Tag Archives: mechanical engineering

DNA hinges

Nano-machines made from DNA look like molecule-size hinges

For the very first time, engineers have used the DNA origami assembly method to build  complex DNA-based mechanism that performs a repeatable and reversible function. Mechanical engineers at The Ohio State University built their devices such that they may function like any regular macro-object, like opening and closing hinges. Their approach, however, is different than other DNA assembly projects which concentrated on mimicking biological systems or static shapes. Such dynamic molecule-sized devices could be used in smart drug delivery or self-assembling tiny transformers-like robots.

DNA origami hinges

DNA hinges

The DNA origami method for making nano-structures has been widely used since 2006, and is now a standard procedure for many labs that are developing future drug delivery systems and electronics. It involves taking long strands of DNA and coaxing them to fold into different shapes, then securing certain parts together with “staples” made from shorter DNA strands. The resulting structure is stable enough to perform a basic task, such as carrying a small amount of medicine inside a container-like DNA structure and opening the container to release it.

[RELATED] Nanorobots made out of DNA seek and kill cancer cells

“Nature has produced incredibly complex molecular machines at the nanoscale, and a major goal of bio-nanotechnology is to reproduce their function synthetically,” saidCarlos Castro, the group project leader and an assistant professor of mechanical and aerospace engineering. “In essence, we are using a bio-molecular system to mimic large-scale engineering systems to achieve the same goal of developing molecular machines.”

A DNA origami piston. Credit:  Ohio State University.

A DNA origami piston. Credit: Ohio State University.

To get their DNA machines to function properly, the engineers designed the flexing parts out of single-stranded DNA, while those regions that were supposed to be stiff were built from snips of double-stranded DNA. In the case of hinges that repeatedly open and close, this also had to perform their operation reversibly, so the engineers attached small strands of synthetic DNA off the side of the main components. Like a hook-and-loop fastener, the strands latch onto each other when the device is closed and release when opened. To control the operations of the machine, researchers make changes to the chemical environment. The machines then respond to this stimuli accordingly.

“DNA origami enables the precise fabrication of nanoscale geometries,” the authors write. “We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements…Our results demonstrate programmable motion of 2-D and 3-D DNA origami mechanisms constructed following a macroscopic machine design approach.”

origami hinge

This approach of designing simple joints and connecting them together to make more complex working systems is common in macroscopic machine design, but this is the first time it’s been done with DNA—and the first time anyone has tuned the DNA to produce reversible actuation of a complex mechanism, as described in a paper published in  Proceedings of the National Academy of Sciences.

“I’m pretty excited by this idea,” Castro said. “I do think we can ultimately build something like a Transformer system, though maybe not quite like in the movies. I think of it more as a nano-machine that can detect signals such as the binding of a biomolecule, process information based on those signals, and then respond accordingly—maybe by generating a force or changing shape.”

 

Magnified view of the first known biological gears present at the hind legs of the issus, a fast accelerating hopping insect. The image was made using an electron microscope. (c) Malcolm Burrows

This insect is the first known creature gifted by nature with ‘mechanical gears’

Magnified view of the first known biological gears present at the hind legs of the issus, a fast accelerating hopping insect.  The image was made using an electron microscope. (c) Malcolm Burrows

Magnified view of the first known biological gears present at the hind legs of the issus, a fast accelerating hopping insect. The image was made using an electron microscope. (c) Malcolm Burrows

The Issus coleoptratus or issus for short is a small hopping insect that can leap at tremendous speeds and lengths compared to its tiny size. Actually, it’s one of the fastest accelerating creatures known to biologists, capable of accelerating at nearly 400 g’s—a rate more than 20 times what a human body can withstand. To achieve this fascinating feat the issus performs a perfectly synchronized kick of his hind legs to propel it forward at dazzling speeds, and this perfect timing is made possible using a minuscule pair of interlocking teeth-like structures. The resemblance to a man-made mechanical gear is striking and as two UK  researchers recently reported in a paper published in the journal Science, its working principle is similar as well.

Issus coleoptratus

Issus coleoptratus

The involute gear, the precursor to virtually all types of gears today, was first introduced by Swiss mathematician Leonhard Euler in the 18th century. Nature, however, beat us to it long time ago judging from the biological gears the issus is sporting. The three-millimeter hoping insect uses these gears to lock its back legs together,  allowing both appendages to rotate at the exact same instant, causing the tiny creature’s jump forward.

