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Artificial ‘cricket hair’ sensors from the Dutch

Friday, June 7th, 2013

What do you do when the very phenomenon you’re trying to sense (low frequency signals) frustrates your efforts? Scientists at the University of Twente’s MESA+ Institute for Nanotechnology responded by moving the signals into the frequency range for the sensors, which are modeled on cricket hairs. From the June 6, 2013 news item on Nanowerk (Note: A link has been removed),

An “artificial cricket hair” used as a sensitive flow sensor has difficulty detecting weak, low-frequency signals – they tend to be drowned out by noise. But now, a bit of clever tinkering with the flexibility of the tiny hair’s supports has made it possible to boost the signal-to-noise ratio by a factor of 25. This in turn means that weak flows can now be measured. Researchers at the MESA+ Institute for Nanotechnology of the University of Twente (NL) have presented details of this technology in the New Journal of Physics (“Uncovering signals from measurement noise by electro mechanical amplitude modulation”).

The University of Twente June 6, 2013 news release, which originated the news item, describes how  biomimicry (copying cricket hairs) combined with technology in old AM radios were combined to solve the problem,

These tiny hairs, which are manufactured using microtechnology techniques, are neatly arranged in rows and mimic the extremely sensitive body hairs that crickets use to detect predators. When a hair moves, the electrical capacitance at its base changes, making the movement measurable. If there is an entire array of hairs, then this effect can be used to measure flow patterns. In the same way, changes in air flow tell crickets that they are about to be attacked.

Tiny “hairs” of the polymer SU-8 are applied to a flexible, moving surface, the capacitance of which changes with each movement.

Mechanical AM radio

In the case of low-frequency signals, the noise inherent to the measurement system itself tends to throw a spanner in the works by drowning out the very signals that the system was designed to measure. One very appealing idea is to “move” these signals into the high frequency range, where noise is a much less significant factor. The MESA+ researchers achieve this by periodically changing the hairs’ spring rate. They do so by applying an electrical voltage.

The original signal (top), the signal at a sensor vibrating at a higher frequency (centre), and the reconstructed signal (bottom)

This adjustment also causes the hairs to vibrate at a high frequency. This resembles the technology used in old AM radios, where the music signal is encoded on a higher frequency wave. In the case of the sensor, its “radio” is a mechanical device. Low frequency flows are measured by tiny hairs vibrating at a higher frequency. The signal can then be retrieved, with significantly less noise. Suddenly, a previously unmeasurable signal emerges, thanks to this “up-conversion”.

This electromechanical amplitude modulation (EMAM) expands the hair sensors’ range of applications enormously. Now that the signal-to-noise ratio has been improved by a factor of 25, it is possible to measure much weaker signals. According to the researchers, this technology could be a very useful way of boosting the performance of many other types of sensors.

You can find out more about the paper here,

The article by Harmen Droogendijk, Remco Sanders and Gijs Krijnen, entitled “Uncovering signals from measurement noise by electromechanical amplitude modulation” has been published in the New Journal of Physics, an open-access journal.

After reading about this research I got a little curious about crickets and found an online set of instructions for drawing them. From the How to Draw a Cricket webpage on the DragonArt.com website, here’s step 6,

STEP 6. This is what your cricket should end up looking like this. Color him/her in and you have just finished this lesson on "how to draw a cricket insect step by step". Credit: Dawn

STEP 6.
This is what your cricket should end up looking like this. Color him/her in and you have just finished this lesson on “how to draw a cricket insect step by step”. Credit: Dawn

Thanks to Dawn for uploading her cricket (insect) drawing instructions.

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Cambridge University wants to take its flexible opals to market

Thursday, May 30th, 2013

Structural colour due to nanoscale structures such as those found on Morpho butterfly wings, jewel beetles, opals, and elsewhere is fascinating to me (Feb. 7, 2013 posting). It would seem many scientists share my fascination  including these groups at the UK’s University of Cambridge and Germany’s Fraunhofer Institute, from the May 30, 2013 University of Cambridge news release (also on EurekAlert),

Instead of through pigments, these ‘polymer opals’ get their colour from their internal structure alone, resulting in pure colour which does not run or fade. The materials could be used to replace the toxic dyes used in the textile industry, or as a security application, making banknotes harder to forge. Additionally, the thin, flexible material changes colour when force is exerted on it, which could have potential use in sensing applications by indicating the amount of strain placed on the material.

The most intense colours in nature – such as those in butterfly wings, peacock feathers and opals – result from structural colour. While most of nature gets its colour through pigments, items displaying structural colour reflect light very strongly at certain wavelengths, resulting in colours which do not fade over time.

In collaboration with the DKI (now Fraunhofer Institute for Structural Durability and System Reliability) in Germany, researchers from the University of Cambridge have developed a synthetic material which has the same intensity of colour as a hard opal, but in a thin, flexible film.

Here’s what the researchers’ synthetic opal looks like,

Polymer Opals Credit: Nick Saffel [downloaded from http://www.cam.ac.uk/research/news/flexible-opals]

Polymer Opals Credit: Nick Saffel [downloaded from http://www.cam.ac.uk/research/news/flexible-opals]

The news release provides a brief description of naturally occurring opals and contrasts them with the researchers’ polymer opals,

Naturally-occurring opals are formed of silica spheres suspended in water. As the water evaporates, the spheres settle into layers, resulting in a hard, shiny stone. The polymer opals are formed using a similar principle, but instead of silica, they are constructed of spherical nanoparticles bonded to a rubber-like outer shell. When the nanoparticles are bent around a curve, they are pushed into the correct position to make structural colour possible. The shell material forms an elastic matrix and the hard spheres become ordered into a durable, impact-resistant photonic crystal.

