'Breathalyzers' May Be Useful for Medical Diagnostics

The researchers demonstrated their approach is capable of rapidly detecting biomarkers in the parts per billion to parts per million range, at least 100 times better than previous breath-analysis technologies, said Carlos Martinez, an assistant professor of materials engineering at Purdue who is working with researchers at the National Institute of Standards and Technology.

"People have been working in this area for about 30 years but have not been able to detect low enough concentrations in real time," he said."We solved that problem with the materials we developed, and we are now focusing on how to be very specific, how to distinguish particular biomarkers."

The technology works by detecting changes in electrical resistance or conductance as gases pass over sensors built on top of"microhotplates," tiny heating devices on electronic chips. Detecting biomarkers provides a record of a patient's health profile, indicating the possible presence of cancer and other diseases.

"We are talking about creating an inexpensive, rapid way of collecting diagnostic information about a patient," Martinez said."It might say, 'there is a certain percentage that you are metabolizing a specific compound indicative of this type of cancer,' and then additional, more complex tests could be conducted to confirm the diagnosis."

The researchers used the technology to detect acetone, a biomarker for diabetes, with a sensitivity in the parts per billion range in a gas mimicking a person's breath.

Findings were detailed in a research paper that appeared earlier this year in the IEEE Sensors Journal, published by the Institute of Electrical and Electronics Engineers' IEEE Sensors Council. The paper was co-authored by Martinez and NIST researchers Steve Semancik, lead author Kurt D. Benkstein, Baranidharan Raman and Christopher B. Montgomery.

The researchers used a template made of micron-size polymer particles and coated them with far smaller metal oxide nanoparticles. Using nanoparticle-coated microparticles instead of a flat surface allows researchers to increase the porosity of the sensor films, increasing the"active sensing surface area" to improve sensitivity.

A droplet of the nanoparticle-coated polymer microparticles was deposited on each microhotplate, which are about 100 microns square and contain electrodes shaped like meshing fingers. The droplet dries and then the electrodes are heated up, burning off the polymer and leaving a porous metal-oxide film, creating a sensor.

"It's very porous and very sensitive," Martinez said."We showed that this can work in real time, using a simulated breath into the device."

Gases passing over the device permeate the film and change its electrical properties depending on the particular biomarkers contained in the gas.

Such breathalyzers are likely a decade or longer away from being realized, in part because precise standards have not yet been developed to manufacture devices based on the approach, Martinez said.

"However, the fact that we were able to do this in real time is a big step in the right direction," he said.

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Lower Power Consumption for Electronics: Thin Film Packaged MEMS Resonator With Industry Record Q Factor and Low Bias Voltage

This groundbreaking resonator paves the way towards miniaturization and low power consumption of timing devices used in a variety of applications such as consumer electronics and automotive electronics.

MEMS resonators offer enhanced miniaturization over conventional resonators such as quartz crystals and piezoelectric ceramics. However, state-of-the art MEMS resonators suffer from a low Q factor and a high bias voltage. Panasonic and imec developed a novel packaged MEMS resonator achieving the highest Q factor reported in the industry until now (220,000 at a resonant frequency f=20MHz (f•Q product of 4.3X10¹²Hz)) and low bias voltage by combining different advanced MEMS technologies.

The application of a torsional vibration mode enables low anchor losses and lower squeeze film damping compared to flexural mode resonators, resulting in a higher Q factor. Since the Q factor also depends on the ambient pressure and starts to decrease above a critical pressure due to viscous and squeeze film damping, imec and Panasonic vacuum encapsulated the resonator in a hermetically sealed environment. This thin-film encapsulation of the MEMS with a 4µm thick SiGe film is realized with a monolithic fabrication process with the MEMS.

The narrow 130nm gap between the beam and drive and sense electrodes enables a low bias voltage (1.8Vdc) and thus eliminates a charge pump in the oscillator circuit. Moreover, using sacrificial layer etching through a microcrystalline silicon germanium layer minimizes the chances of deposition of the sealing material inside the cavity and thus enables to position the etching holes right above the beam surface, leading to a smaller chip size.

The packaged MEMS resonator was realized as part of imec's CMORE service which offers heterogeneous integration services to the industry. Imec builds on its expertise in many research areas to tune and extend CMOS processes with new processing steps to make novel CMOS micro- and nanodevices, adding functions other than logic and memory to the chips. Possible applications of such MEMS devices are smart sensors, actuators, power scavengers, resonators, biochips, micro-implantable appliances, or solar cells. Imec's CMORE services range from development-on-demand, over prototyping, to low-volume production.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Intelligent Detector Provides Real-Time Information on Available Parking Spaces

Testing of the new technology is currently underway at the Universitat Politècnica de Catalunya's North Campus, and a patent is being sought. The system can be used to provide users with information via mobile devices such as phones, laptop computers, and iPads, or using luminous panels in public thoroughfares. In the coming months it will be installed in the 22@Barcelona innovation district and in downtown Figueres.