“In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t,” said Malcolm Burrows in a press statement.

“This emphasises the importance of considering the properties of the skeleton in how movement is produced.”

“We usually think of gears as something that we see in human designed machinery, but we’ve found that that is only because we didn’t look hard enough,” added co-author Gregory Sutton, now at the University of Bristol.

“These gears are not designed; they are evolved – representing high speed and precision machinery evolved for synchronisation in the animal world.”

(c) Malcolm Burrows

(c) Malcolm Burrows

High precision indeed: each gear features between 10 and 12 tapered teeth, each tooth is about 80 micrometers wide helping mesh the two gears neatly. Fascinating enough, each gear tooth has filleted curves at the base,  a design feature incorporated in all modern gears since it reduces wear. The gear aren’t exactly like any type of mechanical gear made by humans – they’re made for “high precision and speed in one direction,” Sutton says. “It’s a prototype for a new type of gear.”

issus jumping gears

The gearing is most definitely an elegant solution found by nature to help the issus achieve its fast and accelerated jumps. Actually, the issus engages its gears before the jumps happens, locking them together in under 30 milliseconds (1/300,000 seconds)! What truly mysterious about the issus, however, is that these gears are only present in adolescent individuals. During its development stages, the issus molts about half a dozen times, making changes and adjustments to its exoskeleton each time – gears included, which grow larger and larger with the issus itself. By the time it grows into adulthood, however, the issus loses its gears. The researchers have a possible explanation for this. If one of the gear tooth breaks, then it will severely affect the issus’ leaps, indispensable to its survival at the face of predators. An adolescent can afford to have one or more of its gear teeth to break, since it replaces them every time it molds. The adult stops molding, though, so its ineffective for it to keep the gears – it’s just too risky! “Just like if your car has a gear train missing a tooth. Every time you get to that missing tooth, the gear train jerks,” Sutton says.

Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

Detecting explosives with an artificial dog nose

In an age where the developing world is shadowed by paranoia in face of waves of terrorist attacks, no measure of precaution is spared. Preventing terrorist attacks has been a top priority for governments for a long time, especially since 9/11, and detecting explosives at critical check-ins like airport and customs makes for the first line of the defense. While we’re nearing 2013, dogs are still the gold standard for explosive detection and no man-made device has managed to come close to canine sensing accuracy – until recently that is.

Mechanical and chemical engineers at University of California, Santa Barbara have designed a detector that uses microfluidic nanotechnology to mimic the biological mechanism behind the dog’s sensing apparatus. Basically, they’ve developed a mechanical bomb sniffer based on the dog’s nose, which they claim is not only accurate, but actually more precise than the canine nose. If the device catches on – the scientists have already obtained a patent and exclusive licence – than it could become just as common in potentially hazardous zones like smoke detectors.

Previously, we’ve seen some interesting concepts for detecting explosives, from cutting-edge projects employing graphene layers to quite eccentric projects that use bee venom. The present showcased device, however, seems the most promising.

The team of researchers were led by professors Carl Meinhart of mechanical engineering and Martin Moskovits of chemistry,

“The device is capable of real-time detection and identification of certain types of molecules at concentrations of 1 ppb or below. Its specificity and sensitivity are unparalleled,” said Dr. Brian Piorek, former mechanical engineering doctoral student in Meinhart’s laboratory and Chief Scientist at Santa Barbara-based SpectraFluidics, Inc

Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

An artificial bomb sniffer puts dogs out of work

The technology works by combining two key principles  – free-surface microfluidics and surface-enhanced Raman spectroscopy (SERS) – to capture and identify molecules. One of the molecules they’ve targeted is 2,4-dinitrotoluene, the primary vapor emanating from TNT-based explosives. The substance comes in such a minute quantity that the human nose can not sense it, but dogs’ noses are sensitive enough to detect it. Inspired by the dog’s olfactory mucus layer, the scientists devised an artificial “sniffer”.