“Unlike natural opals, which appear multi-coloured as a result of silica spheres not settling in identical layers, the polymer opals consist of one preferred layer structure and so have a uniform colour,” said Professor Jeremy Baumberg of the Nanophotonics Group at the University’s Cavendish Laboratory, who is leading the development of the material.

Like natural opals, the internal structure of polymer opals causes diffraction of light, resulting in strong structural colour. The exact colour of the material is determined by the size of the spheres. And since the material has a rubbery consistency, when it is twisted and stretched, the spacing between spheres changes, changing the colour of the material. When stretched, the material shifts into the blue range of the spectrum, and when compressed, the colour shifts towards red. When released, the material will return to its original colour.

I find the potential for use in the textile industry a little more interesting than the anti-counterfeiting application. (There’s a Canadian company, Nanotech Security Corp., a spinoff from Simon Fraser University, which capitalizes on the Blue Morpho butterfly wing’s nanoscale structures for an anti-counterfeiting application as per my first posting about the company on Jan. 17, 2011.) There has been at least one other attempt to create a textile that exploits structural colour. Unfortunately Teijin Fibres has stopped production of its morphotex, as per my April 12, 2012 posting.

Here’s what the news release has to say about textiles and the potential importance of structural colour,

The technology could also have important uses in the textile industry. “The World Bank estimates that between 17 and 20 per cent of industrial waste water comes from the textile industry, which uses highly toxic chemicals to produce colour,” said Professor Baumberg. “So other avenues to make colour is something worth exploring.” The polymer opals can be bonded to a polyurethane layer and then onto any fabric. The material can be cut, laminated, welded, stitched, etched, embossed and perforated.

The researchers have recently developed a new method of constructing the material, which offers localised control and potentially different colours in the same material by creating the structure only over defined areas. In the new work, electric fields in a print head are used to line the nanoparticles up forming the opal, and are fixed in position with UV light. The researchers have shown that different colours can be printed from a single ink by changing this electric field strength to change the lattice spacing.

As for wanting to take this research to market, from the news release,

Cambridge Enterprise, the University’s commercialisation arm, is currently looking for a manufacturing partner to further develop the technology and take polymer opal films to market.

For more information, please contact sarah.collins@admin.cam.ac.uk.

The reference to opals reminded me of yet another Canadian company exploring the uses of structural colour, Opalux, as per my Jan. 31, 2011 posting.

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Shapeshifting, paradigm shifting nanoparticles

Wednesday, May 29th, 2013

Scientists at the University of California at San Diego (UCSD) had approached the problem of targeting diseased cells in a new way, according to the May 28, 2013 UCSD news release (also available on EurekAlert) by Susan Brown,

Targeting treatments specifically to cancerous or other diseased cells depends on some means of accumulating high levels of a drug or other therapeutic agent at the specific site and keeping it there. Most efforts so far depend on matching a piece of the drug-delivering molecule to specific receptors on the surface of the target cell.

Inspiration for this new strategy came from biological systems that use shape to alter the ability of something to lock in place or slip away and escape, said Nathan Gianneschi, a professor of chemistry and biochemistry, who led the project.

“We wanted to come up with a new approach,” Gianneschi said. “Specifically, we wanted to design switchable materials that we could inject in one shape and have them change to another between the blood and tumors.”

Here’s how they did it,

Some cancerous tissues produce high levels of a class of molecules called MMPs, for matrix metalloproteinases. These enzymes change how other proteins behave by altering their molecular configuration, leading to metastasis. Gianneschi and colleagues harnessed this ability to alter their nanoparticles in ways that would cause them to linger at the site of the tumor.

“We figured out how to make an autonomous material that could sense its environment and change accordingly,” Gianneschi said.

Each nanoparticle is made of many detergent-like molecules with one end that mixes readily with water and another that repels it. In solution, they self assemble into balls with the water-repellant ends inside, and in that configuration can easily be injected into a vein.

When mixed with MMPs in vials, the enzymes nicked the peptides on the surface of the spheres, which reassembled into netlike threads.

The team tested the concept further by injecting their new nanoparticles into mice with human fibrosarcomas, a kind of cancer that produces high levels of MMPs.

To mark when the spheres broke down to form other structures, the chemists placed one of two fluorecent dyes, rhodamine or fluorescein, inside the spheres. In close proximity, the dyes interact to create a specific light signal called FRET for Förster Resonance Energy Transfer, when energy jumps from rhodamine to fluorescein.

Within a day they detected FRET signals indicating that the spheres had reassembled at the sites of the tumors, and the signal persisted for at least a week.

The treatment is not inherently toxic. [emphasis mine] It did not appear to change the tumors in any way, and liver and kidney, the organs most vulnerable to collateral damage from treatments because they clear toxins from the body, were normal and healthy eight days after injection.

Different versions of these nanoparticles could be designed to respond to signals inherent to other types of cancers and inflamed tissue, the authors say. The spheres can also be engineered to carry drugs, or different diagnostic probes.

Right now, this same team is developing nanoparticles that carry an infrared dye, which would enable them to visualize tumors deeper inside the body along with other materials that can be imaged with instruments commonly available in the clinic.

I’m not sure I’d call this a ‘treatment’, it seems more like a new technique for drug delivery, diagnosis, etc. That quibble aside, this sounds very exciting and I hope the researchers will be able to start human clinical trials in the near future.

For those who’d like to read the research,

Enzyme-Directed Assembly of a Nanoparticle Probe in Tumor Tissue by Miao-Ping Chien, Matthew P. Thompson, Christopher V. Barback, David J. Hall, and Nathan C. Gianneschi.
ADVANCED MATERIALS, 2013, DOI: 10.1002/adma.201300823

This paper is behind a paywall.