A team at the Department of Electronic Engineering of the Castelldefels School of Telecommunications and Aerospace Engineering (EETAC), part of the Universitat Politècnica de Catalunya (UPC), has designed a new method for continuously detecting the presence of vehicles using both an optical and a magnetic sensor. The detector incorporates the two sensors in a 4 by 13 cm casing that is set into the pavement of each parking space. Urbiòtica, a company set up by UPC professors and their industrial partners, is testing the system at the UPC's North Campus prior to placing it on the market.

The device works by first detecting the sudden change in the amount of light reaching the pavement that occurs when a vehicle passes over it. The optical sensor then activates the magnetic sensor to verify that the shadow is being produced by a vehicle. This is done by detecting the slight disturbance in Earth's magnetic field that occurs when a car passes over or stops above the device. The two sensors are connected to a microcontroller that executes an algorithm to determine whether or not a vehicle is present. The system's optical sensor is always active but consumes an insignificant amount of power.

When a vehicle is detected, the microcontroller sends a radio-frequency signal, which conveys this information to an antenna connected to a transceiver. This way of transmitting signals is much more economical than using wiring. The transceiver, designed for installation on street lights, receives the information and transmits it to the database or control center within seconds (using technologies such as Wi-Fi or GPRS). Potential clients for the system include municipal services and parking lot operators.

According to Ramon Pallàs, head of the UPC team that developed the technology (for which a patent is being sought), the plan is to make the information available on luminous panels on public thoroughfares. Users will also be able to receive parking information on mobile devices such as phones, laptop computers, and iPads.

The innovative features of the product (which the UPC's AntenaLAB group also worked on) relate to the field of sensors, the circuits connecting the sensors to the microcontroller, the method for supplying power to the sensors, and management of the power supply for the system as a whole.

Continuous operation with low power consumption

The invention overcomes the shortcomings of the best existing systems for detecting stationary vehicles. There currently exist devices that emit a signal when a car passes over a sensor, but they do not detect whether the vehicle stops. In an enclosed facility these systems can be used to count vehicles entering and leaving and thus determine the number of parking spaces available, but they do not indicate where the free spaces are. Also, the magnetic sensors now in use consume too much energy to be kept running all the time.

In contrast, the system developed by the UPC group and marketed by Urbiòtica operates continuously and uses very little power because the optical sensor is the only component that is always active and the magnetic sensor is activated less frequently than in other similar systems. The fact that the sensors are connected directly to the microcontroller, without any intermediate electronic circuit, also reduces power consumption.

Practical applications

The new system can be used to manage and monitor vehicles on public and private thoroughfares, particularly in urban areas. This makes it possible to monitor points of access to centers of population, restricted zones, security zones, and grade crossings, and to manage parking on streets, at airports, and in commercial and underground parking areas. These applications can reduce the time drivers spend looking for a parking spot, resulting in lower fuel consumption and less pollution.

The characteristics of the system also facilitate other applications, such as the reservation of parking spaces for disabled drivers and payment based on the real time that a parking space is used. The system could also be used to detect areas where lighting is absent or insufficient.

Once pilot testing has been successfully completed, the system will be installed in the 22@Barcelona innovation district (from December on) as part of a Barcelona City Council project to deploy sensor systems, and in the town of Figueres (early in 2011), where it will be used to monitor traffic entering and leaving the city center.

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Project Pioneers Use of Silicon-Germanium for Space Electronics Applications

Titled"SiGe Integrated Electronics for Extreme Environments," the$12 million, 63-month project was funded by the National Aeronautics and Space Administration (NASA). In addition to Georgia Tech, the 11-member team included academic researchers from the University of Arkansas, Auburn University, University of Maryland, University of Tennessee and Vanderbilt University. Also involved in the project were BAE Systems, Boeing Co., IBM Corp., Lynguent Inc. and NASA's Jet Propulsion Laboratory.

"The team's overall task was to develop an end-to-end solution for NASA -- a tested infrastructure that includes everything needed to design and build extreme-environment electronics for space missions," said John Cressler, who is a Ken Byers Professor in Georgia Tech's School of Electrical and Computer Engineering. Cressler served as principal investigator and overall team leader for the project.

A paper on the project findings will appear in December inIEEE Transactions on Device and Materials Reliability,2010. During the past five years, work done under the project has resulted in some 125 peer-reviewed publications.

Unique Capabilities

SiGe alloys combine silicon, the most common microchip material, with germanium at nanoscale dimensions. The result is a robust material that offers important gains in toughness, speed and flexibility.

That robustness is crucial to silicon-germanium's ability to function in space without bulky radiation shields or large, power-hungry temperature control devices. Compared to conventional approaches, SiGe electronics can provide major reductions in weight, size, complexity, power and cost, as well as increased reliability and adaptability.