The device mainly consists of two parts – a microchannel, twenty times thinner than the human hair, which traps the target molecule for presenting it to the second part, a mini spectrometer power by a laser that detects the molecule. A computer database of spectral signatures identifies what kind of molecule has been captured, meaning that its uses are far from being limited only to detecting explosives; anything from noxious substances that can’t be senses otherwise to extremely sensitive sensors for scientific research could be employed.

“The technology could be used to detect a very wide variety of molecules,” said Meinhart. “The applications could extend to certain disease diagnosis or narcotics detection, to name a few.”

Moskovits added, “The paper we published focused on explosives, but it doesn’t have to be explosives. It could detect molecules from someone’s breath that may indicate disease, for example, or food that has spoiled.”

Their findings were published in the journal  Analytical Chemistry.

source

The lattice-shaped electrode in the foreground, and the elastomer in the background.

Inteligent shock absorbers dampen vibrations and generate power

Many efforts and funding have been put into countering vibrations, such as the ones produced by an internal combustion engine, to dampen shocks and reduce noise. Much progress has been made; you only need to compare two vehicles, one twenty years old, the other brand new, and you’ll instantly notice the differences. One, noisy and bumpy, the other silent and smooth to cruise.

There is still room for much improvement. Engineers at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt are now researching the next generation of damping elements – active elastomers.

Elastomers are highly elastic materials, most common of which being rubber, which are well suited for absorbing shock and are widely used in the field. The researchers intend on brining shock absorbing a step further, or better yet a step back – making elastomers actively react to vibrations before they get the chance to produce shock.

The lattice-shaped electrode in the foreground, and the elastomer in the background.

The lattice-shaped electrode in the foreground, and the elastomer in the background.

Imagine a top tennis player slowing the ball down on a single drop by pulling back the racket. The active elastomer envisioned by the scientists would relatively employ the same principle, drawing out the energy from vibrations through a precise push-pull mode. In theory, vibrations would dissipate completely, in practice they’d be rendered to a minimum. Worst case scenario, active elastomers are a lot more efficient than any other conventional elastomer currently used today.

The concept isn’t new, however. Materials that are similar in principle have already been developed. “They are called ‘electroactive elastomers’,” explains LBF scientist William Kaal. “They are elastic substances that change their form when exposed to an electrical field.

An applied alternative current makes the material vibrate, and if you have smart electronics applying current precisely when and where it is necessary on the material to make it vibrate in a push-pull manner, then unwanted vibrations would be easily dissipated in the most part.

To demonstrate their concept, the researchers developed a model  made out of 40 thin elastomer electrode layers, fitted with  microscopic-sized holes in the electrodes. “If an electric voltage deforms the elastomer, then the elastomer can disperse into these holes,” said Jan Hansmann. The result is an actuator that can rise or fall a few tenths of a centimeter upon command – several times a second

The device then had a small mechanical oscillator attached to it to impose vibrations. When the oscillator was turned on, the actuator soon followed its oscillations and perfectly resonated with its frequency. If the oscillator is tapped by hand, it quickly settles down when the actuator vibrates in push-pull mode.

“An engine’s vibrations can be really disruptive,” says William Kaal. “The vibrations are channeled through the chassis into the car’s interior, where the passengers start to feel them. Active elastomers may help further reduce vibrations in the car,” Kaal asserts.

When the stack actuator is reversed, from producing vibrations, to absorbing them from the environment, it produces energy. The scientists introduced an electromagnetic oscillator on their stack actuator, it converted the vibrations into power. On the same subject, read: Nanotech powered by your breath.

 “That would be of interest, for example, if you wanted to monitor inaccessible sites where there are vibrations but no power connections,” Jan Hansmann believes – as he cites an example: the temperature and vibration sensors that monitor bridges for their condition.

source: physorg

Rube Goldberg

New world record set for Rube Goldberg machine at 300 steps

Rube GoldbergEverybody enjoys a good ol’ entertaining Rube Goldberg machine, whether it’s a fantasy Loony Tunes contraption or a real-life state of the art display of engineering. What’s not to love when alarm clocks, sprockets, furniture and even boiling tea pots all work together in a lovely dance, ultimately ending in lighting a candle or something along the lines whose simplicity comes in white/black contrast with the assembly’s intricacy? This year, the Purdue Society of Professional Engineers team beat its own record after they built, yet again, the largest Rube Goldberg machine in the world, as attested by the World Records Academy.