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Spider-mites spin new nanomaterial at Canada’s University of Western Ontario

Thursday, May 23rd, 2013

I’m not always the sharpest knife in the drawer and skimming news articles exacerbates the problem, so, it took me a minute (more or less) to realize that spiders and spider-mites are not the same, which is what makes this discovery about spider-mite silk, featured in a May 23, 2013 news item on phys.org, special in amongst the many stories on spider silk (Note: A link has been removed),

A new, natural nanomaterial, which may prove incredibly beneficial to medical bioengineers, has been discovered by the research team at Western University [aka University of Western Ontario] that successfully sequenced the spider mite genome in 2011.

Western biology professor Miodrag Grbic and his team have now collaborated with physicist Jeff Hutter to test – for the first-time ever – the durability of spider-mite silk and found the bionanomaterial, which is one thousand times thinner than human hair, to be a potentially superior alternative to spider silk, itself long considered a highly attractive light-weight biomaterial due to its high tensile strength and elasticity.

This is a very good video from Western University (aka University of Western Ontario) featuring both Grbić and Hutter describing their work,

The Western University Apr. 25, 2013 media release, which originated the news item on phys.org, echoes the content in the video,

“One of the discoveries spinning out from our sequencing of the spider-mite genome was spider-mite silk,” explains Grbic, regarding the findings published in Nature in 2011. “When we conceived this project, our idea was to develop tools to control this important world-wide pest but we didn’t even dream that we were going to discover a potential bionanomaterial naturally produced by the spider-mite.”

Due to the near infinitesimal size of the spider mite silk, traditional theories were irrelevant so Hutter and Steve Hudson from the Department of Physics & Astronomy were forced to rethink conventional methods used for measuring the mechanical properties of nanomaterials.

“Basically you measure the strength of a nanofibre by anchoring it at both ends, suspending it, and then bending it with an atomic force microscope,” explains Hutter. “These fibres were so thin that the conventional theory didn’t apply and we had to develop a new theory to understand the data.”

Hutter and Grbic are most excited that spider mite silk has proven to be a truly natural nanomaterial, making its practical applications numerous.

“Spider silk, which people often talk about, has similar properties but it doesn’t score quite as high on Young’s modulus,” says Hutter, explaining the scientific measure used to characterize stiffness in elastic materials. “Plus spider mite silk is way thinner.”

Grbic says potential applications would require further research but could include construction of scaffolding for cell growth, as well as tissue regeneration and transplantation.

Here’s a link to and citation for the team’s latest spider mite silk paper,

Measurement of the elastic modulus of spider mite silk fibers using atomic force microscopy
by Stephen D. Hudson, Vladimir Zhurov, Vojislava Grbić, Miodrag Grbić, and Jeffrey L. Hutter. J. Appl. Phys. 113, 154307 (2013); http://dx.doi.org/10.1063/1.4800865 (7 pages) Published online 16 April 2013

The paper is behind a paywall.

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“Spring is like a perhaps hand,” E. E. Cummings, Harvard, and nano flowers

Friday, May 17th, 2013

It’s always a treat to read a news/press/media release that starts with poetry. From the May 16, 2013 Harvard University press release,

“Spring is like a perhaps hand,” wrote the poet E. E. Cummings: “carefully / moving a perhaps / fraction of flower here placing / an inch of air there… / without breaking anything.”

This was written to celebrate the publication of a paper by Wim L. Noorduin and others, from the press release (Note: Links have been removed),

By simply manipulating chemical gradients in a beaker of fluid, Wim L. Noorduin, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS) and lead author of a paper appearing on the cover of the May 17 issue of Science, has found that he can control the growth behavior of these crystals to create precisely tailored structures.

“For at least 200 years, people have been intrigued by how complex shapes could have evolved in nature. This work helps to demonstrate what’s possible just through environmental, chemical changes,” says Noorduin.

The precipitation of the crystals depends on a reaction of compounds that are diffusing through a liquid solution. The crystals grow toward or away from certain chemical gradients as the pH of the reaction shifts back and forth. The conditions of the reaction dictate whether the structure resembles broad, radiating leaves, a thin stem, or a rosette of petals.

…

Replicating this type of effect in the laboratory was a matter of identifying a suitable chemical reaction and testing, again and again, how variables like the pH, temperature, and exposure to air might affect the nanoscale structures.

The project fits right in with the work of Joanna Aizenberg, an expert in biologically inspired materials science, biomineralization, and self-assembly, and principal investigator for this research.

Aizenberg is the Amy Smith Berylson Professor of Materials Science at Harvard SEAS, Professor of Chemistry and Chemical Biology in the Harvard Department of Chemistry and Chemical Biology, and a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard.

Here are some details about how the scientists created their ‘flowers, from the press release,

To create the flower structures, Noorduin and his colleagues dissolve barium chloride (a salt) and sodium silicate (also known as waterglass) into a beaker of water. Carbon dioxide from air naturally dissolves in the water, setting off a reaction which precipitates barium carbonate crystals. As a byproduct, it also lowers the pH of the solution immediately surrounding the crystals, which then triggers a reaction with the dissolved waterglass. This second reaction adds a layer of silica to the growing structures, uses up the acid from the solution, and allows the formation of barium carbonate crystals to continue.

“You can really collaborate with the self-assembly process,” says Noorduin. “The precipitation happens spontaneously, but if you want to change something then you can just manipulate the conditions of the reaction and sculpt the forms while they’re growing.”

Increasing the concentration of carbon dioxide, for instance, helps to create ‘broad-leafed’ structures. Reversing the pH gradient at the right moment can create curved, ruffled structures.

Noorduin and his colleagues have grown the crystals on glass slides and metal blades; they’ve even grown a field of flowers in front of President Lincoln’s seat on a one-cent coin.

