Tag Archives: Technology

Researchers Developed New Efficient, Thin, and Flexible Cooling Device

Engineers and scientists from the UCLA Henry Samueli School of Engineering and Applied Science and SRI International, California, have created a thin flexible device that could keep smartphones and laptop computers cool and prevent overheating. The component is based on the electrocaloric effect – a phenomenon where the temperature of material changes when an electric field is applied to it. The research has been published in Science.

Thin, flexible cooling device
Thin, flexible cooling device

The system’s flexibility also allows it to be used in wearable electronics, robotic systems, and new types of personalized cooling systems. It is the first demonstration of a solid-state cooling device based on the electrocaloric effect. The method devised by UCLA and SRI researchers is very energy-efficient. It uses a thin polymer film that transfers heat from the heat source – a battery or a processor – to a heat sink, and alternates contact between the two by switching on and off the electric voltage.

Because the polymer film is very flexible, the system can be used in devices with complex shapes or moving surfaces. Body tracking wearable devices can easily accommodate this flexible cooling device. Such cooling pad could keep a person comfortable in a hot office and thus lower the electricity consumption for air conditioning. Or it could be placed in a shoe to keep a runner comfortable while running in the sun. It’s like a personal air conditioner.

The tendency of flexible electronics to overheat remains a major challenge for engineers. The cooling systems in larger devices like air conditioners and refrigerators, which use vapor compression, are just too large for mobile electronics. The new cooling device produces a specific cooling power of 2.8 watts per gram and a COP of 13. This is more efficient and compact than the existing surface-mountable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.

Roy Kornbluh, an SRI research engineer, said,

The development of practical efficient cooling systems that do not use chemical coolants that are potent greenhouse gases is becoming even more important as developing nations increase their use of air conditioning.

Researchers Developed Highly Durable Washable And Stretchable Solar Cells

Scientists of Japanese research institute RIKEN and the University of Tokyo have successfully developed a product that allows solar cells to continue to provide solar power after being washed, stretched and compressed. Takao Someya of Riken Center for Emergent Matter Science, a designated national R&D Institute in Japan, led the research team.

Washable and stretchable solar cell
Washable and stretchable solar cell

The research results were published in the journal Nature Energy and illustrated a photovoltaic material that could be used to make washable outer garments and wearable devices. The researchers say that the innovated solar cells will be a power source to low-power devices and can also be worn concurrently. This innovation might solve one of the biggest challenges of the Internet of Things (IoT), the requirement of a reliable power source to keep all devices connected.

The newly invented solar cells could power wearable devices that include health monitors and sensors for analyzing the heartbeat and body temperature. This could make prevention and early detection of potential medical problems possible. Though the concept of wearable solar cells is not unique, the previous wearable solar cell solutions suffered from the lack of one vital property i.e. long-term stability in air and water, including resistance to deformation.

The recent stretchable solar cell innovation has successfully achieved all of the most important features and is creating the way for the top-notch quality of modern wearable technology. The material on which their new device is based on is called PNTZ4T – a highly efficient polymer solar cell capable of small photon energy loss. The scientists deposited the device onto a parylene film which was then placed onto an acrylic-based elastomer. The construction method has proved to be particularly very durable.

The device produced 7.86 milliwatts per square meter based on a sunlight simulation of 100 milliwatts per square meter before considering resistance and durability. It showed the least decrease in efficiency when soaked in the water and when stretched. The efficiency decreased by only 5.4 percent and 20 percent respectively. Kenjiro Fukuda of RIKEN Center for Emergent Matter Science said,

We were very gratified to find that our device has great environmental stability while simultaneously having a good efficiency and mechanical robustness. We very much hope that these washable, lightweight and stretchable organic photovoltaic will open a new avenue for use as a long-term power source system for wearable sensors and other devices.

Researchers Develop Long Range Backscatter Sensors That Consume Almost No Power

Researchers at the University of Washington developed a new backscatter sensors that can operate over long ranges with very little power. The researchers demonstrated for the first time that the device runs on almost zero power and can transmit data across distances of up to 2.8 kilometers.