Consisting of 300 steps, the machine flawlessly accomplished the simple task of blowing up and popping a balloon. The team spent more than 5,000 hours constructing the machine that accomplished every task ever assigned in the competition’s 25-year history, including peeling an apple, juicing an orange, toasting bread, making a hamburger, changing a light bulb, loading a CD and sharpening a pencil.

buckliball

Toy-inspired “Buckliball” paves the way towards a new class of engineering structures

buckliball

Scientist at MIT and Harvard University teamed up to figure out what would be the simplest 3-D structure capable of collapsing and morphing due to instability. Their inspiration came after the scientists came across a popular toy, spherical in shape and fitted with movable parts and hinges, which allows it to easily dimple in size reversibly. Based on this toy, the researchers created the  “buckliball,” a hollow, spherical object made of soft rubber with no movable parts, which can turn into a smaller ball, 46 percent its original size.

Its name was attributed since it resembles a buckyball, and because it makes us of the instability phenomenon known as buckling, most often in practice an effect which is sought to be avoided.

“In civil engineering, buckling is commonly associated with failure that must be avoided. For example, one typically wants to calculate the buckling criterion for columns and apply an additional safety factor, to ensure that a building stands, says  Pedro Reis, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering and Mechanical Engineering at MIT. “We are trying to change this paradigm by turning failure into functionality in soft mechanical structures. For us, the buckliball is the first such object, but there will be many others.”

The buckliball has 24 special dimples arranged in a specific pattern for optimal buckling, which was induced by researchers by sucking the air of the buckliball with a syringe. When its thing ligaments buckle, the thicker ligaments rows undergo a series of movements the researchers refer to as a “cooperative buckling cascade.” Some of these thick ligaments rotate clockwise, while other counterclockwise, but interestingly they all come together harmoniously. Thus, the buckliball morphs from a circular structure into a rhombicuboctahedron at about half of its original size.


Morphable structures which make us of predictable buckling such as the buckyball have a range of application where they might be effectively used, be it on the micro or macro scale – a football stadium with an easily collapsible buckly dome; tiny drug-delivery capsules or soft movable joints requiring no mechanical pieces.

“The buckliball not only opens avenues for the design of foldable structures over a wide range of length scales, but may also be used as a building block for creating new materials with unusual properties, capable of dramatic contraction in all directions,” says Katia Bertoldi, an assistant professor in applied mechanics at Harvard.

The findings were published in the journal Proceedings of the National Academy of Sciences.

[source MIT]

"Caught in a symbiotic relationship, both the wishbone and the machine are unable to manifest fully without the other. We drag our pasts with us and move according to unseen forces. More and more, we interface with the world through our mental and technological creations." - Arthur Ganson

Arthur Ganson’s moving sculptures

"Caught in a symbiotic relationship, both the wishbone and the machine are unable to manifest fully without the other. We drag our pasts with us and move according to unseen forces. More and more, we interface with the world through our mental and technological creations." -  Arthur Ganson

"Caught in a symbiotic relationship, both the wishbone and the machine are unable to manifest fully without the other. We drag our pasts with us and move according to unseen forces. More and more, we interface with the world through our mental and technological creations." - Arthur Ganson

Arthur Ganson is a mechanical engineer by trade and a kinetic sculptor at heart. His mechanized devices spur up spirit from cogs and wires, as his sculptures move with subtlety and grace, often in a chain reaction of energy à la Rube Goldberg. His creations are rooted inside deep philosophical concepts, but at the same time shine with an unparalleled dash of humor – a small reminder not to take life too serious.

Arthur Ganson’s art is by all means impressive, and there is no way of understanding this other than taking a remote glimpse upon these kinetic contraptions for yourself. Outlined below you’ll find some of these amazing sculptures, some decades old, alongside a brief interview with the former artist in residence at MIT himself, who was kind enough to answer some of my questions.

Machine with 23 Scraps of Paper

Machine with Cat WhiskersZME Science: The first sense I got while watching one of your sculptures was amazement. It’s quite ordinary for such a natural emotion to surface whenever you’re granted to see an animated wishbone seemingly tract its own mechanical life force. Soon after though, one begins to notice other things too. You get fascinated, seduced by it – it all feels like poetry. I can only wonder then what stream of emotions go past you, as the creator, as you go through various stages of completion before finally seeing it in motion. What’s it like?