“When you look through the electron microscope, it really feels a bit like you’re diving in the ocean, seeing huge fields of coral and sponges,” describes Noorduin. “Sometimes I forget to take images because it’s so nice to explore.”

Here’s a link to and a citation for the paper,

Rationally Designed Complex, Hierarchical Microarchitectures by Wim L. Noorduin, Alison Grinthal, L. Mahadevan, and Joanna Aizenberg. Science 17 May 2013: Vol. 340 no. 6134 pp. 832-837 DOI: 10.1126/science.1234621

H/T to the May 17, 2013 news item on Azonano.

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Emory University’s Shuming Nie discusses Iron Man 3 and nanotechnology and researchers develop an injectable nano-network

Monday, May 6th, 2013

I have written about Iron Man 3 before (my May 11, 2012 posting) in the context of its nanotechnology inspirations, specifically, the Extremis Armor. For anyone not familiar with the story, I have a few bits which will bring you up to speed before getting to Shuming Nie’s commentary and some recent research into injectable nano-networks, which seems highly relevant to the Iron Man 3 discourse. First, here’s an excerpt from my May 11, 2012 posting,

In a search for Extremis, I found out that this story reboots the Iron Man mythology by incorporating nanotechnology and alchemy to create a new armor, the Extremis Armor, from the Extremis Armor website (I strongly suggest going to the website and reading the full text which includes a number of illustrative images if you find this sort of thing interesting),

When a bio-tech weapon of mass destruction was unleashed, Tony Stark threw himself onto the bleeding edge between science and alchemy, combining nanotechnology and his Iron Man armor.  The result, which debuted in Iron Man, Vol. IV, issue 5, was the Extremis Armor, Model XXXII, Mark I, which made him the most powerful hero in the world–but not without a price.

…

There were two key parts to this Extremis-enhanced suit.  The first part is the golden Undersheath, the protective interface between Stark’s nervous system and the second chief part, the External Suit Devices (ESDs), a.k.a. the red armor plating.

The Undersheath to the Iron Man suit components was super-compressed and stored in the hollows of Stark’s bones. The sheath material exited through skeletal pores and slid between all cells to self-assemble a new “skin” around him.  This skin provides a complete interface to the Iron Man suit components and can perform numerous other functions. (The process in reverse withdrew the Undersheath back into these specially modified areas of Tony Stark’s bone marrow tissue.)

The Undersheath is a nano-network that incorporates peptide-peptide logic (PPL), a molecular computational system made of superconducting plastic impregnated molecular chains. [my emphasis added for May.6.13 posting]  The PPL handles, among other things: memory, critical logic paths, comparative “truth” tables, automatic response look-up tables, data storage, communication, and external sensing material interface.

The lattice assembly is a stress-compression truss with powered interstitial joints.  This can surround the PPL material and guide it through Stark’s body.  This steerable, motile lattice framework is commanded by the PPL molecule computational mentality.  The metallic component to the lattice is a controlled mimetic artifact that can take on the characteristics of most elements.  Even unusual combinations of behaviors such as extreme hardness and flexibility.

The combination of the two nano-scale materials allows for a very dense non-traditional computer that can change the fabric of its design in very powerful ways. The incorporation of the Undersheath in Stark’s entire nervous system renders reflex-level computer responses to pan-spectrum stimuli.

Anthony Stark’s Bio/Metalo-Mimetic Material concept is a radical departure from the traditional solid-state underpinnings of his prior Iron Man suit designs.  Making use of nano-scale assembly technology, “smart” molecules can be made atom by atom. The design allows for simple computers to be linked into a massive parallel computer that synthesizes human thought protocols.

The External Suit Devices (ESDs), the red armor plates, were made via mega-nano technology that has assembled atoms into large, discreet effectors.  This allows for the plates to be collapsable to very small volumes for easy storage and carried in Stark’s briefcase. The ESDs were commanded by the Undersheath and were self-powered by high-capacity Kasimer plates.  They were equipped with large arrays of nano-fans that allow flight.  Armoring-up was done by drawing the suit to Stark via a vectored repulsor field, just lightly pushing them from different angles.

The armor’s memory-metal technology renders it lightweight and flexible while not in use, but extremely durable when polarized.  The armor was strong, of course, but it could be made even stronger by rerouting repulsor input to reinforce the armor’s mass.

Stark’s skin is now a part of the suit, when engaged.  [emphasis mine] Comfort is relative because the suit rapidly responds to any discomfort, from impacts to high temperatures, from itching to scratching.  The suit’s protocols include semi-autonomy when needed.  Where Stark ends and the suit begins is flexible.  The exact nature of the artificial Extremis Virus is not known (especially because Stark recompiled the dose, then tweaked the nutrients and suspended metals, radically altering Maya Hansen’s [the character Rebecca Hall will reputedly play] formulations).  The effect it has had on Stark’s body is to allow the presence of so much alien material within his body without trauma.

Because of the bio-interface between Tony and the armor, he could utilize the suit to its fullest potential and also instantly access computers and any digital system worldwide at the speed of thought.  He was biologically integrated with his armor, one with it, imbued with unprecedented powers and abilities.  He channeled and processed data, emergency signals, and satellite reconnaissance from every law enforcement, military, and intelligence service in the world–in his head.  He could send electronic signals and make phone calls with his mind.  He could see through satellites.  Plus he had the ability to transmit whatever he saw (from his visual cortex) to other people’s display screens.  The computer’s cybernetic link enables him to operate all of the armor’s functions, as well as providing a remote link to other computers (as Stark is now part of the armor this connection is seamless).  The armor’s system was connected to the global mainframe via StarkTech servers.

