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Friday, July 22, 2011

IPhone tracks blood glucose with a 'nano-tattoo'

Phone sensor: This modified iPhone case can be used to detect sodium levels via a nanosensor “tattoo.” Credit: Heather Clark and Matt Dubach

By Nick Flaherty

Researchers at Northeastern University in the US have developed a technique to track blood sugar via an iPhone, aiming at cyclists initially. 
The technique uses an injection of carefully chosen nanoparticles into the skin which fluoresce when exposed to a target molecule, such as sodium or glucose. An iPhone with a modified case that includes a fluorescent light and a sensor then tracks changes in the level of fluorescence, which indicates the amount of sodium or glucose present.
Heather Clark, a professor in the Department of Pharmaceutical Sciences at Northeastern University, presented this work at the BioMethods Boston conference at Harvard Medical School last week and reported in MIT's Technology Review.
The tattoos were originally designed as a way around the finger-prick bloodletting that is the standard technique for measuring glucose levels in those with diabetes. But Clark says they could be used to track many things besides glucose and sodium, offering a simpler, less painful, and more accurate way for many people to track many important biomarkers.
The tattoo developed by Clark's team contains 120nm-wide polymer nanodroplets of a fluorescent dye and a charge-neutralizing molecule.
The original reader was a large boxlike device but one of Clark's graduate students, Matt Dubach, improved upon that by making a modified iPhone case that allows any iPhone to read the tattoos.
Dubach and Clark hope to create an iPhone app that would easily measure and record sodium levels. 
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Tuesday, July 19, 2011

Soft memory for bioelectronic systems

By Nick Flaherty

Researchers from North Carolina State University have developed a memory device that is soft and functions well in wet environments, opening the door to a new generation of biocompatible electronic devices.
“We’ve created a memory device with the physical properties of Jell-O,” says Dr Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper describing the research.
Conventional electronics are typically made of rigid, brittle materials and don’t function well in a wet environment. “Our memory device is soft and pliable, and functions extremely well in wet environments – similar to the human brain,” Dickey says.
Prototypes of the device have not yet been optimized to hold significant amounts of memory, but work well in environments that would be hostile to traditional electronics. The devices are made using a liquid alloy of gallium and indium metals set into water-based gels, similar to gels used in biological research.
The device’s ability to function in wet environments, and the biocompatibility of the gels, mean that this technology holds promise for interfacing electronics with biological systems – such as cells, enzymes or tissue. “These properties may be used for biological sensors or for medical monitoring,” Dickey says.
The device functions much like so-called “memristors,” which are vaunted as a possible next-generation memory technology. The individual components of the “mushy” memory device have two states: one that conducts electricity and one that does not. These two states can be used to represent the 1s and 0s used in binary language. Most conventional electronics use electrons to create these 1s and 0s in computer chips. The mushy memory device uses charged molecules called ions to do the same thing.
In each of the memory device’s circuits, the metal alloy is the circuit’s electrode and sits on either side of a conductive piece of gel. When the alloy electrode is exposed to a positive charge it creates an oxidized skin that makes it resistive to electricity. We’ll call that the 0. When the electrode is exposed to a negative charge, the oxidized skin disappears, and it becomes conducive to electricity. We’ll call that the 1.
Normally, whenever a negative charge is applied to one side of the electrode, the positive charge would move to the other side and create another oxidized skin – meaning the electrode would always be resistive. To solve that problem, the researchers “doped” one side of the gel slab with a polymer that prevents the formation of a stable oxidized skin. That way one electrode is always conducive – giving the device the 1s and 0s it needs for electronic memory.
The paper, “Towards All-Soft Matter Circuits: Prototypes of Quasi-Liquid Devices with Memristor Characteristics,” was published online July 4 by Advanced Materials. The paper was co-authored by NC State Ph.D. students Hyung-Jun Koo and Ju-Hee So, and NC State INVISTA Professor of Chemical and Biomolecular Engineering Orlin Velev. The research was supported by the National Science Foundation and the U.S. Department of Energy.