Arthur Ganson: There are many different feelings that go through me in the process of making a piece. In the beginning, before the physical process of building the piece begins there is much light-hearted dreaming and often moments where I feel a deep inspiration. This time can be very fluid because the ‘form’ of the piece can change dramatically. It is not material yet! The building process itself has many aspects and depending on the particular piece, some things are more predominant. As a rule, no matter how much imagining I do, the piece must be built in order for me to know how well it will ‘speak’. In this regard I often feel much anticipation, especially if there is much building that must happen to se anything. Sometimes a piece will not work in the end. This can be a disappointment if I am not able to re-work the idea. The process is often filled with much determination and excitement throughout. Depending on the piece, there can be sublime moments of building or tedious moments of building…. or eureka moments or surprises……

Machine with Wishbone

ZME Science: The intricate mechanisms that you employ in your art can be viewed by many as complex, however some I’ve seen, as I did my research, believe there are many redundant parts to it. How do you believe the Rube Goldberg machine-esque approach to your mechanisms aids in amplifying the sentiment surrounding the sculpture?

Arthur Ganson: There are no un-necessary parts to the machines. Every part is there for a reason. I loved looking at Rube Goldberg drawings when I was a kid, and now his name is synonymous with absurdly complicated systems that do something very simple. I guess in one sense that’s partly true with some of my machines, but the impulse for me is not to be needlessly complex for the fun of it. When I started I was making things way more complex than necessary, but now I think I’m getting more simple and bringing things down to the essence. If they come across as rube goldbergesque is more because the observer doesn’t understand the machine. All aspects of the way something is built and exists in space will effect the nature of how it speaks emotionally. All decisions speak to the state of being of the creator.

One of Ganson's machines, dubbed "Transmutation of Cloth". (c) Chehalis Hegner

One of Ganson's machines, dubbed "Transmutation of Cloth". (c) Chehalis Hegner

Faster!

ZME Science: Much of your art seems to come to life, as various gears or wires twitch and turn in a chain of events that describe a sublime motion. This all seems so very precise, so intricate – I can only imagine the amount of time and patience you must dedicate. How do you come about building it piece by piece, aligning each part together with utmost accuracy? Do you start from somewhere and then just improvise along the way or do you work at a plan before starting, like computing, sketching and such?

Arthur Ganson: I usually start the work in my mind and then move to very general sketches that help me to visualize the overall proportions and mechanical systems and relationships. I rarely work by just starting somewhere and seeing where I end up- it’s not in my nature and usually the piece necessitates a good degree of thought in order to solve the real mechanical issues. However, nothing is a rule! Some of the fragile machines are pretty free in their evolution. Working with wire does not require a high degree of accuracy. Actually, it’s the place where I can be the most relaxed. The fragile wire pieces are the closest to oil painting that I can come. Here, I’ll create a staring point and have only a general sense of how the machine will fill space. If there is no particular mechanical problem to solve and the piece just has to move, that’s very open-ended.

Machine with Concrete - .a device made out of 12 pairs of 50-to-one reduction gears, meaning the final speed of that gear on the end is so slow that it would take two trillion years to turn once.

Machine with Concrete - .a device made out of 12 pairs of 50-to-one reduction gears, meaning the final speed of that gear on the end is so slow that it would take two trillion years to turn once.

Cory’s Yellow Chair

ZME Science: On the same subject, how does the process behind your art creation looks like? I’ve noticed that you’ve went to the extent of making your own tools for the custom work and that many of your parts are from various abandon mechanical objects. What’s your take on the objects you later use as components?

Arthur Ganson: There is much invention in the process and often it has to do with jigs and tools to make the piece. Currently I’m working on a new version of Cory’s Yellow Chair and I’m working on all kinds of jigs that will allow me to make gears with more conventional teeth- because this piece requires this in order to move properly. This is a situation in which the wire gears won’t translate power properly and the essence of the piece is it’s movement. I’m able to incorporate found objects sometimes, but I don’t have any particular take on it. Sometimes the piece is built around a found object, but I generally don’t work in a way where I’m collected a bunch of things and then try to assemble the mass into something.

For more videos of Arthur Ganson’s kinetic sculptures visit his website.