nano Related Articles

(Random telegraph noise from single molecule was adsorbed on SWNT.) Noise is low-frequency random fluctuation that occurs in many systems, including electronics, environments, and organisms. Noise can obscure signals, so it is often removed from electronics and radio transmissions. The origin of noise in nanoscale electronics is currently of much interest, and devices that operate using noise have been proposed. Materials with a high surface-to-volume ratio are attractive for studying the noise produced by nanoscale electronics because they are very sensitive to changes of their surfaces. A representative material of this type is carbon nanotubes, which are rolled sheets of the graphene hexagonal network, which is only one carbon atom thick. A Japanese collaboration led by Osaka University has explored the ability of single molecules to affect the noise generated by carbon nanotube-based nanoscale electronic devices. The team fabricated simple devices consisting of a carbon nanotube bridging two electrodes. The devices were exposed to different large molecules, causing some to bind to the carbon nanotube surface. It was found that different molecules gave unique noise signals related to the properties of the molecules. The strength of the interaction between the carbon nanotubes and molecules was able to be predicted from the obtained noise signals. "The signal generated by the carbon nanotube device changed following the adsorption of specific single molecules," says first author Agung Setiadi. "This is because the adsorbed molecule generated a trap state in the carbon nanotube, which changed its conductance." What this means is that the carbon nanotube-based devices were so sensitive that the researchers were able to detect unique signature from single molecules. The ability to characterize single molecules using highly sensitive nanoelectronics is an exciting prospect in the field of sensors, particularly for neuro- and biosensor applications. "Use of noise signals to identify molecular activity ((interaction) or (active orbital)) is attractive for developing advanced sensing devices," explains corresponding author Megumi Akai-Kasaya. "We demonstrated that noise can be exploited to improve the signal detection ability of a device." The results of this successful demonstration will be published in the near future in a follow-up article. Signal detection sensitivity may be increased through controllable noise generation. These carbon nanotube-based devices illustrate that it is possible to detect single molecules through their unique noise signatures in the device current signals. Improved knowledge of the molecular-level origin of noise should lead to the development of electronics that use noise to improve their performance rather than degrade it.. Ref.A1321ELHLT-TAS5030-ATST 

Seoul Semiconductor has developed the industry’s smallest phase-cut DC LED driver series, with a power density 10X higher than conventional LED drivers. The NanoDriver Series is the world’s smallest miniature converter at just 13.5 mm wide, and is available in four versions rated for 16 W and 24 W output power for operating LED lighting with input power of 120 V/230 V (50 – 60 Hz). Manufactured with Seoul Semiconductor’s original Acrich technology, the NanoDriver Series features an IC directly attached to the substrate, dramatically reducing the size of the converter.(NanoDriver Series phase-cut LED drivers measure just 13.5 mm × 13.5 mm × 1.42 mm)In the future, Seoul Semiconductor will also launch the MicroDriver Series high performance drivers for LED lighting fixtures from 900 to 2400 lumens. The MicroDriver Series is designed with a miniature package that reduces the size of the converter by more than 10X to enable the integration of the control circuitry with the external driver, making it possible to mount more light sources on the board, reduce the size of the board. The NanoDriver Series requires few external components, and delivers 16 W/24 W of output power in a package just 13.5 mm × 13.5 mm × 1.42 mm. These drivers are ideal for downlight, flush mount, track and spotlight fixtures. Their small size enables ultra-thin and novel fixture designs in wall sconces, making conventional lamp replacement possible without the need for a large volume recess for the driver, or a reduction in the light output. The resulting decrease in the LED drivers’ physical size has significant business implications for the lighting industry, giving lighting designers the ability to shrink the size of light fixtures by as much as 20, which reduces shipping and storage costs. Because conventional LED drivers are both heavy and bulky, they are typically shipped via sea freight from manufacturers in Asia to European and North American fixture companies, with transit times up to six weeks. The NanoDriver Series are small and lightweight enough to make airfreight practical and economical, reducing transit time and making the overall supply chain more flexible and responsive. The NanoDriver Series is available in four models rated for output power of 16 W and 24 W, for LED assemblies operating at input voltages of 120 V/230 V (50 – 60 Hz). The drivers have typical efficiencies of 85 and power factor correction (PFC) of > 0.9, and are rated for inrush current of <30 mA, with an over-temperature protection feature that limits the LED current at temperatures above 160 °C. Operating temperature range is –40 °C to +70 °C (ambient) and –40 °C to +120 °C (at TC point). The drivers are UL recognized, provide flicker-free, low ripple current operation for phase-cut dimmers, and are compliant to California Title 24, enabling lighting designers to meet the most challenging design requirements, including low flicker, high power factor, Class B EMI and 2 kV surge. Ref.KY59-UR101