I also like this more generalized description of the technology in the Wikipedia essay on Extemis Comics (Note: A link has been removed),

Extremis has been referred to as a “virus” constantly since the story. The verbatim description offered by its inventor Maya Hansen, goes: “…Extremis is a super-soldier solution. It’s a bio-electronics package, fitted into a few billion graphite nanotubes and suspended in a carrier fluid. [emphasis mine] A magic bullet, like the original super-soldier serum—all fitted into a single injection. It hacks the body’s repair center—the part of the brain that keeps a complete blue print of the human body. When we’re injured, we refer to that area of the brain to heal properly. Extremis rewrites the repair center. In the first stage, the body essentially becomes an open wound. The normal human blueprint is being replaced with the Extremis blueprint. The brain is being told the body is wrong. Extremis protocol dictates that the subject be placed on life support and intravenously fed nutrients at this point. For the next two or three days, the patient remains unconscious within a cocoon of scabs. (…) Extremis uses the nutrients and body mass to grow new organs. Better ones…”

A Postmedia movie reviewer, Katherine Monk noted this about the plot in her May 3, 2013 review of Iron Man 3 ,

Apparently, back in the early days of genetic engineering, a brilliant, zit-faced scientist (Guy Pearce) offered Tony a piece of a lucrative patent that had the potential to alter the human body, and even regenerate amputated limbs.

Tony walked away from the offer as well as the pretty girl (Rebecca Hall) who worked for the genetic engineer, but in the opening sequence, we see the technology was successfully developed and tested. It makes people superhuman, but it can also make them spontaneously combust, leaving great craters and human casualties behind.

Now for the video commentary, Dr. Shuming Nie, Biomedical Engineering at Emory University, offers some scientific insight into the science and the fiction of ‘extremis’ as per Iron Man 3 in his YouTube video,

Keeping on the science theme,  researchers at North Carolina State University (NCSU) and other institutions announced an injectable nano-network for diabetics in a May 3, 2013 news release on EurekAlert,

In a promising development for diabetes treatment, researchers have developed a network of nanoscale particles that can be injected into the body and release insulin when blood-sugar levels rise, maintaining normal blood sugar levels for more than a week in animal-based laboratory tests. The work was done by researchers at North Carolina State University, the University of North Carolina at Chapel Hill, the Massachusetts Institute of Technology and Children’s Hospital Boston.

“We’ve created a ‘smart’ system that is injected into the body and responds to changes in blood sugar by releasing insulin, effectively controlling blood-sugar levels,” says Dr. Zhen Gu, lead author of a paper describing the work and an assistant professor in the joint biomedical engineering program at NC State and UNC Chapel Hill. “We’ve tested the technology in mice, and one injection was able to maintain blood sugar levels in the normal range for up to 10 days.”

Here’s how the smart system is achieved,

The new, injectable nano-network is composed of a mixture containing nanoparticles with a solid core of insulin, modified dextran and glucose oxidase enzymes. When the enzymes are exposed to high glucose levels they effectively convert glucose into gluconic acid, which breaks down the modified dextran and releases the insulin. The insulin then brings the glucose levels under control. The gluconic acid and dextran are fully biocompatible and dissolve in the body.

Each of these nanoparticle cores is given either a positively charged or negatively charged biocompatible coating. The positively charged coatings are made of chitosan (a material normally found in shrimp shells), while the negatively charged coatings are made of alginate (a material normally found in seaweed).

When the solution of coated nanoparticles is mixed together, the positively and negatively charged coatings are attracted to each other to form a “nano-network.” Once injected into the subcutaneous layer of the skin, the nano-network holds the nanoparticles together and prevents them from dispersing throughout the body. Both the nano-network and the coatings are porous, allowing blood – and blood sugar – to reach the nanoparticle cores.

“This technology effectively creates a ‘closed-loop’ system that mimics the activity of the pancreas in a healthy patient, releasing insulin in response to glucose level changes,” Gu says. “This has the potential to improve the health and quality of life of diabetes patients.”

For anyone who’s interested in researching further, heres’ a citation for and a link to the paper,

Injectable Nano-Network for Glucose-Mediated Insulin Delivery by Zhen Gu, Alex A. Aimetti, Qun Wang, Tram T. Dang, Yunlong Zhang, Omid Veiseh, Hao Cheng, Robert S. Langer, and Daniel G. Anderson. ACS Nano, Article ASAP DOI: 10.1021/nn400630x Publication Date (Web): May 2, 2013

Copyright © 2013 American Chemical Society

The paper is behind a paywall. Meanwhile, there are discussions about moving these injectable nano-networks into human clinical trials. As Nie notes, Iron Man 3 hints at new medical technologies which will be achievable in the next 10 or so years, although we may have to wait 100 to 150 years for  Extremis armor.

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Harvard University researcher Chirarattananom’s Flight of the RoboBee

Friday, May 3rd, 2013

The flight of  Chirarattananom’s RoboBee took place last summer but the research has only now been published. There’s a May 2, 2013 news release on EurekAlert heralding this robotic first from 2012,

In the very early hours of the morning, in a Harvard robotics laboratory last summer, an insect took flight. Half the size of a paperclip, weighing less than a tenth of a gram, it leapt a few inches, hovered for a moment on fragile, flapping wings, and then sped along a preset route through the air.

Like a proud parent watching a child take its first steps, graduate student Pakpong Chirarattananon immediately captured a video of the fledgling and emailed it to his adviser and colleagues at 3 a.m.—subject line, “Flight of the RoboBee.”

“I was so excited, I couldn’t sleep,” recalls Chirarattananon, co-lead author of a paper published this week in Science.

The demonstration of the first controlled flight of an insect-sized robot is the culmination of more than a decade’s work, led by researchers at the Harvard School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard.