"Our team used a mature silicon-germanium technology -- IBM's 0.5 micron SiGe technology -- that was not intended to withstand deep-space conditions," Cressler said."Without changing the composition of the underlying silicon-germanium transistors, we leveraged SiGe's natural merits to develop new circuit designs -- as well as new approaches to packaging the final circuits -- to produce an electronic system that could reliably withstand the extreme conditions of space."

At the end of the project, the researchers supplied NASA with a suite of modeling tools, circuit designs, packaging technologies and system/subsystem designs, along with guidelines for qualifying those parts for use in space. In addition, the team furnished NASA with a functional prototype -- called a silicon-germanium remote electronics unit (REU) 16-channel general purpose sensor interface. The device was fabricated using silicon-germanium microchips and has been tested successfully in simulated space environments.

A New Paradigm

Andrew S. Keys, center chief technologist at the Marshall Space Flight Center and NASA program manager, said the now-completed project has moved the task of understanding and modeling silicon-germanium technology to a point where NASA engineers can start using it on actual vehicle designs.

"The silicon-germanium extreme environments team was very successful in doing what it set out to do," Keys said."They advanced the state-of-the-art in analog silicon-germanium technology for space use -- a crucial step in developing a new paradigm leading to lighter weight and more capable space vehicle designs."

Keys explained that, at best, most electronics conform to military specifications, meaning they function across a temperature range of minus- 55 degrees Celsius to plus-125 degrees Celsius. But electronics in deep space are typically exposed to far greater temperature ranges, as well as to damaging radiation. The Moon's surface cycles between plus-120 Celsius during the lunar day to minus-180 Celsius at night.

The silicon-germanium electronics developed by the extreme environments team has been shown to function reliably throughout that entire plus-120 to minus-180 Celsius range. It is also highly resistant or immune to various types of radiation.

The conventional approach to protecting space electronics, developed in the 1960s, involves bulky metal boxes that shield devices from radiation and temperature extremes, Keys explained. Designers must place most electronics in a protected, temperature controlled central location and then connect them via long and heavy cables to sensors or other external devices.

By eliminating the need for most shielding and special cables, silicon-germanium technology helps reduce the single biggest problem in space launches -- weight. Moreover, robust SiGe circuits can be placed wherever designers want, which helps eliminate data errors caused by impedance variations in lengthy wiring schemes.

"For instance, the Mars Exploration Rovers, which are no bigger than a golf cart, use several kilometers of cable that lead into a warm box," Keys said."If we can move most of those electronics out to where the sensors are on the robot's extremities, that will reduce cabling, weight, complexity and energy use significantly."

A Collaborative Effort

NASA currently rates the new SiGe electronics at a technology readiness level of six, which means the circuits have been integrated into a subsystem and tested in a relevant environment. The next step, level seven, involves integrating the SiGe circuits into a vehicle for space flight testing. At level eight, a new technology is mature enough to be integrated into a full mission vehicle, and at level nine the technology is used by missions on a regular basis.

Successful collaboration was an important part of the silicon-germanium team's effectiveness, Keys said. He remarked that he had"never seen such a diverse team work together so well."

Professor Alan Mantooth, who led a large University of Arkansas contingent involved in modeling and circuit-design tasks, agreed. He called the project"the most successful collaboration that I've been a part of."

Mantooth termed the extreme-electronics project highly useful in the education mission of the participating universities. He noted that a total of 82 students from six universities worked on the project over five years.

Richard W. Berger, a BAE Systems senior systems architect who collaborated on the project, also praised the student contributions.

"To be working both in analog and digital, miniaturizing, and developing extreme-temperature and radiation tolerance all at the same time -- that's not what you'd call the average student design project," Berger said.

Miniaturizing an Architecture

BAE Systems' contribution to the project included providing the basic architecture for the remote electronics unit (REU) sensor interface prototype developed by the team. That architecture came from a previous electronics generation: the now cancelled Lockheed Martin X-33 Spaceplane initially designed in the 1990s.

In the original X-33 design, Berger explained, each sensor interface used an assortment of sizeable analog parts for the front end signal receiving section. That section was supported by a digital microprocessor, memory chips and an optical bus interface -- all housed in a protective five-pound box.

The extreme environments team transformed the bulky X-33 design into a miniaturized sensor interface, utilizing silicon germanium. The resulting SiGe device weighs about 200 grams and requires no temperature or radiation shielding. Large numbers of these robust, lightweight REU units could be mounted on spacecraft or data-gathering devices close to sensors, reducing size, weight, power and reliability issues.

Berger said that BAE Systems is interested in manufacturing a sensor interface device based on the extreme environment team's discoveries.

Other space-oriented companies are also pursuing the new silicon-germanium technology, Cressler said. NASA, he explained, wants the intellectual-property barriers to the technology to be low so that it can be used widely.

"The idea is to make this infrastructure available to all interested parties," he said."That way it could be used for any electronics assembly -- an instrument, a spacecraft, an orbital platform, lunar-surface applications, Titan missions -- wherever it can be helpful. In fact, the process of defining such an NASA mission-insertion road map is currently in progress."

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