New ultrastiff, ultralight material developed | MIT News Office

New ultrastiff, ultralight material developed | MIT News Office: The actual production of such materials is made possible by a high-precision 3-D printing process called projection microstereolithography...

“We found that for a material as light and sparse as aerogel [a kind of glass foam], we see a mechanical stiffness that’s comparable to that of solid rubber, and 400 times stronger than a counterpart of similar density. Such samples can easily withstand a load of more than 160,000 times their own weight,” says Fang...

Physicists create first-ever mechanical device that measures the mass of a single molecule

Physicists create first-ever mechanical device that measures the mass of a single molecule: The device which is only a couple millionths of a meter in size consists of a tiny, vibrating bridge-like structure. When a particle or molecule lands on the bridge, its mass changes the oscillating frequency in a way that reveals how much the particle weighs...

To do so, the researchers analyzed how a particle shifts the bridge's vibrating frequency. All oscillatory motion is composed of so-called vibrational modes. If the bridge just shook in the first mode, it would sway side to side, with the center of the structure moving the most. The second vibrational mode is at a higher frequency, in which half of the bridge moves sideways in one direction as the other half goes in the opposite direction, forming an oscillating S-shaped wave that spans the length of the bridge. There is a third mode, a fourth mode, and so on. Whenever the bridge oscillates, its motion can be described as a mixture of these vibrational modes.
The team found that by looking at how the first two modes change frequencies when a particle lands, they could determine the particle's mass and position, explains Mehmet Selim Hanay, a postdoctoral researcher in Roukes's lab and first author of the paper. "With each measurement we can determine the mass of the particle, which wasn't possible in mechanical structures before."

Molecular "Wankel Engine" Driven By Photons

Molecular "Wankel Engine" Driven By Photons: A couple of year ago, chemists discovered that groups of 13 or 19 boron molecules form into concentric rings that can rotate independently, rather like the piston in a rotary Wankel engine. Because of this, they quickly picked up the moniker "molecular Wankel engines". The only question was how to power them.

Now Zhang and buddies have calculated that this should be remarkably easy--just zap them with circularly polarised infrared light. That sets the inner ring counter-rotating relative the outer one, like a Wankel engine...
What makes this one special is that the polarised light doesn't excite the molecule's electronic ground state,  leaving it free to be chemically active.

Blog - Demonstration of Actuation-at-a-Distance Effect for Labs on a Chip

Blog - Demonstration of Actuation-at-a-Distance Effect for Labs on a Chip: Today, he and his pal Matthieu Gaude put the photoelectrowetting effect into action. These guys have made a cantilever sitting above an insulated conductor and placed a droplet of water between them so that it fills the gap by capillary action (see above).

Zapping this system with light changes the wetting angle the droplet makes with the cantilever and the electrode below. This makes the droplet thinner, pulling the cantilever down.

The ability to actuate at a distance using light alone could have many applications because it eliminates the need for the complex circuitry and pumps now used to transport droplets. It could also allow optical addressing of autonomous, wireless sensors.

Holographic 3-D looks tantalizingly closer in 2012

Holographic 3-D looks tantalizingly closer in 2012: In their nanoscale system, they work with chips made by growing a layer of silicon oxide on to silicon wafer. They etch square patches of the silicon oxide. The result is a checkerboard-like pattern where etched-away pixels are nanometers lower than their neighbors. A reflective aluminum coating tops the chip. When laser light shines on the chip, it bounces off of the boundary between adjacent pixels at an angle. Diffracted light interferes constructively and destructively to create a 3-D picture where small mirrored platforms are moving up and down, many times a second, to create a moving projection. The process can also be described as the pixels closer to the light interfering with it one way and those further off, in another. The small distances between them generate the image that the eye sees.

Look ma, no hands: Engineers invent a magnetic fluid pump with no moving parts

Look ma, no hands: Engineers invent a magnetic fluid pump with no moving parts: The ferrohydrodynamic pump method works when electrodes wound around a pipe force magnetic nanoparticles within the ferrofluids to rotate at varying speeds.  Those particles closest to the electrodes spin faster, and it is this spatial variation in rotation speed that propels the ferrofluid forward. "We don't rely on any other material; no magnets, nothing moving but the ferrofluid that we're pumping," Koser says.