Researchers make ferroelectric nanostructures directly on plastic

Researchers have developed a new way to fabricate nanometre-scale ferroelectric structures that could lead to a new generation of low cost energy harvesting devices and micromachined structures 
The key is that they have been able to build ferroelectric structures directly on flexible plastic substrates that would be unable to withstand the processing temperatures normally required to create such nanostructures.
The technique, which uses a heated atomic force microscope (AFM) tip to produce patterns, could facilitate high-density, low-cost production of complex ferroelectric structures for energy harvesting arrays, sensors and actuators.
Georgia Tech postdoctoral fellow Suenne Kim holds a sample of flexible polyimide substrate used in research on a new technique for producing ferroelectric nanostructures. Assistant professor Nazanin Bassiri-Gharb points...

"We can directly create piezoelectric materials of the shape we want, where we want them, on flexible substrates for use in energy harvesting and other applications," said Nazanin Bassiri-Gharb, co-author of the paper and an assistant professor in the School of Mechanical Engineering at the Georgia Institute of Technology. "This is the first time that structures like these have been directly grown with a CMOS-compatible process at such a small resolution. Not only have we been able to grow these ferroelectric structures at low substrate temperatures, but we have also been able to pattern them at very small scales."

This image shows the topography (by atomic force microscope) of a ferroelectric PTO line array crystallized on a 360-nanometer thick precursor film on polyimide.
The researchers have produced wires approximately 30 nanometers wide and spheres with diameters of approximately 10 nanometers using the patterning technique. Spheres with potential application as ferroelectric memory were fabricated at densities exceeding 200 gigabytes per square inch – currently the record for this perovskite-type ferroelectric material, said Suenne Kim, the paper's first author and a postdoctoral fellow in laboratory of Professor Elisa Riedo in Georgia Tech's School of Physics.
Ferroelectric materials are attractive because they exhibit charge-generating piezoelectric responses an order of magnitude larger than those of materials such as aluminum nitride or zinc oxide. The polarization of the materials can be easily and rapidly changed, giving them potential application as random access memory elements.
Until now, the challenges required that ferroelectric structures be grown on a single-crystal substrate compatible with high temperatures, then transferred to a flexible substrate for use in energy-harvesting.
The thermochemical nanolithography process, which was developed at Georgia Tech in 2007, addresses those challenges by using extremely localized heating to form structures only where the resistively-heated AFM tip contacts a precursor material. A computer controls the AFM writing, allowing the researchers to create patterns of crystallized material where desired. To create energy-harvesting structures, for example, lines corresponding to ferroelectric nanowires can be drawn along the direction in which strain would be applied.

Scanning electron microscope image shows a large PZT line array crystallized on a 240-nanometer thick precursor film on a platinized silicon wafer.

"The heat from the AFM tip crystallizes the amorphous precursor to make the structure," Bassiri-Gharb explained. "The patterns are formed only where the crystallization occurs."

To begin the fabrication, the sol-gel precursor material is first applied to a substrate with a standard spin-coating method, then briefly heated to approximately 250 degrees Celsius to drive off the organic solvents. The researchers have used polyimide, glass and silicon substrates, but in principle, any material able to withstand the 250-degree heating step could be used. Structures have been made from Pb(ZrTi)O3 – known as PZT, and PbTiO3 – known as PTO.

"We still heat the precursor at the temperatures required to crystallize the structure, but the heating is so localized that it does not affect the substrate," explained Riedo, a co-author of the paper and an associate professor in the Georgia Tech School of Physics.

The heated AFM tips were provided by William King, a professor in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign.

As a next step, the researchers plan to use arrays of AFM tips to produce larger patterned areas, and improve the heated AFM tips to operate for longer periods of time. The researchers also hope to understand the basic science behind ferroelectric materials, including properties at the nanoscale.

"We need to look at the growth thermodynamics of these ferroelectric materials," said Bassiri-Gharb. "We also need to see how the properties change when you move from the bulk to the micron scale and then to the nanometer scale. We need to understand what really happens to the extrinsic and intrinsic responses of the materials at these small scales."

Ultimately, arrays of AFM tips under computer control could produce complete devices, providing an alternative to current fabrication techniques.

