First step towards 'programmable materials'

First step towards 'programmable materials': The working model used by the researchers consists of a one-meter by one-centimeter aluminum plate that is one millimeter thick. This sheet-metal strip can vibrate at different frequencies. In order to control the wave propagation, ten small aluminum cylinders (7 mm thick, 1 cm high) are attached to the metal. Between the sheet and the cylinders sit piezo discs, which can be stimulated electronically and change their thickness in a flash. This ultimately enables the team headed by project supervisor Andrea Bergamini to control exactly whether and how waves are allowed to propagate in the sheet-metal strip. The aluminum strip thus turns into a so-called adaptive phononic crystal – a material with adaptable properties.

Zinc Oxide Nanowires Transistors Can Be Sophisticated Pressure Sensors | MIT Technology Review

Zinc Oxide Nanowires Transistors Can Be Sophisticated Pressure Sensors | MIT Technology Review: In the new research, Wang’s group demonstrates nanoelectronics that offer at least a 15-fold enhancement in sensor density and spatial resolution compared to the previous approaches... The density, resolution, and sensitivity of the sensors, says Wang, is comparable to that of the skin of a human finger...

In Wang’s nanowire transistors, the gate traditionally used in electronics is eliminated. Instead, the current flowing through the nanowires is controlled by the electrical charge generated when strain or force applied is to the transistors.

Artificial muscle computer performs as a universal Turing machine

Artificial muscle computer performs as a universal Turing machine: The artificial muscle computer is modeled on Stephen Wolfram's "2, 3" Turing machine architecture, which is the simplest known universal Turing machine...


In its current version, the artificial muscle computer is very large (about 1 m3) and extremely slow (0.15 Hz).

Acoustic tweezers capture tiny creatures with ultrasound (w/ Video)

Acoustic tweezers capture tiny creatures with ultrasound (w/ Video): Acoustic tweezers use ultrasound, the same noninvasive technology doctors use to capture images of the fetus in the womb. The device is based on piezoelectric material that moves when under an electrical current. The vibrations pass through transducers attached to the piezoelectric substrate, where they are converted into standing surface acoustic waves (SAWs). The SAWs create pressure fields in the liquid medium that hold the specimen...
"We believe the device can be easily manufactured at a cost far lower than say, optical tweezers, which use lasers to manipulate single particles," said Tony Jun Huang, associate professor of bioengineering, whose group pioneered acoustic tweezers. "Optical tweezers require power densities 10,000,000 times greater than our acoustic tweezers, and the lasers can heat up and damage the cells, unlike ultrasound."

'Flying carpet': Princeton team's plastic sheet can hover above ground (w/ video)

'Flying carpet': Princeton team's plastic sheet can hover above ground (w/ video): "We use integrated piezoelectric actuators and sensors to demonstrate the propulsive force produced by controllable transverse traveling waves in a thin plastic sheet suspended in air above a flat surface, thus confirming the physical basis for a 'flying' carpet near a horizontal surface," wrote the three authors, Noah Jafferis, Howard Stone, and James Sturm. “Experiments are conducted to determine the dependence of the force on the height above the ground and the amplitude of the traveling wave, which qualitatively confirm previous theoretical predictions.”

The First Quantum Machine | Science/AAAS

The First Quantum Machine | Science/AAAS: A team of American physicists found a quicker route, as they reported in March. Instead of a beam, they fashioned a tiny diving board of aluminum nitride plated with aluminum that vibrated by getting thinner and thicker. As the doohickey hummed away at a very high frequency—a whopping 6 billion cycles per second—the “piezoelectric” material in it produced a warbling electric field that was easy to detect. Most important, through that field, the physicists managed to “couple” the mechanical device to an electronic one called a “phase qubit,” a ring of superconductor that itself has one low-energy and one high-energy quantum state.

Manipulating the qubit with microwaves, the researchers could use it to feed energy quanta into the oscillator or pull them out of it, as one might use an ATM to deposit a $20 bill to a bank account or withdraw one. First they showed that when they cooled the oscillator to a few hundredths of a degree they could get no quanta out of it. That meant it had to be in the cashed-out ground state, jiggling with only zero-point motion. The researchers then put the oscillator in a state with exactly one more quantum of energy. They even coaxed it into both states at once, so that it was literally moving two different amounts simultaneously.

Sound can leap across a vacuum after all - New Scientist - New Scientist

Sound can leap across a vacuum after all: Now a theoretical analysis by Mika Prunnila and Johanna Meltaus, both of the VTT Technical Research Centre of Finland in Espoo, suggests that sound may be able to leap across a vacuum separating two objects made of piezoelectric crystals. These crystals generate an electric field when squeezed or stretched by sound waves or other forces, and deform in an electric field.

When a sound wave reaches the edge of one crystal, the electric field associated with it can stretch across the gap and deform the crystal on the other side, creating sound waves in that second crystal (Physical Review Letters, vol 105, p 125501). "It is as if the sound waves don't even recognise the vacuum - they just go through," says Prunnila.