Mechanical micro-drum cooled to quantum ground state

Mechanical micro-drum cooled to quantum ground state: the NIST experiments nearly stop the beating motion of a microscopic aluminum drum made of about 1 trillion atoms, placing the drum in a realm governed by quantum mechanics with its energy below a single quantum, or one unit of energy. Like a plucked guitar string that plays the same tone while the sound dissipates, the drum continues to beat 11 million times per second, but its range of motion approaches zero...

In the NIST experiments, the drum is first chilled in a cryogenic refrigerator using liquid helium. This lowers the drum energy to about 30 quanta. Sideband cooling then reduces the drum temperature from 20 milliKelvin (thousandths of a degree above absolute zero) to below 400 microKelvin (millionths of a degree above absolute zero), steadily lowering the drum energy to just one-third of 1 quantum.
Scientists begin the sideband cooling process by applying a drive tone to the circuit at a particular frequency below the cavity resonance. The drumbeats generate sideband photons, which naturally convert to the higher frequency of the cavity...

How to Switch Off Friction In Nanomachines - Technology Review

How to Switch Off Friction In Nanomachines - Technology Review: Shake the surface (or the tip) and this immediately raises the tip out of this minimum, allowing it to explore the energy landscape. This is equivalent to smooth sliding, or at least smoother sliding. Vanossi and co study the relationship between the friction and vibrations of various different frequencies and amplitudes.

So the vibration dramatically reduces friction. In fact, it essentially allows friction to be switched on and off.

But Vanossi and co have another interesting result. They say that once the oscillations have overcome stick-slip friction, they can help to maintain motion. In effect, the tip can ride the oscillations, like a surfer rides ocean waves.

Make: Online � Fascinating 1953 Navy Film Series on Mechanical Computers

Make: Online � Fascinating 1953 Navy Film Series on Mechanical ComputersBefore there were elec tron ic com put ers, there were mechan i cal com put ers, and one of the most impor tant uses of these was in direct ing gun fire on sur­face war ships. Mechan i cal fire con trol com put ers took inputs from manned instru ments that visu al ly tracked enemy ships, and also con sid ered vari­ables such as wind speed and direc tion, the fir ing ship’s head ing and veloc i­ty, etc. That infor ma tion—com plete ly in the form of phys i cal dis place ments of mechan i cal move ments—was cranked through a com plex train of shafts, gears, cams, and dif fer en tials that com put ed the opti mal fir ing solu tion, and auto mat i cal ly aimed the guns accord ing ly.

Mastering bandwidth: Researchers develop tunable, low-cost laser device

Mastering bandwidth: Researchers develop tunable, low-cost laser device: The new laser is constructed using microelectromechanical systems (MEMS) technology to achieve wavelength tunability. By moving a tiny mirror, the laser switches between different operating modes, each of which produces a different wavelength. This tuning capability is built into a ‘master’ laser, which injects laser light into a secondary ‘slave’ laser. The slave laser increases the power of the emitted light, suppresses unwanted wavelengths, and allows for the encoding of information by modulating the light intensity. The two-part configuration surpasses the performance of conventional tunable lasers, without increasing bulk or cost.

Steampunk chip takes the heat - New Scientist - New Scientist

Steampunk chip takes the heat: "That prompted Te-Hao Lee's team at Case Western Reserve University in Cleveland, Ohio, to consider returning to mechanical logic. His team has developed a mechanical version of an inverter – the building block used to construct many types of logic gate, which themselves are a fundamental component of digital circuitry within computers. The device uses an arrangement of nanoscale levers instead of transistors. Like a telegraph operator's Morse key, these levers physically make and break contact to pass or block currents.

Application of a voltage makes the levers move under electrostatic attraction. At 550 °C Lee's team managed to get the inverter to switch on and off 500,000 times a second – performing a computation with each cycle."