System Bits: March 8

Living, breathing supercomputers
Adenosine triphosphate (ATP), the substance that provides energy to all the cells in the human body, may also be able to power the next generation of supercomputers, according to McGill University researchers.

The team has described a model of a biological computer that they have created that is able to process information very quickly and accurately using parallel networks in the same way that massive electronic super computers do — except that the model bio supercomputer they have created is a whole lot smaller than current supercomputers, uses much less energy, and uses proteins present in all living cells to function. 

The model bio-supercomputer that the researchers created came about thanks to a combination of geometrical modeling and engineering know-how on the nano scale. It is a first step in showing that this kind of biological supercomputer can actually work.

The circuit looks a bit like a road map of a busy and very organized city as seen from a plane. Just as in a city, cars and trucks of different sizes, powered by motors of different kinds, navigate through channels that have been created for them, consuming the fuel they need to keep moving. But in the case of the biocomputer, the city is a chip measuring about 1.5 cm square in which channels have been etched. Instead of the electrons that are propelled by an electrical charge and move around within a traditional microchip, short strings of proteins (which the researchers call biological agents) travel around the circuit in a controlled way, their movements powered by ATP, the chemical that is, in some ways, the juice of life for everything from plants to politicians, they explained.

And because it is run by biological agents, it hardly heats up at all, and therefore uses far less energy than standard electronic supercomputers do, making it more sustainable. Traditional supercomputers use so much electricity that they heat up a lot and then need to be cooled down, often requiring their own power plant to function, the researchers reminded.

Clear graphene light detectors enable better 3D cameras
With the eventual goal of enabling virtual reality, University of Michigan researchers are developing a camera that can record 3D images and video in a small form factor than others currently on the market, and achieve higher resolutions.

Today, 3D cameras are useful for a variety of applications including 3D movie filming and, eventually, virtual reality. While 3D films are currently made using multiple cameras to reconstruct each frame, this new type of camera could record in 3D on its own, the researchers said.

An illustration showing how a new 3D camera will be designed to work. Here, it takes a 3D photo of a University of Michigan solar car. In this new method, objects at different distances from the lens will come into focus at different points inside the camera.
(Source: Michigan Engineering)

Images and video recorded by 3D cameras might one day be projected as holograms, but projection is a different challenge: In photography, 3D images enable users to decide the depth of focus after taking the photograph. Attached to microscopes, a 3D camera can image cells and tissues for more accurate analysis of biopsies and medical cultures, as well as for fundamental research. 3D video recording could give robots depth perception and eventually lead to a bionic eye. When the light hits the detector inside a camera, it can come from different directions, and this spatial information can be used to reconstruct 3D images. Normally, that information is lost because the detector only measures intensity, which is why 3D images made with traditional recording methods must be constructed from multiple shots.

One-shot 3D cameras currently available use a micro-lens array to divert the light after it has been focused by the main lens. This array of smaller lenses essentially tears up the picture to recover the directional information from the rays of light, and then the camera’s software reconstructs the image along with the depth information.

This new design does away with the micro-lens array and instead, the camera records the light as it passes through a series of transparent light detectors.

Flexible, transparent pressure sensor
In an advancement that may one day allow healthcare practitioners to physically screen for breast cancer using pressure-sensitive rubber gloves to detect tumors, University of Tokyo researchers working with American colleagues have developed a transparent, bendable and sensitive pressure sensor.

They explained that conventional pressure sensors are flexible enough to fit to soft surfaces such as human skin, but they cannot measure pressure changes accurately once they are twisted or wrinkled, making them unsuitable for use on complex and moving surfaces. It is also difficult to reduce them below 100 micrometers thickness because of limitations in current production methods.

To address these issues, an international team of researchers led by Dr. Sungwon Lee and Professor Takao Someya of the University of Tokyo’s Graduate School of Engineering has developed a nanofiber-type pressure sensor that can measure pressure distribution of rounded surfaces such as an inflated balloon　and maintain its sensing accuracy even when bent over a radius of 80 micrometers, equivalent to just twice the width of a human hair. The sensor is roughly 8 micrometers thick and can measure the pressure in 144 locations at once.

The device demonstrated in this study consists of organic transistors, electronic switches made from carbon and oxygen based organic materials, and a pressure sensitive nanofiber structure. Carbon nanotubes and graphene were added to an elastic polymer to create nanofibers with a diameter of 300 to 700nm, which were then entangled with each other to form a transparent, thin and light porous structure.

They’ve also tested the performance of the pressure sensor with an artificial blood vessel and found that it could detect small pressure changes and speed of pressure propagation.

The pressure sensors wraps around and conforms to the shape of the fingers while still accurately measuring pressure distribution.
(Source: University of Tokyo)