Science category

InGaAs TFET, a potential alternative to MOSFET in future ultralow power chips

by Graham Prophet @ edn-europe.com:

Belgian researchers from imec, at a conference** dedicated to compound semiconductor technology, are to present promising device results with a InGaAs-only TFET (tunnel field-effect transistor) that achieves a sub-60 mV/decade sub-threshold swing at room temperature.

The New Light-responsive Nano LEDs

A team of researchers from the US and South Korea reported a unique type of NanoLEDs with unprecedented brightness levels, that excess 80,000 cd/m2, and also can operate both as light emitters and light detectors.

These new LEDs are about 50nm long and 6nm in diameter. As described in the paper, they included quantum dots of two different types, one of which can enhance radiative re-combinations (useful for LEDs) while the other type leads to efficient separation of photo-generated carriers.

Low- and high magnification scanning transmission electron microscopy images of DHNRs (right) magnified image of the region within the white dotted box on the left.

The research of this invention had been published in a paper titled “Double-heterojunction nanorod light-responsive LEDs for display applications“. The researchers consider the dual-mode LEDs will pave the way to new types of interactive displays.

As we head toward the “Internet of things” in which everything is integrated and connected, we need to develop the multi-functional technology that will make this happen. Oh et al. developed a quantum dot-based device that can harvest and generate light and process information. Their design is based on a double-hetero-junction nano-rod structure that, when appropriately biased, can function as a light-emitting diode or a photodetector. Such a dual-function device should contribute to the development of intelligent displays for networks of autonomous sensors.

The device can reach a maximum brightness in excess of 80,000 cd/m2 with a low turn-on voltage (around 1.7 V). It also exhibits low bias and high efficiencies at display-relevant brightness. The research team reports an external quantum efficiency of 8.0% at 1000 cd/m2 under 2.5 V bias.

Energy band diagram of DHNR-LED along with directions of charge flow for light emission (orange arrows) and detection (blue arrows) and a schematic of a DHNR.

One of the experiments was operating a 10×10 pixel DNHR-LED array under reverse bias as a live photodetectors, combined with a circuit board that supplied a forward bias to any pixel detecting incident light. And by alternating forward and reverse bias at a sub-millisecond time scale, light-detecting pixels could be “read out” as they illuminated the array.

Future applications of the DNHR LEDs include:

  • Translate any detected signal into brightness adjustments;
  • Automatic brightness adjustment in response to external light–intensity change;
  • Direct imaging or scanning at screen level;
  • Display-to-display data communication.
  • Displays can harvest or scavenge energy from ambient light sources without the need for integrating separate solar cells.

Sources: elektor, EETimes

Super cheap ‘lab-on-a-chip’

by Eric Bogers @ elektormagazine.com:

Researchers from the Stanford University School of Medicine, using a combination of microfluidics, electronics and a standard inkjet printer, have succeeded in producing a biochip that can be used for research or diagnostic purposes. The remarkable feature of this new ‘lab-on-a-chip’ is the cost: less than one cent each.

Super cheap ‘lab-on-a-chip’ – [Link]

Better current with spin electronics

by Clemens Valens @ elektormagazine.com

The ongoing miniaturisation of electronics is expected to reach its limits in the near future. One of the limitations is the size of electrons that are needed in electronic circuits to transport charge from one place to the other, what we usually call ‘current’. To work around this problem a team of scientists from Munich and Kyoto proposes a way to make current “better”, by using the electron’s spin instead of its charge. Enter spin electronics.

Better current with spin electronics – [Link]

facetVISION camera

facetVISION: Compound Eyes for Industry and Smartphone

Researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF have developed a process that makes the production of a two-millimeter flat camera possible. Similar to the eyes of insects, its lens is partitioned into 135 tiny facets. The researchers have named their mini-camera concept facetVISION, following nature’s model. This mini-camera has a thickness of only two millimeters at a resolution of 1 megapixel.

facetVISION compound eye: First prototype
facetVISION compound eye: First prototype

All 135 small, uniform lenses are positioned close together, similar to the pieces of a mosaic. Each lens receives only a small section of its surroundings. The newly developed facetVISION technology aggregates the many individual images of the lenses to a whole picture. Finally, this technology should obtain a resolution of 4 megapixels. This is certainly a higher resolution compared to latest cameras in industrial applications like robot technology or automobile production.

