World's Smallest Battery Yet is About as Thick as a Human Hair

Nanotechnology promises to enable tiny, intricate circuits powering devices on any surface. But unless they’re harvesting energy from something like a heartbeat, the devices can only be as small as the smallest battery.

Now researchers at Rice University have combined the two, packing an entire lithium-ion battery into a single nanowire. The developers say it’s as small as such a device can possibly get.

Researchers led by Rice professor Pulickel Ajayan built a hybrid energy storage device, which serves as a battery and a supercapacitor. The first version sandwiched an electrolyte between a nickel/tin anode and a cathode made of a polymer called polyaniline. The cathode also served as a supercapacitor, storing lithium ions in bulk, as this writeup by Rice University explains. The prototype proved that lithium ions would move through the electrolyte and into the cathode.

Then Ajayan and colleagues incorporated this structure into a single nanowire, through a complicated process of etching and chemical washing. The goal is to make nanowires with ultra-thin separation between electrodes, so the device can remain as small as possible.

The completed wire-batteries are about 50 microns tall, which is roughly the diameter of a human hair, according to Rice.

For now, they can only charge and discharge about 20 times before they die, but researchers are trying to optimize them to last longer. The research is published in the journal ACS Nano Letters.

[Popsci via PhysOrg]

Physicists Confirm Existence of New Particle

Physicists working at Fermilab’s particle accelerator have confirmed the observation of an entirely new particle — the the Xi-sub-b baryon.


Baryons are particles formed of three quarks, in different configurations. The proton is a baryon that consists of two up and one down quark, and the neutron is two down and one up. The Xi-sub-b has an up quark, a strange quark (yes, that’s its real name) and a heavy bottom quark (again, real name), meaning that it weighs around six times as much as a proton or neutron.

Its existence has been predicted for some time, but hadn’t previously been observed. It doesn’t stick around long, though — traveling a fraction of a millimeter before decaying into lighter particles.

Happily, Fermilab has smashed together almost 500 trillion sets of particles, so researchers were able to verify the particle’s existence multiple times over. The Xi-sub-b has been spotted 25 times.

Fermilab’s Tevatron, where the Xi-sub-b was discovered, is based in Illinois in the United States, and was the highest-energy particle accelerator in the world until the Large Hadron Collider opened below Geneva.

Source: Wired

The First Self-Powering Nano-Device That Can Also Transmit Wireless Data

Scientists working with DARPA and Department of Energy backing have cracked the code on a kind of technological milestone, for the first time developing a nano-device capable of powering itself by harvesting energy from vibrations while at the same time transmitting data wirelessly over long distances. That kind of technology could have huge implications for devices ranging from surveillance implements to airborne sensors to implantable medical devices.

Publishing their findings in the journal ACS Nano Letters, the team describes a nanogenerator that turns mechanical vibrations scavenged from anything from a person’s pulse to a breeze to a person walking or cars driving over a bridge into electricity to power the device. That in and of itself isn’t so impressive, as such vibration-driven generators already existed previously.

The game-changer here is the fact that this nano-device can generate and store (in a capacitor) enough energy to also transmit wireless signals to a receiver up to 30 feet away via a transmitter roughly equivalent to those in Bluetooth headsets. The idea that something so small might be able to transmit data across distances could lead to new generations of medical sensors powered by a person’s own blood flow, environmental sensors powered by the ebb and flow of atmospheric air, and wearable sensors that run and transmit on the power leftover by the wearer’s own footsteps.

Source: Popsci via ScienceDaily

Researchers Build the First Living Laser, Using Human Cells and Jellyfish Protein

Researchers at Harvard Medical School and Massachusetts General Hospital built a living laser partly to study interactions between electronic and biological systems, and partly out of sheer curiosity. The world’s first biological laser, made from a single living cell, could lead to better microscope imaging inside the body and even targeted light therapies, researchers say.

A single human cell engineered to express green fluorescent protein can be used to amplify photons into super-short pulses of laser light, the researchers say.

Lasers consist of a gain medium, the source of optical gain within the laser which absorbs external energy and excites atoms or molecules into a more energized state, inside an optical cavity. Most lasers use semiconductors, crystals or gases as a gain medium. In this case, the researchers used green fluorescent protein (GFP).

First, the researchers filled an inch-long cylinder with a GFP solution, and placed mirrors at each end. They pulsed it with light and confirmed the GFP solution could amplify the input energy into short pulses of laser emissions, according to anews release from Mass. General. This proved GFP could serve as the laser’s gain medium. Green fluorescent protein, isolated from jellyfish, will emit green light when it is exposed to blue light.

Then the team engineered human embryonic kidney cells to produce GFP, and placed a single cell between two mirrors, just 20 micrometers apart. The researchers flooded the cell with blue light, and the cell lit up. The mirrors served as the optical cavity, allowing light to bounce through the cell many times, amplifying it into a coherent green beam that was visible to the naked eye.

Living Laser Schematic: When a single biological cell genetically programmed to produce green fluorescent protein is placed inside an optical resonator consisting of two parallel mirrors separated by 20 µm (0.02 mm), the cell can generate green laser light.  Nature Photonics/Malte Gather, Wellman Center for Photomedicine, Massachusetts General Hospital

The cell’s spherical shape acted as a lens, refocusing the light and therefore requiring less energy for lasing than was necessary in the cylinder experiment. Best of all, the cells survived the lasing process, and were able to produce hundreds of pulses of laser light.

A living laser could have a wide range of medical uses, according to lead author Malte Gather at the Wellman Center for Photomedicine at Mass. General. They could be used to activate drugs using light, for instance, or for new forms of imaging — it is difficult for visible and UV light to penetrate very far inside the body. Eventually, living lasers could enable optical communications and computing inside the body, using living systems instead of electronics.

Sourcs: Popsci,Eurekalert, BBC

First 'practical nanogenerator' developed

Tiny devices that turn bodily movements — such as the snap of one's fingers — into electricity for a cellphone or MP3 player are now much closer to making the leap from the laboratory into everyday life.

Called nanogenerators, these devices are made of so-called piezoelectric materials that generate a current of electricity when stretched or strained. So far, however, nanogenerators have not been able to crank out enough power to be useful.

Now, researchers have boosted the voltage and power output of these tiny generators to the point where they can power electronic components, including a light-emitting diode and a liquid crystal display.

"In the past, our voltage was less than one volt, so we could not power anything," said lead researcher Zhong Lin Wang, a professor at the Georgia Institute of Technology. "But now we can achieve three volts or even as high as five to 10 volts so that we can store the generated charge and use it to power those small devices."

The nano-scale chargers could be ready for commercial use in five years, Wang said.

Some applications include putting the chargers in the sole of a shoe to generate electricity from foot movement. The little power plants could also go in clothing and other fabrics, such as window curtains, or even under train rails to generate large amounts of electricity from train vibrations. Still other uses include insulin pumps implanted in the body and powered by a heartbeat as well as environmental sensors that get their juice from nanogenerators bending in the breeze.

The new nanogenerator is about the size of a fingertip and consists of a sheet of plastic with embedded rows of zinc oxide wires. By using a gold electrode, the researchers integrated thousands of the zinc oxide wires in such a way that their voltage was combined.

This arrangement boosted the device’s power output by three orders of magnitude and its voltage 150 times compared to a device made a year ago. And by stacking five plastic sheets together, the researchers were able to produce one microampere output current at three volts, which is the equivalent of the power of two regular AA batteries.

Wang and his team detail their findings today (Mar. 29) at the American Chemical Society's National Meeting and Exposition in Anaheim, Calif.

Source: TechNewsDaily