Researchers have proposed a design for the first DNA sequencer based on an electronic nanosensor that can detect tiny motions as small as a single atom. The proposed device—a type of capacitor, which stores electric charge—is a tiny ribbon of molybdenum disulfide suspended over a metal electrode and immersed in water. The ribbon is 15.5 nanometers (nm, billionths of a meter) long and 4.5 nm wide. Single-stranded DNA, containing a chain of bases (bits of genetic code), is threaded through a hole 2.5 nm wide in the thin ribbon. The ribbon flexes only when a DNA base pairs up with and then separates from a complementary base affixed to the hole. The membrane motion is detected as an electrical signal. As described in a new paper, the NIST team made numerical simulations and theoretical estimates to show the membrane would be 79 to 86 percent accurate in identifying DNA bases in a single measurement at speeds up to about 70 million bases per second. Integrated circuits would detect and measure electrical signals and identify bases. The results suggest such a device could be a fast, accurate and cost-effective DNA sequencer, according to the paper. Conventional sequencing, developed in the 1970s, involves separating, copying, labeling and reassembling pieces of DNA to read the genetic information. Newer methods include automated sequencing of many DNA fragments at once—still costly—and novel "nanopore sequencing" concepts. For example, the same NIST group recently demonstrated the idea of sequencing DNA by passing it through a graphene nanopore, and measuring how graphene's electronic properties respond to strain. The latest NIST proposal relies on a thin film of molybdenum disulfide—a stable, layered material that conducts electricity and is often used as a lubricant. Among other advantages, this material does not stick to DNA, which can be a problem with graphene. The NIST team suggests the method might even work without a nanopore—a simpler design—by passing DNA across the edge of the membrane. "This approach potentially solves the issue with DNA sticking to graphene if inserted improperly, because this approach does not use graphene, period," NIST theorist and lead author Alex Smolyanitsky said. "Another major difference is that instead of relying on the properties of graphene or any particular material used, we read motions electrically in an easier way by forming a capacitor. This makes any electrically conductive membrane suitable for the application." Nanomaterials expert Boris Yakobson of Rice University, a co-author on the paper, suggested the capacitor idea. Computational support was provided by the University of Groningen in the Netherlands. DNA has four bases. For the simulations, cytosine (C), which naturally pairs up with guanine (G), is attached to the inside of the pore. When a piece of DNA passes through the pore, any G in the strand temporarily attaches to the embedded C, pulling on the nanoribbon and signaling the electrode. The DNA sequence is determined by measuring how and when electrical blips vary over time. To detect all four bases, four nanoribbons, each with a different base attached to the pore, could be stacked vertically to create an integrated DNA sensor. The molybdenum disulfide ribbon is flexible enough to deform measurably in response to the forces required to break up a DNA pair, but rigid enough to have less ongoing, meaningless movement than graphene, potentially reducing unwanted noise in the sequencing signals. The deflection of the ribbon is exceedingly small, on the order of one angstrom, the size of a hydrogen atom. Its pulling force is on the order of 50 piconewtons, or trillionths of a newton, enough to break up the delicate chemical bonds between DNA bases. Researchers estimated how the device would perform in an integrated circuit and found the peak currents through the capacitor were measurable (50 to 70 picoamperes), even for the small nanoribbons studied. The current peaks are expected to be even larger in physical systems. The device size could be tweaked to make it even easier to measure sequencing signals. The NIST authors hope to build a physical version of the device in the future. For practical applications, the chip-sized DNA sequencing microfluidic technology might be combined with electronics into a single device small enough to be handheld. Reference: RFCS04021000BJTT1 RFCS04025000DBTT1 SC02201518    

New research, led by the University of Southampton, has demonstrated that a nanoscale device, called a memristor, could be the 'missing link' in the development of implants that use electrical signals from the brain to help treat medical conditions.Monitoring neuronal cell activity is fundamental to neuroscience and the development of neuroprosthetics – biomedically engineered devices that are driven by neural activity. However, a persistent problem is the device being able to process the neural data in real-time, which imposes restrictive requirements on bandwidth, energy and computation capacity.In a new study, published in Nature Communications, the researchers showed that memristors could provide real-time processing of neuronal signals (spiking events) leading to efficient data compression and the potential to develop more precise and affordable neuroprosthetics and bioelectronic medicines.Memristors are electrical components that limit or regulate the flow of electrical current in a circuit and can remember the amount of charge that was flowing through it and retain the data, even when the power is turned off.Lead author Isha Gupta, Postgraduate Research Student at the University of Southampton, said: "Our work can significantly contribute towards further enhancing the understanding of neuroscience, developing neuroprosthetics and bio-electronic medicines by building tools essential for interpreting the big data in a more effective way."The research team developed a nanoscale Memristive Integrating Sensor (MIS) into which they fed a series of voltage-time samples, which replicated neuronal electrical activity.Acting like synapses in the brain, the metal-oxide MIS was able to encode and compress (up to 200 times) neuronal spiking activity recorded by multi-electrode arrays. Besides addressing the bandwidth constraints, this approach was also very power efficient – the power needed per recording channel was up to 100 times less when compared to current best practice.Co-author Dr Themis Prodromakis at the University of Southampton said: "We are thrilled that we succeeded in demonstrating that these emerging nanoscale devices, despite being rather simple in architecture, possess ultra-rich dynamics that can be harnessed beyond the obvious memory applications to address the fundamental constraints in bandwidth and power that currently prohibit scaling neural interfaces beyond 1,000 recording channels."