The compound eye technology is also suitable for integration into smartphones. The lens of a modern smartphone must be at least 5 millimeters thick in order to capture a sharp image. The manufacturers of ultrathin smartphones are facing this challenge since the camera lens is thicker than the housing of the phone. But, this new technology can reduce the thickness to around 3 millimeters without compromising picture quality. Andreas Brückner, the project manager at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena, says:

It will be possible to place several smaller lenses next to each other in the smartphone camera. The combination of facet effect and proven injection molded lenses will enable resolutions of more than 10 megapixels in a camera requiring just a thickness of around three and a half millimeters.

The researchers also explained how this camera can be used in medical engineering as optical sensors to examine blood. The facetVISION has many other applications like checking image quality in a printing machine, parking camera in cars or in industrial robots to prevent collisions between human and machine.

Mass production of facetVISION is possible
Mass production of facetVISION is possible

Under the leadership of Andreas Brückner, the researchers have already demonstrated that facetVISION is suitable for mass production. So, keep waiting and maybe you will purchase a new smartphone equipped with a facetVISION compound eye in not so distant future.

Dosime Radiation Meter

Dosime Radiation Meter: Know The Radiation Surrounding You Using Smartphone

Radiation is always present in our lives. We can’t see, taste, feel or smell it, but it exists. Excessive exposure to ionizing radiation may cause potential damage to our health. The new Dosime device helps you to track and understand radiation exposure in your environment and display them using an app on your smartphone.

Dosime Radiation Meter For your Smart Phone
Dosime Radiation Meter For your Smart Phone
Pie Chart of Radiation Sources
Pie Chart of Radiation Sources

Dosime is a hybrid smart home and wearable device. The device weighs just 57 grams and is only 6.8 centimeters in height, making it extremely easy to take it with you everywhere. Now, the most important question is, how necessary is it to measure radiation level if someone is not living by a nuclear plant? Well, a nuclear plant is not the only one who emits radiation. 82% of the radiation we are exposed to comes from natural sources. The remaining 18% comes from man-made sources. So, yes. It is necessary to measure radiation level in your environment. On their website the company says:

Healthy living includes managing your environment, including factors you can not perceive. Knowledge of radiation exposure empowers you to make informed decisions about your wellbeing.

The Dosime radiation meter can measure radiation levels up to 100 R/h with a maximum dose of 1000 rem. The range of the measurable energy is 50 keV to 3 MeV. It can detect X-Rays and Gamma (γ) rays, but not Alpha (α) rays and Beta (ß) rays. Unfortunately, they are also sources of harmful ionizing radiation.

The Dosime device seamlessly connects to smartphones via WiFi and Bluetooth Low Energy (BLE). It comes with a built-in rechargeable battery and an AC/DC module. The battery lasts for about one week on a single charge. At home you can dock it in the charger, giving it access to the Wi-Fi network. The app for this device runs on iOS 9 or later, or Android KitKat 4.4 or later.

The Dosime device is available for purchase at a price of US $249.00 (+ $4.81 shipping). You can order it at Amazon.

Nuclear physics applied in smoke detectors

by robertgawron.blogspot.com:

Not many people know, but in some smoke detectors, radioactive materials play an essential role. Today I will present one of those devices, and my -successful- attempt to reverse engineer it and get the circuit diagram.

Nuclear physics applied in smoke detectors – [Link]

Human Motion Powered Nanotechnology Devices

Michigan State University researchers have came up with a new method for  harvesting energy from human motion using nanotechnology. They designed a low-cost film-like device, a nanogenerator, than can power a LCD display,  keyboard, and some LEDs without any source of electric power, by only using some human touching or pressing.

This device called FENG, biocompatible ferroelectret nanogenerator, consists of several thin layers of silicon wafer made of environmentally friendly substances like silver, polyimide, and polypropylene ferroelectret – which is introduced here as the active material of this device. To add the electrical powering feature, researchers added ions to each layer to make sure that each layer has its own charged particles. Finally the circuit works only once some pressure or mechanical energy is performed on the device. For example, by using this technology you will be able to power the LED lights with the pressure of your palm, while the pressure of your finger is enough to power the LCD screen.

