Science category

Reliable molecular switch

by Eric Bogers @ elektormagazine.com:

Nanotechnology repeatedly breaks new records in the area of miniaturization. However, there are physical limits when reducing the size of electronic components and these will be reached in the near future. This means that new materials and components will be required – and it is here where molecular electronics will play a role. Researchers from the Karlsruher Institut für Technologie (KIT) have succeeded in developing a molecular toggle switch, which will not only remain in the selected position, but can also be switched as often as desired without any deformation taking place.

Reliable molecular switch – [Link]

Electrons Counter-Intuitive Movement

Our ‘common sense’ would say that when an object moves from point A to point B it necessarily has to also move through all the points between A and B. This is, however, not true for electrons in the quantum world, where these intuitive truths are not valid. Electrons can, for example appear on the first floor and then on the third floor – without ever putting a foot down on the second floor (insofar that electrons have feet, of course).

Exactly this counter-intuitive behavior has been observed by professor Hui Zhao and his colleagues in the Ultrafast Laser Lab of the University of Kansas. In the sample, which consists of three different, ultra thin layers, electrons move from the top layer to the bottom layer without ever having been observed in the middle layer. According to Zhao this efficient form of quantum electron transport could play a key role in so-called Van der Waals materials, which have their uses in solar panels and in electronics in general.

The sample that was the subject of the research comprises three layers of semiconductor materials (MoS2, WS2 and MoSe2), each with a thickness of less than 1 nm. These three materials react to light of different wavelengths (colors).

The researchers used a laser pulse with a duration of 100 femtoseconds to knock a few electrons from the topmost MoSe2 layer so that they were able to move freely. With a laser pulse of the correct color for the bottom MoS2 layer (which, thanks to the difference in path length of 0.3mm, arrives one picosecond later than the first pulse), the appearance of the electrons in the bottom layer could be demonstrated. It appeared that the electrons on average needed 1 ps to move from the top layer to the bottom layer.

With a third laser pulse the middle layer was monitored – but no electrons on their way from the top to the bottom were ever observed there. Apparently the electrons ‘jumped over’ the middle layer – a behavior that has also been confirmed through simulations by theoretical physicists at the University of Nebraska-Lincoln.

Source: Elektor

Send & Receive Radio With A Single Chip

Fitting transmit and receive capabilities of radio signals into one device may be impossible without using a significant filter, which is needed to isolate sent and received signals from each other.

The major obstacle to achieve that is the weakness of the received signal compared with the much stronger transmitted signal. However, researchers from Cornell University found their way to jump over this obstacle and created a two-way transceiver chip.

Alyosha Molnar, associate professor of electrical and computer engineering (ECE), and Alyssa Apsel, professor of ECE, had come up with a new solution to separate the signals. They made the transmitter consist of six sub-transmitters hooked into an artificial transmission line. Each one sends a weighted signal at regular intervals which combined with others such as a radio frequency signal in the forward direction, and at the same time they cancel each other in the opposite direction (towards to receiver).

The programmability of the individual outputs allows this simultaneous summation and cancellation to be tuned across a wide range of frequencies, and to adjust to signal strength at the antenna.

“You put the antenna at one end and the amplified signal goes out the antenna, and you put the receiver at the other end and that’s where the nulling happens,” Molnar said. “Your receiver sees the antenna through this wire, the transmission line, but it doesn’t see the transmit signal because it’s canceling itself out at that end.”

This research is based on a research reported six years ago by a group from Stanford University, which demonstrated a way for the transmitter to filter its own transmission, allowing the weaker incoming signal to be heard.

One of the sub-transmitter concept enhancements is that it will work over a range of frequencies, and instead of using a filter for every band, signal separation can be controlled digitally.

“You could have a single device that can be anything,” Apsel said. “You wouldn’t have to buy a new piece of equipment to have the newest version of it.”

You can find the full research at the IEEE Journal of Solid State Physics.

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]