The long-range backscatter system developed by UW researchers
The long-range backscatter system developed by UW researchers

Backscatter communication works by emitting a radio signal and then monitoring the reflections of that signal from sensors. As the transmitter generates the signal, the sensors themselves require very little power. But this kind of system badly suffers from noise. Noise can be added anywhere – on the transmitter side, on the channel or on the sensor array. The key to solving this problem is a new type of signal modulation called chirp spread spectrum.

By using the chirp spread spectrum modulation technique, the team was able to transmit data up to 2.8 kilometers while the sensors themselves consumed only a few microwatts of power. Such extremely low power consumption lets them run by harvested ambient energy and very small printed batteries. The cost is surprisingly cheap too. The sensors would cost just 10 to 20 cents per unit if bulk purchased.

Today’s flexible electronics and other sensors need to operate with very low power typically can’t communicate with other devices more than a few feet or meters away. By contrast, the University of Washinton’s long-range backscatter system achieved pretty strong coverage throughout a 4800-square-foot house, an office area including 41 rooms, and a one-acre vegetable farm at extremely low power and low cost.

Shyam Gollakota, the lead faculty and associate professor in the Paul G. Allen School of Computer Science & Engineering, said,

Until now, devices that can communicate over long distances have consumed a lot of power. The tradeoff in a low-power device that consumes microwatts of power is that its communication range is short. Now we’ve shown that we can offer both, which will be pretty game-changing for a lot of different industries and applications.

These low-power sensors have endless potential applications. They can be used for everything from wearable health monitors to scientific data collection devices. Though there are no confirmed products yet, the team has created few prototypes in the form of flexible sensors worn on the skin, smart contact lenses, and more.

iEAT – A Powerful Keychain Detector To Detect Food Allergens

For kids and adults with food allergies, having meals from restaurants or hotels can sometimes be very risky. Even when ultimate care is taken, freshly prepared meals can accidentally become cross-contaminated with an offending food and trigger an allergic reaction. Every year many people end up in the emergency room due to food allergies. Researchers of the Harvard Medical School developed an affordable device called iEAT for detecting allergens, which can reduce the anxiety of the people prone to allergies.

iEAT - A Portable allergen-detection system
iEAT – A Portable allergen-detection system

Conventional methods to detect the hidden allergens require massive laboratory equipment. They are slow and also do not work on a low concentration of allergens. Ralph Weissleder, Hakho Lee, and their colleagues at the Harvard Medical School wanted to make a more practical, consumer-friendly alternative. They reported in the journal ACS Nano the development of a new portable allergen-detection system that features a keychain analyzer for detecting allergens in food anywhere, anytime.

The portable allergen-detection system called integrated exogenous antigen testing or iEAT is small enough to fit in your pocket and it costs $40 only. The iEAT consists of a handheld device to extract allergens from food and an electronic keychain reader for sensing allergens. Then, the result is wirelessly sent to a smartphone. The prototype is able to detect five allergens within 10 minutes, one each from wheat, peanuts, hazelnuts, milk, and egg whites, even if they are in very low concentration.

The main device uses a disposable sample collector which is inserted into the small-sized main unit. The device is so sensitive that the scientists were able to detect gluten in foods advertised as being “gluten-free”. For example, the device detected gluten in salad and an egg protein in beer. Although the prototype was primarily designed to sense five allergens only, the researchers say the device could be expanded to test for many additional compounds, including other allergens and non-food contaminants such as pesticides.

Terahertz Electronics – Way To Bridge The largely-untapped Region Between 100GHz and 10THz

The terahertz (THz) region, which is based on 1THz frequency, separates electronics from photonics and has been difficult to access for ages. Semiconductor electronics cannot handle frequencies equal to or greater than 100GHz due to various transport-time related limitations. In other hand, photonics devices fail to work below 10THz as photon’s energy significantly drops to thermal energy. Terahertz Electronics (TE) is a new technology that extends the range of electronics into the THz-frequency region.

The Terahertz Gap
The Terahertz Gap

The main goal of Terahertz Electronics is to build a bridge between low-frequency “Electronics” and high-frequency “Photonics”. Since these devices use photon-electron particle interactions, as photon energy “hv” decreases below thermal energy “kT”, the device ceases to operate efficiently unless it is cooled down. At the low-frequency end, electronics cannot operate above 100GHz as transport time is dependent on drift and diffusion speeds of electrons/holes. As a result, a large region between 100GHz and 10THz remained inaccessible. Terahertz Electronics solves this problem efficiently by cleverly incorporating electronics with photonics.

