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11.13.2012

lightest metal on earth

Its called microlattice. Material was developed by scientists at UC Irvine and Caltech. It is lighter than styrofoam and as shown in the picture above can sit atop a dandelion without crushing it. From Popular Science:

The key structural component is a series of hollow tubes. In a study published last November in Science, the researchers exposed a light sensitive liquid to UV light through a patterned mask, which created a three-dimensional photopolymer lattice. They then deposited a layer of nickel-phosphorous onto the polymer lattice, which was then etched. The remaining structure was a macroscopic material with hollow tubes as the base structural elements. The resulting material had a density of .9 mg/cm3. By comparison, ultralight silica aerogels are 1 mg/cm3.

Though metallic microlattice is the lightest metal developed to date, it held the title of lightest material for less than a year. Aerographite, a carbon material developed by researchers at the Technical University of Hamburg and University of Kiel (and first reported in an Advanced Materials article in June 2012), weighs in at just .2 mg/cm3.

11.09.2012

continuous motion

Researchers at Brandeis have made a gel of microtubles and adding polymers to create a constantly moving material. From Scientific American:

The researchers first made a gel comprising microtubules — stiff polymer filaments that, in living cells, act as guiding tracks for kinesin, a ‘motor protein’ that is propelled along the microtubule cables by the cellular fuel ATP. “It’s like a tyre,” says Zvonimir Dogic, a physicist at Brandeis University in Waltham, Massachusetts, who led the study. Adding a small polymer to the mix encouraged the microtubules to form bundles and create a moving network. Water droplets containing this gel move continuously — in an oil emulsion and on flat surfaces — without external force, the researchers found.

Each molecule of ATP propels a kinesin molecule 8 nanometers forward along the microtubule track. With thousands of kinesins rumbling along multiple microtubules, a droplet that is 100 micrometers across spontaneously begins rolling when it touches a flat surface.

Check the Scientific American link for videos of the material in motion. The research appears in Nature.

08.31.2012

cyborg skin

Some Harvard & MIT scientists have developed a 3-D material that can act as a scaffold for human tissues. This material will allow tissues to grow and be able to monitor and report on the tissue’s health. Scientists are hoping it will help in development of new prosthetic devices. From PopSci:

[S]cientists led by MIT professor Robert Langer and Harvard chemistry professor Charles Lieber set out to build a 3-D scaffold that more closely resembles real tissue. The team wanted to build sensors that would let them monitor how the tissue responds to drugs in real time.

The scaffold is made from epoxy embedded with silicon nanowires, which can carry electrical signals to and from the cells. The mesh was folded or rolled into a structure resembling either tissue or vasculature. The nanowires can detect voltages lower than one-thousandth of a watt, according to MIT News — that’s the level of electricity that might be seen in a cell. The mesh was porous enough for the team to seed it with cells and coax them to grow. The system thereby supports cell growth while simultaneously monitoring it.

In their study, the authors used the scaffold to grow cardiac, neural and muscle tissue. They monitored heart tissue cell’s response to a stimulant called noradrenalin, which increases heart rate. Langer, who has published several groundbreaking studies on artificial tissue, nanowires and heart cells, said this could be a step toward engineered muscle: “It brings us one step closer to someday creating a tissue-engineered heart, and it shows how novel nanomaterials can play a role in this field,” he said.

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