Here’s what it looks like,

The tiny robot flaps its wings 120 times per second using piezoelectric actuators -- strips of ceramic that expand and contract when an electric field is applied. Thin hinges of plastic embedded within the carbon fiber body frame serve as joints, and a delicately balanced control system commands the rotational motions in the flapping-wing robot, with each wing controlled independently in real-time. Credit: Kevin Ma and Pakpong Chirarattananon, Harvard University.

The tiny robot flaps its wings 120 times per second using piezoelectric actuators — strips of ceramic that expand and contract when an electric field is applied. Thin hinges of plastic embedded within the carbon fiber body frame serve as joints, and a delicately balanced control system commands the rotational motions in the flapping-wing robot, with each wing controlled independently in real-time.
Credit: Kevin Ma and Pakpong Chirarattananon, Harvard University.

The Harvard [University] Gazette May 2, 2013 article by Caroline Perry, which originated the news release, provides more detail about what makes this particular robotic work unique,

“We had to develop solutions from scratch, for everything,” explains Wood [Robert J. Wood, Charles River Professor of Engineering and Applied Sciences at SEAS, Wyss core faculty member, and principal investigator of the National Science Foundation-supported RoboBee project]. “We would get one component working, but when we moved onto the next, five new problems would arise. It was a moving target.”

Flight muscles, for instance, don’t come prepackaged for robots the size of a fingertip.

“Large robots can run on electromagnetic motors, but at this small scale you have to come up with an alternative, and there wasn’t one,” says co-lead author Kevin Y. Ma, a graduate student at SEAS.

The tiny robot flaps its wings with piezoelectric actuators — strips of ceramic that expand and contract when an electric field is applied. Thin hinges of plastic embedded within the carbon fiber body frame serve as joints, and a delicately balanced control system commands the rotational motions in the flapping-wing robot, with each wing controlled independently in real time.

At tiny scales, small changes in airflow can have an outsized effect on flight dynamics, and the control system has to react that much faster to remain stable.

While it’s called the RoboBee project, the researchers’ inspiration for this prototype is a fly. Unlike most flies, this one is tethered, at least for now (from Perry’s article),

The prototypes are still tethered by a very thin power cable because there are no off-the-shelf solutions for energy storage that are small enough to be mounted on the robot’s body. High-energy-density fuel cells must be developed before the RoboBees will be able to fly with much independence.

Future research plans include (from Perry’s article),

… integrating the parallel work of many different research teams that are working on the brain, the colony coordination behavior, the power source, and so on, until the robotic insects are fully autonomous and wireless.

Here’s a citation for and a link to the research paper,

Controlled Flight of a Biologically Inspired, Insect-Scale Robot by Kevin Y. Ma,  Pakpong Chirarattananon,  Sawyer B. Fuller, and Robert J. Wood. Science 3 May 2013: Vol. 340 no. 6132 pp. 603-607 DOI: 10.1126/science.1231806

The paper is behind a paywall.

On reading about the RoboBee project I was reminded of Michael Crichton’s 2002 cautionary tale, Prey, which focuses on a possible future where small, swarming bots that fly threaten to take over the world. More happily, I was also inspired musically and found this rendition of the Flight of the Bumblebee,

Have a nice Friday, May 3, 2013!

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Seeing things from a bug’s perspective—a new type of digital camera

Thursday, May 2nd, 2013
The new digital cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods

The new digital cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods

A May 1, 2013 news item on Nanowerk provides some details about a new ‘bug-eyed’ digital camera,

An interdisciplinary team of researchers has created the first digital cameras with designs that mimic those of ocular systems found in dragonflies, bees, praying mantises and other insects. This class of technology offers exceptionally wide-angle fields of view, with low aberrations, high acuity to motion, and nearly infinite depth of field.

Taking cues from Mother Nature, the cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods. The devices combine soft, rubbery optics with high performance silicon electronics and detectors, using ideas first established in research on skin and brain monitoring systems by John A. Rogers, a Swanlund Chair Professor at the University of Illinois at Urbana-Champaign, and his collaborators.

The May 1, 2013 University of Illinois news release by John Kubetz, which originated the news item, describes the special properties of an insect eye and how the camera mimics those properties,

Eyes in arthropods use compound designs, in which arrays of smaller eyes act together to provide image perception. Each small eye, known as an ommatidium, consists of a corneal lens, a crystalline cone, and a light sensitive organ at the base. The entire system is configured to provide exceptional properties in imaging, many of which lie beyond the reach of existing man-made cameras.

The researchers developed new ideas in materials and fabrication strategies allowing construction of artificial ommatidia in large, interconnected arrays in hemispherical layouts. Building such systems represents a daunting task, as all established camera technologies rely on bulk glass lenses and detectors constructed on the planar surfaces of silicon wafers which cannot be bent or flexed, much less formed into a hemispherical shape.

“A critical feature of our fly’s eye cameras is that they incorporate integrated microlenses, photodetectors, and electronics on hemispherically curved surfaces,” said Jianliang Xiao, an assistant professor of mechanical engineering at University of Colorado Boulder and coauthor of the study. “To realize this outcome, we used soft, rubbery optics bonded to detectors/electronics in mesh layouts that can be stretched and deformed, reversibly and without damage.”

On a more technical note, from the news release,

The fabrication starts with electronics, detectors and lens arrays formed on flat surfaces using advanced techniques adapted from the semiconductor industry, said Xiao [Jianliang Xiao, an assistant professor of mechanical engineering at University of Colorado Boulder and coauthor of the study], who began working on the project as a postdoctoral researcher in Rogers’ lab at Illinois. The lens sheet—made from a polymer material similar to a contact lens—and the electronics/detectors are then aligned and bonded together. Pneumatic pressure deforms the resulting system into the desired hemispherical shape, in a process much like blowing up a balloon, but with precision engineering control.