In this video 20 LEDs are powered with hand pressing:

Researchers’ investigations had shown that the voltage and current generated by pressure can be doubled if the device is folded, means a high-frequency pressure is already demonstrated.

“Each time you fold it you are increasing exponentially the amount of voltage you are creating,” said Nelson Sepulveda, associate professor of electrical and computer engineering and lead investigator of the project. “You can start with a large device, but when you fold it once, and again, and again, it’s now much smaller and has more energy. Now it may be small enough to put in a specially made heel of your shoe so it creates power each time your heel strikes the ground.”

Sepulveda believes that implementing this technology in real life will shift wearables to be completely powered by human motion. He and his team are working now on transmitting the power generated from the heel strike to be used for powering other devices like a headset.

In this video you can take a look at the flexible keyboard they designed:

This research was funded by the National Science Foundation. You can learn more about this project by checking the scientific paper, and the university official website.

Supercapacitors Surpassing Conventional Batteries

Researchers at the University of Central Florida have been looking for alternatives for lithium rechargeable batteries which are largely used in every device.

Using two-dimensional (2D) transition-metal dichalcogenides (TMDs) capacitive materials, they are building a new supercapacitor that overcomes the performance of conventional lithium battery and replaces its efficiently.

Transition metal dichalcogenide monolayers (TMDs) are atomically thin semiconductors of the type MX₂, with M a transition metal atom and X a chalcogen atom. One layer of M atoms is sandwiched between two layers of X atoms.

TMDs are considered as promising capacitive materials for supercapacitor devices since they provide a suitable current conduction path and a robust large surface to increase the structure’s high energy and power density.

Researchers have developed “high-performance core/shell nanowire supercapacitors based on an array of one-dimensional (1D) nanowires seamlessly integrated with conformal 2D TMD layers. The 1D and 2D supercapacitor components possess “one-body” geometry with atomically sharp and structurally robust core/shell interfaces, as they were spontaneously converted from identical metal current collectors via sequential oxidation/sulfurization” according to the research paper.

The new prototype is said to be charged 30,000 times without any draining, 20 times the lifetime of an ordinary battery.

“You could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week,” says UCF postdoctoral associate Nitin Choudhary.

This research was published in the NANO science journal, you can check the scientific paper here.

New Thermoelectric Paint To Convert Heat Into Electricity

Scientists at the Ulsan National Institute of Science and Technology have developed a thermoelectric coating that can be directly painted onto any surface to turn it into thermal generator. This new technique can be used to convert waste heat into electricity from objects of almost any shape.

The team created an inorganic thermoelectric paint that possesses liquid-like properties using Bi2Te3 (bismuth telluride) and Sb2Te3 (antimony telluride) particles. These newly developed materials are both shape-engineerable and geometrically compatible so they can be directly brush-painted on almost any surface.

To test the new materials results, the researchers painted alternate p-type and n-type layers of the thermoelectric semiconductor paint on a metal dome, which generates about 4 mW output power per square centimeter.

Compared with some flexible thermoelectric generators, such as KAIST’s wearable device and Northwestern University’s thermoelectric material, the generated power of UNIST materials is just 10% of others, but the most important advantage is that it can be applied on any surface with just a paintbrush.

“By developing integral thermoelectric modules through painting process, we have overcome limitations of flat thermoelectric modules and are able to collect heat energy more efficiently.” said Professor Son of UNIST. “Thermoelectric generation systems can be developed as whatever types user want and cost from manufacturing systems can also be greatly reduced by conserving materials and simplifying processes.”

The UNIST researchers aim to see their invention as a renewable energy source, which will be possible to convert heat and cold to electricity by simply painting the external surfaces of buildings, on roofs, and on the exterior of cars, and open the way to many other materials and devices easily transferred to many other voltage-generation applications.

Comparison of power generation between the conventional planar-structured TE generator and the painted TE generator on a curved heat source.

“Our thermoelectric material can be applied any heat source regardless of its shape, type and size.” said Professor Son. “It will place itself as a new type of new and renewable energy generating system.”

To know more about the results and other information of this research, read its paper in the journal Nature Communications.

Sources: New Atlas, UNIST