Terahertz electronics technology offers practical applications in high-speed data transfer, THz imaging, and highly-integrated radar and communication systems. Surprisingly enough, It does not use semiconductors. Instead, it is based on metal-insulator tunneling structures to form diodes for detectors and ultra-high-speed transistors for oscillator based transmitters.

One drawback of the Terahertz Electronics is, it requires high-frequency radiation sources. Lack of a small, low-cost, moderate-power THz source is one of the main reasons that THz applications have not fully materialized yet. Scientists are trying to find a solution to this problem. They created a compact device that can lead to portable, battery-operated sources of THz radiation. This new solid-state T-ray source uses high-temperature superconducting crystals that contain stacks of Josephson junctions. So, even a small voltage, around two millivolts per junction, can induce frequencies in the THz range.

Mercury arc lamps generate light in terahertz
Mercury arc lamps generate light in terahertz

TE devices are extremely fast and they are made entirely of thin-film materials—metals and insulator. Hence, it is possible to fabricate Terahertz Electronics devices on top of complementary metal oxide semiconductor (CMOS) circuitry—a technology for creating integrated-circuits circuitry or on an extensive variety of substrate materials. In TE devices, charge transport through the junction occurs via electron tunneling. Further research and development will make Terahertz Electronics a reality in not-so-distant future.

Next Generation Solar Cell That Can Capture Nearly All Energy of Solar Spectrum

Researchers developed a multijunction solar cell on a GaSb substrate that can efficiently convert the long-wavelength photons typically lost in a multijunction solar cell into electricity. This prototype cell has an efficiency of 44.5% which is higher than conventional solar cells.

Next Generation Solar Cell To Absorb Nearly All Solar Spectrum
Next Generation Solar Cell To Absorb Nearly All Solar Spectrum

A GaAs-based cell is stacked mechanically with the GaSb-based materials to create a four-terminal, five junction cell with a spectral response range covering the region containing greater than 99% of the available direct-beam power from the Sun reaching the surface of the Earth. By comparison, the most typical solar cell can convert only one fourth of the available energy into electricity.

The working principle of this new solar cell is slightly different than the commonly available one. The cell is assembled in a mini-module that has a lens with a geometric concentration ratio of 744 suns. The lenses to concentrate sunlight onto tiny, microscale solar cells. As the solar cells have a very tiny form factor of  1 mm², solar cells using more complicated materials can be developed cost effectively.

The stacked cell acts like a filter with a particular material in each layer to absorb a specific range of wavelength of sunlight. The stacking procedure uses the transfer-printing technique which enables three dimensional modeling of these super-tiny devices with a high degree of precision.

Around 99 percent of the power contained in direct sunlight reaching the surface of Earth falls between wavelengths of 250 nm and 2500 nm. The entire range is not accessible by conventional solar panels as they are made from abundant, cheaper materials, such as silicon. Matthew Lumb, the lead author of the study and a research scientist at the GW School of Engineering and Applied Science, said,

Our new device is able to unlock the energy stored in the long-wavelength photons, which are lost in conventional solar cells, and therefore provides a pathway to realizing the ultimate multi-junction solar cell.

The cost of this specific solar cell is pretty high due to the high-end materials used and complex technologies implemented. However, the researchers achieved the upper limit of possibility in terms of efficiency. The new solar cell shows much promise in spite of being highly expensive. perhaps in future, the production cost can be reduced and the similar solar cell will be available commercially in the market.

IBM scientists achieve storage memory breakthrough

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For the first time, scientists at IBM Research have demonstrated reliably storing 3 bits of data per cell using a relatively new memory technology known as phase-change memory (PCM).

The current memory landscape spans from venerable DRAM to hard disk drives to ubiquitous flash. But in the last several years PCM has attracted the industry’s attention as a potential universal memory technology based on its combination of read/write speed, endurance, non-volatility and density. For example, PCM doesn’t lose data when powered off, unlike DRAM, and the technology can endure at least 10 million write cycles, compared to an average flash USB stick, which tops out at 3,000 write cycles.

IBM scientists achieve storage memory breakthrough – [Link]