Drack for the pointer!
 

'Major Discovery' Primed To Unleash Solar Revolution: Scientists Mimic Essence Of Plants' Energy Storage System

Link: 'Major Discovery' Primed To Unleash Solar Revolution: Scientists Mimic Essence Of Plants' Energy Storage System.

"Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today's announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy."

This article and numerous others such as Solar-Power Breakthrough describe the work of Prof. Daniel Nocera of MIT to develop an inexpensive catalyst that generates oxygen from water at room temperature and a neutral pH.  The catalyst is amorphous and relatively unstable, but can constantly repair itself.  When combined with an catalyst such as platinum which produces hydrogen, water can be split into its components which can then be stored and later used in a fuel cell to generate electricity or burned to produce heat or motion. 

A number of the articles emphasize that this discovery was inspired by photosynthesis, without explaining the connection.  At present, plants still have an edge in terms of integrated the capture of solar energy, the transformation into stable compounds and the ability to use that stored energy at will.  Although Nocera's discovery shows great promise, it is only a part of the system.  At present, an external electricity source is required, although research is underway to generate electricity internally so that the reaction can be run using just sunlight.  Hydrogen is also difficult to store and transport, due to its small molecular size. Finally, the technology appears to have little connection with photosynthesis, at least compared to Monash team learns from nature to split water.

Thanks to Ian Abbott-Donnelly and Jean-Francois Barsoum for the pointers!

New 'super-paper' is stronger than cast iron - tech - 06 June 2008 - New Scientist Tech

Link: New 'super-paper' is stronger than cast iron - tech - 06 June 2008 - New Scientist Tech.

"Cellulose nanofibres are the main reinforcement in all plant structures and are characterised by nanoscale dimensions, high strength and toughness," Berglund told New Scientist.

Cellulose is extracted from wood to make paper, is the basis of cellophane, and has also recently been used by materials scientists developing novel plastic materials. But they have used it only as a cheap filler material, ignoring its mechanical properties. ... Berglund and colleagues have developed a gentler process that preserves the fibres' strength.

Regular has a tensile strength of around 1 megapascals, due to the damage done to the cellulose during pulping of the wood.  Berglund's process retains the structure of the fibers and their ability to form networks through hydrogen bonding.  Paper produced by this process has a tensile strength of 214 MPa, exceeding cast iron at 130 MPa and close to that of structural steel at 250 MPa.  The fibers are much finer than those in regular paper, reducing the size of any defects.   Although strongly bonded, the ability of the fibers to slip increases resilience to stress.

Monash team learns from nature to split water

Link: Monash team learns from nature to split water.

An international team of researchers led by Monash University has used chemicals found in plants to replicate a key process in photosynthesis paving the way to a new approach that uses sunlight to split water into hydrogen and oxygen. ...

"We have copied nature, taking the elements and mechanisms found in plant life that have evolved over 3 billion years and recreated one of those processes in the laboratory," Professor Spiccia said."

Professor Leone Spiccia, Mr Robin Brimblecombe and Dr Annette Koo from
Monash University teamed with Dr Gerhard Swiegers at the CSIRO and
Professor Charles Dismukes at Princeton University impregnated a proton conductor (Nafion) with manganese clusters.  The catalyst was able to split water into oxygen and hydrogen when the Nafion membrane was exposed to sunlight along with a 1.2 volt electrical potential. The paper is published in the August 1st edition of Angewandte Chemie International Edition (subscription required)

In plants, manganese clusters are a critical part of photosynthesis, where sunlight converts water and carbon dioxide into oxygen and carbohydrates.  Although the reaction is driven to some extent by sunlight, plants still have the advantage of requiring no electricity and producing an end-product that can be easily stored for periods when the sun does not shine.  One of the challenges of the 'hydrogen economy' is managing hydrogen, a notoriously hard-to-handle gas.

Bat adopts insect flight trick

Link: BBC NEWS | Science/Nature | Bat adopts insect flight trick.

"Bats use the same aerodynamic mechanism as insects to hover in one place, scientists have found.

Writing in Science, they said that as the animal flapped its wings downwards, the motion created a tiny cyclone of air known as a "leading edge vortex".

This provided enough lift force to keep the bat airborne while hovering or flying in slow motion."

A team of Swedish and US researchers led by Anders Hedenstrom (Lund University) have shown that 'leading edge vortices' (LEVs) "provide as much as 40% of the lift force that helped the bats stay aloft" when bats are hovering or flying slowly.  LEVs are common in insect flight but have not been observed in larger animals.

Insects produce similar LEVs by flapping their wings quickly, whereas bats rely on their ability to control the shape of their wings.  The principles could be applied to micro air vehicles (MAVs).

Tail 'key' for gecko acrobatics

Link: BBC NEWS | Science/Nature | Tail 'key' for gecko acrobatics.

"A gecko's tail is as crucial to the animal's acrobatic ability as its "sticky" feet, scientists report.

High-speed video reveals that the creature uses its tail as a "fifth leg" to prevent it from slipping as it climbs wet surfaces.

And the footage shows that if it does fall, a flick of the tail is all it takes for the gecko to land feet-down."

"The researchers from the University of California, Berkeley, said the discovery could aid the development of improved climbing robots and unmanned gliding vehicles"

Researchers lead by Prof. Robert Full of Berkeley's Center for Interdisciplinary Bio-inspiration in Education and Research employed high-speed video to understand how geckos use their tails to stabilize themselves when they lose their footing on slippery surfaces.  Geckos can also use their tails to right themselves during a fall and even maneuver to "allow the animal to direct its aerial descent to land on a perch rather than hitting the ground if it fell out of the rainforest canopy".

Although much of the research on geckos has focused on how their feet help them stick to surfaces, this study shows the value of looking at 'the entire package' for synergy between various adaptations.

Device 'spins silk like spiders'

Link: BBC NEWS | Science/Nature | Device 'spins silk like spiders'.

"A device that partially mimics the process by which spiders produce fine, yet super-strong, silks has been built."

"We can observe the initial steps of fibre formation, which was not possible before," explained Sebastian Rammensee of the Technical University of Munich and one of the authors of the Proceedings of the National Academy of Science's paper.

"Now we can better understand how the processing conditions affect the quality of the silk."

Researchers created a device with three channels etched in glass that combined salt solutions with a spider silk proteins from genetically-engineered bacteria.  Different  fiber grades could be extruded by varying the protein and salts. 

The article goes on to describe the challenges of creating artificial spider silk of a quality equivalent to the natural fiber - maintaining chemical purity and exacting environmental conditions makes the process very expensive.  Instead, Oxford Biomaterials is harvesting natural silks from an unidentified species for medical applications.