The individual electronic detectors and microlenses are coupled together to avoid any relative motion during this deformation process. Here, the spaces between these artificial ommatidia can stretch to allow transformation in geometry from planar to hemispherical. The electrical interconnections are thin, and narrow, in filamentary serpentine shapes; they deform as tiny springs during the stretching process.

According to the researchers, each microlens produces a small image of an object with a form dictated by the parameters of the lens and the viewing angle. An individual detector responds only if a portion of the image formed by the associated microlens overlaps the active area. The detectors stimulated in this way produce a sampled image of the object that can then be reconstructed using models of the optics.

Katherine Bourzac in her May 1, 2013 article for Nature magazine provides some additional insight and a perspective (intentional wordplay) from a researcher who has an idea of how he might like to integrate this new type of camera into his own work,

Insect eyes are made up of hundreds or even thousands of light-sensing structures called ommatidia. Each contains a lens and a cone that funnels light to a photosensitive organ. The long, thin ommatidia are bunched together to form the hemispherical eye, with each ommatidium pointing in a slightly different direction. This structure gives bugs a wide field of view, with objects in the periphery just as clear as those in the centre of the visual field, and high motion sensitivity. It also allows a large depth of field — objects are in focus whether they’re nearby or at a distance.

…

“The whole thing [the new digital camera] is stretchy and thin, and we blow it up like a balloon” so that it curves like a compound eye, says Rogers. The current prototype produces black-and-white images only, but Rogers says a colour version could be made with the same design.

…

With the basic designs in place, Rogers says, his team can now increase the resolution of the camera by incorporating more ommatidia. “We’d like to do a dragonfly, with 20,000 ommatidia,” he says, which will require some miniaturization of the components.

Alexander Borst, who builds miniature flying robots at the Max Planck Institute of Neurobiology in Martinsried, Germany, says that he is eager to integrate the camera into his machines. Insects’ wide field of vision helps them to monitor and stabilize their position during flight; robots with artificial compound eyes might be better fliers, he says.

For interested parties, here’s a link to and a citation for the research paper,

Digital cameras with designs inspired by the arthropod eye by Young Min Song, Yizhu Xie, Viktor Malyarchuk, Jianliang Xiao, Inhwa Jung, Ki-Joong Choi, Zhuangjian Liu, Hyunsung Park, Chaofeng Lu, Rak-Hwan Kim, Rui Li, Kenneth B. Crozier, Yonggang Huang, & John A. Rogers.
Nature 497, 95–99 (02 May 2013) doi:10.1038/nature12083 Published online 01 May 2013

This article is behind a paywall.

I last mentioned John A. Rogers and the University of Illinois in a Feb. 28, 2013 posting about a bendable, stretchable lithium-ion battery.

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Bend it, twist it, roll it—composites inspired by nature

Tuesday, April 16th, 2013

Researchers at ETH (Swiss Federal Institute of Technology) Zurich have developed a new composite material with bioinspired microstructures, from the Apr. 16, 2013 news item on Nanowerk,

Plant components that bend, roll or twist in response to external stimuli such as temperature or moisture are fairly commonplace in nature and often play a role in the dispersal of seeds. Pine cones, for instance, close their scales when wet and open them again once they have dried out. André Studart, a professor of complex materials at ETH Zurich’s Department of Materials, and his group have now applied the knowledge of how these movements come about to produce synthetically a composite material with comparable properties …

The Apr. 16, 2013 ETH Zurich news article by Maja Schaffner, which originated the news item, goes on to describe how the pine cone comes by its abilities,

Studart and co-workers knew from the literature how pine cone scales work: two firmly connected layers lying on top of each other inside a scale are responsible for the movement. Although the two layers consist of the same swellable material, they expand in different ways under the influence of water because of the rigid fibres enclosed in the layers. In each of the layers, these are specifically aligned, thus determining the direction of expansion. Therefore, when wet only one of the two layers expands in the longitudinal direction of the scale and bends on the other side.

The scientists then devised an artificial means of achieving the pine cone’s ability to swell in two orientations (from the article),

Inspired by nature, the scientists began to produce a similar moving material in the lab by adding ultrafine aluminium oxide platelets as the rigid component to gelatine – the swellable base material – and pouring it into square moulds. The surface of the aluminium oxide platelets is pre-coated with iron oxide nanoparticles to make them magnetic. This enabled the researchers to align the platelets in the desired direction using a very weak rotating magnetic field. On the cooled and hardened first layer, they poured a second one with the same composition, differing only in the direction of the rigid elements.

…

The scientists cut this double-layered material into strips. Depending on the direction in which these strips were cut compared to the direction of the rigid elements in the gelatine pieces, the strips bent or twisted differently under the influence of moisture: some coiled lengthwise like a pig’s tail, others turned loosely or very tightly on their own axis to form a helix reminiscent of spiral pastries. “Meanwhile, we can programme the way in which a strip should take shape fairly accurately,” explains Studart.

The researchers also produced longer strips that behave differently in different sections – curl in the first section, for instance, then bend in one direction and the other in the final section. Or they created strips that expanded differently length and breadthwise in different sections in water. And they also made strips from another polymer that responded to both temperature and moisture – with rotations in different directions.

However, Studart was most interested in rotational movements (from the article),

“Bending movements,” he says, “are relatively straightforward.” Metallic bilayer compounds that bend upon temperature changes are widely used in thermostats, for instance. The new method, however, is largely material-independent, which means that any material that responds to external stimuli – and, according to Studart, there are quite a few – can potentially be rendered self-shaping. “Even the solid component is freely selectable and can be made magnetically responsive through the iron-oxide coating,” he says.