"Thermochemical nanolithography is a very powerful nanofabrication technique that, through heating, is like a nanoscale pen that can create nanostructures useful in a variety of applications, including protein arrays, DNA arrays, and graphene-like nanowires," Riedo explained. "We are really addressing the problem caused by the existing limitations of photolithography at these size scales. We can envision creating a full device based on the same fabrication technique without the requirements of costly clean rooms and vacuum-based equipment. We are moving toward a process in which multiple steps are done using the same tool to pattern at the small scale."

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Using blood glucose to power implants

Electricity from Blood Sugar
By Nick Flaherty

Reseachers at the Department of Microsystems Engineering (IMTEK) of the University of Freiburg are developing biological fuel cells to provide power in the human body. 
Researchers have yet to find an optimal method for supplying implantable medical microsystems with electrical energy. The batteries of a pacemaker, for instance, need to be replaced after roughly eight years - meaning a strenuous and expensive surgical intervention for the patient, or rechargeable batteries that greatly reduce the patient’s quality of life. 
The idea behind Sven Kerzenmacher’s research is to use implantable glucose fuel cells based on noble metal catalysts like platinum. Such catalysts are particularly well suited for use in implant systems due to their long-term stability and the fact that they can be sterilized. In the future, systems equipped with these fuel cells could be supplied with power by way of a continuous electrochemical reaction between glucose and oxygen from the tissue fluid.
Kerzenmacher and his team aim to apply a thin coat of the fuel cells they have developed to the surface of the implant. The advantages of this technique over existing technologies stem from the fact that the fuel cells are only half as thick while delivering a 30 percent increase in performance. Moreover, platinum electrodes are not sensitive to unwanted chemical reactions like hydrolysis and oxidation. Kerzenmacher and his research group consisting of biologists, chemists, and engineers are currently developing new materials and techniques to improve the performance of the fuel cells.
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Tuesday, July 12, 2011

Leti Develops Ultra-Wideband Communications System for International Airports

By Nick Flaherty

French researchers at CEA-Leti have developed an ultra-wideband (UWB) radio chip and location software to help airport operators identify and control the continuous movements of ground crews and their vehicles.
The chip and software performance has been demonstrated at Portugal’s Faro Airport as part of the European Commission-funded LocON platform project to install new control-and-monitoring services for large airports. The platform, which integrates different wireless location systems and supports, gives ground-control managers a complete overview of the hive of activity on the tarmac and inside facilities, and allows communication with ground-control personnel.
Following activity on computer monitors, supervisors are better able to manage the often hectic, continuously changing situation on the tarmac, which increases operation efficiency – including the use of idle equipment – and allows them to alert personnel immediately of potential collisions or violations of safety and security rules.
The configurable and scalable system streamlines the integration of single-mode location systems such as WiFi-, UWB- and RFID-based systems with satellite navigation systems into a multi-modal hybrid system. The platform, based on IC tags on vehicles and worn by ground crews, reduces aircraft-loading times to the minimum, improves airplane turnaround time and increases airport throughput.
Working with its sister institute, CEA-List, Leti supplied an accurate and short-range indoor location system based on the UWB radio platform and the embedded low-level software. This system required the development not only of the complete middleware architecture, incorporating its control service, but also:
  • four UWB base stations organized in a network, allowing sub-meter location of mobile UWB elements
  • a gateway between the UWB network and the LocON middleware
  • software to secure the link between the gateway and the middleware, and
  • a location algorithm embedded in the mobile UWB elements, designed to operate with limited calculation resources
The system provides  a low-cost UWB location terminal with very low-power consumption (ASIC RF), incorporating a simple and efficient location algorithm. The challenge now is to develop a fully distributed system software based around this platform. “LocON demonstrates the value of Europe’s R&D partnerships in delivering solutions that solve everyday problems and improve quality of life for Europeans, and people all over the world,” said Laurent Malier at Leti CEO. “It also highlights Leti’s capabilities in UWB technology, which has many potential applications in both the public and private sectors.”

