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Friday, August 12, 2011

New artificial lung breathes like a real one

By Stacy Lipson

Researchers from the Department of Veterans Affairs Medical Center and Case Western Reserve University in Cleveland have invented an artificial lung that breathes regular air instead of purified oxygen.

I spoke with Joseph Potkay, the study author whose research on the artificial lung appeared in the journal Lab on a Chip. Below is an excerpt of our conversation.

How does the artificial lung work?

The artificial lung works just like the natural lung - it adds oxygen to and removes carbon dioxide from the blood. It does this in the same way that the natural lung does as well. Inside the artificial lung, blood and air are separated by a very thin membrane. This membrane allows gas - oxygen and carbon dioxide - to freely pass through it by the process of diffusion. Due to a difference in partial pressure, oxygen flows from the air through the membrane and into blood, enriching it. For carbon dioxide, the process is reversed.

What is it made out of?

The artificial lung is made completely out of silicone rubber, otherwise known as polydimethylsiloxane or PDMS. It is formed using microfabrication and micromolding techniques.

How is this different from previous technologies?

In this work we have utilized microtechnology to produce artificial capillaries and a membrane that exhibit feature sizes that are very close to those found in the natural lung. These small features result in very small diffusion distances which result in a high gas exchange efficiency. This high efficiency has enabled us to use air to ventilate the artificial lung. Previous technologies have required pure oxygen due to their inefficiency. Thus, in essence, this technology eliminates the need for bulky pure oxygen gas cylinders and is a step towards truly portable and implantable artificial lungs.

What is it modeled after? What parts are used?

The device is designed to roughly mimic the natural lung. It contains artificial vessels, capillaries, and aveoli that are similar in size to those found in the natural lung.

How can this match a regular human lung?

There are two main areas of improvement that are needed before this technology can match the impressive human lung. First, we must scale the device up in size to be able to support larger blood flow and gas exchange rates. Second, we must improve the biocompatibility of the device so that it will have a longer lifetime when interfacing with the body. Even so, in the near term, we expect that the resulting technology will be utilized for short-term rehabilitation from lung disease or as a bridge to transplant.

Why is this artificial lung more efficient than previous technologies?

This artificial lung is more efficient than previous technologies due to its small feature sizes and, thus, small gas diffusion distances.

What tests have been done on the artificial lung?

Thus far, the gas exchange performance of the artificial lung has been tested in the laboratory using pig blood. We hope to scale up the device in size to be able to provide respiratory support to small animals in the next couple years.

What do you hope will come from your research? How will this effect lung disease in the future?

We hope that this technology will be used in portable artificial lung systems to treat patients suffering from acute and chronic lung failure. We hope it will not only save lives, but also improve the quality of life for patients requiring treatment with an artificial lung device. Due to gas exchange and size limitations, current artificial lung patients are virtually immobile.

When do you hope to have human scaled artificial lungs available to the public?

We hope to begin animal tests in a couple of years and human trials in eight to ten years.

Image: via Case Western Reserve University

Printable paper solar panels can power gadgets

By Tuan C. Nguyen |

A new manufacturing technique may allow for solar panels to be produced simply using nothing more than an ink-jet printer.

The new technique, developed by MIT researchers, is a much gentler technology than what’s being used to manufacture solar cells. That’s because the process involves using vapors instead of liquid to bring down the temperature during manufacturing to less than 120 degrees Celsius, which allows it to be used on more delicate materials like paper, cloth or plastic.

The idea behind the MIT team’s approach is that if researchers can perfect a process in which cells can be printed on common everyday materials like cloth and paper, you would suddenly open the technology up to all kinds of possibilities for household use. Cells can be painted on wallpaper or companies can produce solar-powered curtains to harness energy anywhere the sun might shine.

The cells, which are quite durable, can be scrunched up, made into a paper airplane or even folded a thousand times over and still deliver solid performance. And if you wanted to harness energy outdoors, the paper can be laminated to protect it from harsh weather conditions.

Versatile and affordable solar cells would be a major boon to the industry. High manufacturing costs is one of the reasons why solar power hasn’t hit the mainstream as some renewable energyadvocated had hoped. For instance, the glass that supports the active photovoltaic material coupled with installation can cost twice as much as the cells themselves. In contrast, paper costs one-thousandth as much as glass for a given area, according to the researchers.

The drawback is that paper-printed solar cells have an efficiency of about 1 percent, though researchers believe this can be improved significantly with further fine-tuning of the materials. Still, researchers say the amount of energy is supplied is “good enough to power a small electric gizmo.”

“We have demonstrated quite thoroughly the robustness of this technology,” says Vladimir Bulović, a professor of electrical engineering. “We think we can fabricate scalable solar cells that can reach record-high watts-per-kilogram performance.”

Image: MIT

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Breakthrough could lead to 732-mile electric car battery

By Tuan C. Nguyen |

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Although it’s difficult to pinpoint what exactly it would take to alleviate electric car “range anxiety,” but I’ll go out on a limb and say that for the vast majority of people, oh, 732 miles on a charge would more than suffice.

While such a technology doesn’t exist, Japanese researchers at Sumitomo Electric have come up with a breakthrough that could triple the energy capacity of lithium-ion batteries, and in effect make it a very real possibility. It’s called Aluminum-Celmet, a 98 percent porous material that, when used in place of a standard aluminum foil anode, allows for electric car batteries to be packed with a lot more lithium.

Aluminum-Celmet is similar to nickel Celmet, a material that can be found in nickel-cadmium and nickel-metal hydride batteries. Both are produced using a process that involves applying an electro conductive coating to plastic foam, followed by nickel plating. The resulting material then undergoes heat treatment to remove the plastic foam, leaving behind something resembling a mesh fabric, but in metallic form. However, the difference is that Aluminum-Celmet is lighter, has better electrical conductivity and the kind of corrosion resistance necessary to hold up to the rigors that electric cars are put through each day.

The degree in which Celmet anodes may improve battery capacity is exponential. According to a company statement, the material could “increase battery capacity 1.5 to 3 times. Alternatively, with no change in capacity, battery volume can be reduced to one-third to two-thirds. These changes afford such benefits as reduced footprint of home-use storage batteries for power generated bysolar and other natural sources, as well as by fuel cells.”

That means the range of a Tesla Roadster, which has the top rated per charge distance, could be boosted to about 732 miles. Even the Nissan Leaf would suddenly be a lot more appealing if it was capable of going 219 miles, instead of the standard anxiety-inducing 73 miles per charge.

While this latest development is promising, Sumitomo Electric hasn’t provided any sort of timeline of when they expect to scale up the technology for automotive markets. All the company is willing to say at this point is that it will continue to improve Aluminum-Celmet for commercial use in lithium-ion battery and capacitors. A good sign is that the company has set up a small-scale production line at Osaka Works in preparation for the manufacturing phase.

But if I had to take a gander, I’d say it might be a while — that is if it ever does happen.

(via press release)

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