Here’s a link to and a citation for the article,

Self-shaping composites with programmable bioinspired microstructures by Randall M. Erb, Jonathan S. Sander, Roman Grisch, & André R. Studart. Nature Communications 4, Article number: 1712 doi:10.1038/ncomms2666 Published 16 April 2013

This article is behind a paywall.

According to Schaffner’s article, Studart believes this work could have applications in the field of medical devices and for self-shaping ceramic devices.

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Bedbugs: a bean-based solution from the Balkans or an artificial spider web solution from Fibertrap

Wednesday, April 10th, 2013

Today (Apr. 10, 2013), I came across two news items about ridding oneself of bedbugs. Given the amount of coverage the pests and their growing ubiquity have been receiving the last few years, it seems that at some point everyone will experience an infestation. So, it’s good to see that scientists and entrepreneurs are working on solutions.

First up, there’s a team of scientists who are studying how people in the Balkans rid themselves of bedbugs, from the Apr. 9, 2013 news item on ScienceDaily,

Inspired by a traditional Balkan bedbug remedy, researchers have documented how microscopic hairs on kidney bean leaves effectively stab and trap the biting insects, according to findings published online today [Apr. 9, 2013] in the Journal of the Royal Society Interface. Scientists at UC [University of California] Irvine and the University of Kentucky are now developing materials that mimic the geometry of the leaves.

I knew they were a problem but I hadn’t realized how very hardy the bugs are, from the news item,

Bedbugs have made a dramatic comeback in the U.S. in recent years, infesting everything from homes and hotels to schools, movie theaters and hospitals. Although not known to transmit disease, their bites can cause burning, itching, swelling and psychological distress. It helps to catch infestations early, but the nocturnal parasites’ ability to hide almost anywhere, breed rapidly and “hitchhike” from place to place makes detection difficult. They can survive as long as a year without a blood meal.

Current commercial prevention methods, including freezing, extreme heating, vacuuming and pesticides, can be costly and unreliable. Many sufferers resort to ineffective, potentially dangerous measures, such as spraying nonapproved insecticides themselves rather than hiring a professional.

The University of California Irvine Apr. 9, 2013 news release, which originated the news item, describes the researchers’ [Doctoral student Megan Szyndler, entomologist Catherine Loudon and chemist Robert Corn of UC Irvine and entomologists Kenneth Haynes and Michael Potter of the University of Kentucky] inspiration, the bean leaves, at more length and the proposed bedbug solution,

Their work was motivated by a centuries-old remedy for bedbugs used in Bulgaria, Serbia and other southeast European countries. Kidney bean leaves were strewn on the floor next to beds and seemed to ensnare the blood-seeking parasites on their nightly forays. The bug-encrusted greenery was burned the next morning to exterminate the insects.

Through painstaking detective work, the scientists discovered that the creatures are trapped within seconds of stepping on a leaf, their legs impaled by microscopic hooked hairs known botanically as trichomes.

Using the bean leaves as templates, the researchers have microfabricated materials that closely resemble them geometrically. The synthetic surfaces snag the bedbugs temporarily but do not yet stop them as effectively as real leaves, Loudon said, suggesting that crucial mechanics of the trichomes still need to be determined.

Theoretically, bean leaves could be used for pest control, but they dry out and don’t last very long. They also can’t easily be applied to locations other than a floor. Synthetic materials could provide a nontoxic alternative.

“Plants exhibit extraordinary abilities to entrap insects,” said Loudon, lead author of the paper. “Modern scientific techniques let us fabricate materials at a microscopic level, with the potential to ‘not let the bedbugs bite’ without pesticides.”

“Nature is a hard act to follow, but the benefits could be enormous,” Potter said. “Imagine if every bedbug inadvertently brought into a dwelling was captured before it had a chance to bite and multiply.”

Here’s a citation and link to the article,

Entrapment of bed bugs by leaf trichomes inspires microfabrication of biomimetic surfaces by Megan W. Szyndler,  Kenneth F. Haynes, Michael F. Potter, Robert M. Corn,
and Catherine Loudon. J. R. Soc. Interface. 2013 10 83 20130174; doi:10.1098/rsif.2013.0174 (published 10 April 2013) 1742-5662

This article is open access.

Moving onto the second bedbug item, Azonano features an Apr. 10, 2013 news item about Fibertrap and its artificial spider web trap for bedbugs,

A breakthrough and innovative solution to the growing plague of bedbugs is about to impact the lives of people suffering from one of the world’s most tenacious pests. Fibertrap is a New York based firm that has developed a revolutionary new way to stop bedbugs, termites and other pests without the use of harmful and toxic chemicals and instead by using an artificial, micro-fiber spider web.

Here’s more about how this solution works,

As the war against bedbugs rages on these nasty insects have become increasingly resistant to pesticides and other common methods of pest control. Fibertrap’s ground-breaking new method addresses the fundamental weakness in all bedbugs and pests: mobility. Utilizing micro-fibers 50 times thinner than human hair, Fibertrap entangles the bugs as they crawl trapping them in the man-made web. Without the ability to move and seek food the creatures will die, ceasing re-production and preventing the establishment of infestation.

Most often, bedbugs move between walls via electrical outlets to unsuspecting home and business owners. To help prevent bedbug migration, Fibertrap intends to produce easy to use traps and insulation products using this innovative new web-like material that will allow the consumer to protect their homes, apartments, offices and dorm rooms with ease and peace of mind.

You can read more about it at Azonano or you can try the Fibertrap website. I cannot find any information about purchasing a Fibertrap product. I think this is publicity designed to excite interest and further investment so these materials ,which are currently at a prototype stage, can be brought to market.

I hope someone is able to get a pest control product for bedbugs to us soon.

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