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Friday, July 08, 2011

Industry's First NVIDIA Fermi GPU OpenVPX Engine

480 cores on a board for military digital signal rpocessing

By Nick Flaherty

Marking a key move of massively parallel graphics technology from the PC desktop to the embedded world, Curtiss-Wright Controls Embedded Computing (CWCEC) has developed the industry's first openVPX board based on NVIDIA's Fermi graphics engine.
The VPX6-490 GPU Application Accelerator uses two NVIDIA GPUs based on the Fermi architecture, each with 240 CUDA cores. Integrated into a High Performance Embedded Computing (HPEC) subsystem, VPX6-490 functions as a co-processor attached to a host Intel-processor board and takes advantage of the new PCIe Expansion Plane definitions in the VITA 65 OpenVPX standard to provide off the shelf backplane support for high-speed interconnection between pairs of SBC/GPU
This combination is aimed at demanding military digital signal processing (DSP) applications such as C4ISR, EO/IR and SatCom.
"The VPX6-490 uniquely brings NVIDIA's new 240 core graphics processors to the rugged deployed environment, providing system integrators with the highest performance GPGPU embedded building blocks available," said Lynn Bamford, vice president and general manager of Curtiss-Wright Controls Embedded Computing. "Combined with our OpenVPX single board computers, FPGA engines and FMC I/O modules, we now offer the industry's most comprehensive and highest performance GPGPU solution for the most demanding HPEC applications."
"Rugged open-architecture processing modules, like Curtiss-Wright's VPX-490, will enable military system designers to leverage the massively parallel performance of our newest GPUs," said Taner Ozcelik, general manager, embedded and automotive business, NVIDIA.
The VPX6-490 takes full advantage of GPUs based on the NVIDIA Fermi architecture. Designed for high performance computing, the newest generation of NVIDIA processors feature larger internal shared memories, a completely new L2 cache, unified memory addressing and many other enhancements to improve CUDA-based applications performance and improve programmer productivity. The VPX6-490 supports its dual high performance GPU processors with a 2 Gbyte, 256-bit wide, 80 Gbyte/s GDDR5 memory subsystem designed to eliminate data bottlenecks and support large signal processing datasets into the onboard memory. Each GPU device supports a full 16-lane Gen2 PCIe interface to the backplane, supporting the maximum possible bandwidth between host and GPU. The VPX6-490 also supports 8-lane and 4-lane PCIe interfaces.

VPX6-490 Performance Features:
  • 6U OpenVPX GPGPU Application Accelerator
  • 80 Gbyte/s memory bandwidth
  • Enhanced GPGPU performance based on NVIDIA Fermi architecture:
  • 240 CUDA processor cores
  • 2 Gbytes GDDR5 memory
  • 256-bit memory interface
  • 16-lane Gen2 PCIe interface
  • Dual DVI graphics outputs
  • CUDA 4.0 library support
  • Rugged air-cooled and conduction-cooled variants
  • Temperature sensors
  • IPMI
  • 12V power

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Device captures ambient electromagnetic energy for power

Printed antennas and electronics capture energy to drive small electronic devices
By Nick Flaherty
Researchers in the US have developed a low cost way to capture and harness energy transmitted by such sources as radio and television transmitters, cell phone networks and satellite communications systems. By scavenging this ambient energy with ink-jet printed antenna, the technique could provide a new way to power networks of wireless sensors, microprocessors and communications chips.
"There is a large amount of electromagnetic energy all around us, but nobody has been able to tap into it," said Manos Tentzeris, a professor in the Georgia Tech School of Electrical and Computer Engineering who is leading the research. "We are using an ultra-wideband antenna that lets us exploit a variety of signals in different frequency ranges, giving us greatly increased power-gathering capability."
Tentzeris and his team are using inkjet printers to combine sensors, antennas and energy scavenging capabilities on paper or flexible polymers, including carbon nanotubes. The resulting self powered wireless sensors could be used for chemical, biological, heat and stress sensing for defence and industry; radio frequency identification (RFID) tagging for manufacturing and shipping, and monitoring tasks in many fields including communications and power usage.

Georgia Tech graduate student Rushi Vyas (front) holds a prototype energy-scavenging device, while School of Electrical and Computer Engineering professor Manos Tentzeris displays a miniaturized flexible antenna that was inkjet-printed.

Prof Manos Tentzeris displays an inkjet-printed rectifying antenna, or rectenna, used to convert microwave energy to DC power. 

The team's scavenging devices can capture this energy, convert it from AC to DC, and then store it in capacitors and batteries. The scavenging technology can take advantage presently of frequencies from FM radio to radar, a range spanning 100MHz to 15GHz. Scavenging experiments using TV bands have already yielded power amounting to hundreds of microwatts, and multi-band systems are expected to generate one milliwatt or more. That amount of power is enough to operate many small electronic devices, including a variety of sensors and microprocessors.
By combining energy scavenging technology with supercapacitors and cycled operation, the Georgia Tech team expects to power devices requiring above 50 milliwatts. In this approach, energy builds up in a battery-like supercapacitor and is utilized when the required power level is reached.
The researchers have already successfully operated a temperature sensor using electromagnetic energy captured from a television station that was half a kilometer distant. They are preparing another demonstration in which a microprocessor-based microcontroller would be activated simply by holding it in the air.
Exploiting a range of electromagnetic bands increases the dependability of energy scavenging devices, explained Tentzeris, who is also a faculty researcher in the Georgia Electronic Design Center at Georgia Tech. If one frequency range fades temporarily due to usage variations, the system can still exploit other frequencies.
The scavenging device could be used by itself or in tandem with other generating technologies. For example, scavenged energy could assist a solar element to charge a battery during the day. At night, when solar cells don't provide power, scavenged energy would continue to increase the battery charge or would prevent discharging.
Using ambient electromagnetic energy could also provide a form of system backup for embedded systems. If a battery or a solar-collector/battery package failed completely, scavenged energy could allow the system to transmit a wireless distress signal while also potentially maintaining critical functionalities.

The researchers are using inkjet technology to print these energy scavenging devices on paper or flexible paper-like polymers – a technique they already using to produce sensors and antennas. The result would be paper-based wireless sensors that are self powered, low cost and able to function independently almost anywhere.
To print electrical components and circuits, the Georgia Tech researchers use a standard materials inkjet printer. However, they add what Tentzeris calls "a unique in house recipe" containing silver nanoparticles and/or other nanoparticles in an emulsion. This approach enables the team to print not only RF components and circuits, but also novel sensing devices based on such nanomaterials as carbon nanotubes.
When Tentzeris and his research group began inkjet printing of antennas in 2006, the paper-based circuits only functioned at frequencies of 100 or 200MHz, recalled Rushi Vyas, a graduate student who is working with Tentzeris and graduate student Vasileios Lakafosis on several projects.
"We can now print circuits that are capable of functioning at up to 15 GHz -- 60 GHz if we print on a polymer," Vyas said. "So we have seen a frequency operation improvement of two orders of magnitude."
The researchers believe that self-powered, wireless paper-based sensors will soon be widely available at very low cost. The resulting proliferation of autonomous, inexpensive sensors could be used for applications that include:
  • Airport security: Airports have both multiple security concerns and vast amounts of available ambient energy from radar and communications sources. These dual factors make them a natural environment for large numbers of wireless sensors capable of detecting potential threats such as explosives or smuggled nuclear material.
  • Energy savings: Self-powered wireless sensing devices placed throughout a home could provide continuous monitoring of temperature and humidity conditions, leading to highly significant savings on heating and air conditioning costs. And unlike many of today's sensing devices, environmentally friendly paper-based sensors would degrade quickly in landfills.
  • Structural integrity: Paper or polymer-based sensors could be placed throughout various types of structures to monitor stress. Self powered sensors on buildings, bridges or aircraft could quietly watch for problems, perhaps for many years, and then transmit a signal when they detected an unusual condition.
  • Food and perishable material storage and quality monitoring: Inexpensive sensors on foods could scan for chemicals that indicate spoilage and send out an early warning if they encountered problems.
  • Wearable bio-monitoring devices: This emerging wireless technology could become widely used for autonomous observation of patient medical issues.
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