eReport

June 2008

BI Technologies Expands Molded Inductor Family with Miniature and Custom Devices

For design engineers who require a magnetic solution beyond the standard inductor offering, TT electronics BI Technologies has expanded its molded inductor product line to include a miniature device and custom capabilities. The latest addition to the HM72A series is a molded inductor 1.6 mm thick in a package measuring 6 mm by 6 mm.

"In addition to developing a miniature inductor for space constrained applications, we are now maximizing our specialty tooling expertise and offering custom inductor solutions," said David Smolik, director of product development for TT electronics' BI Technologies.  "Expanding our molded inductor product line and offering custom capabilities allow us to better serve our customers specific needs."

Typical applications for the HM72A low profile molded inductor include servers, notebooks, work stations, DC/DC converters, point-of-load modules, telecommunications, datacom, industrial equipment and automotive designs.

The HM72A surface mount inductor features a pressed powdered iron alloy core construction. The inductor is capable of controlling power losses in switching frequencies ranging from 300 kHz to 1 MHz. Inductance values range from 100 nH to 33 mH, with saturation levels to 80 A.  Operating temperature ranges from -40°C to 155°C, with a maximum temperature rise rating of 50°C. Custom devices are also available.

Typical pricing for the HM72A series low profile molded inductor is approximately $0.55 to 0.85 each, depending on quantity.  Lead time is from stock to 10 weeks.

New General-Purpose Latches for Non-Automotive Applications

Allegro MicroSystems, Inc. has released two temperature-stable and stress-resistant Hall-effect latches, especially suited for operation in consumer and industrial products. Superior high-temperature performance is made possible through Dynamic Offset Cancellation, which reduces the residual offset voltage normally caused by device package overmolding, temperature dependencies and thermal stress. The two devices are targeted at non-automotive applications and are identical except for their magnetic switchpoints.

Both devices include, on a single silicon chip, a voltage regulator, a Hall-voltage transducer, a small-signal amplifier, chopper stabilization, a Schmitt trigger and a short-circuit protected open-collector output to sink up to 25 mA. A south polarity magnetic field of sufficient strength is required to turn the output on. A north polarity field of sufficient strength is necessary to turn the output off. An onboard regulator permits operation with supply voltages in the range of 4.2 to 24 volts with an operating temperature range of -40°C to 125°C.

Allegro’s A3290 and A3291 devices are available in a three-lead single in-line package (UA) and a SOT-23W surface mount package (LH). The A329xKLHLT-T is priced at $0.44 and the A329xKUA-T is priced at $0.46 both in quantities of 1,000. They both have a 12 to 14 week typical lead-time to market.

RLS Magnetic Rotary Encoders Certified by FIA for Motorsports Racing

RM22 magnetic actuator mounts directly on the end of the shaft, while the encoder body is located in the clutch housing of Salakazi drag motorcycle.  Rugged encoder stands up to extreme acceleration and heat as the 1500 hp cycle races beyond 300 km/h in under 7 seconds.

Engineered for extreme service conditions, RLS magnetic rotary encoders from Renishaw have been certified by FIA (Federation Internationale de  L'Automobile) for motorsports, including Formula 1 racing.  Special, custom-engineered high-temperature versions of the RM22 magnetic encoder have been homologated for speed and position control.  The encoders provide by-wire feedback for wheel speed, steering and gear-box applications.  Engineered by RLS for racing demands, the custom RM22 encoders provide ±0.5° accuracy at speeds to 60,000 rpm and temperatures up to 170°C for extended periods.  An earlier custom version of the RM22 was run by an F1 team in 2007.

Beside Formula 1 racing, Europe's fastest drag racing motorcycle team, Salakazi Racing of Finland, uses special RM22 encoders to monitor crankshaft position and clutch speed to minimize wheel spin in accelerating to speeds in excess of 300 km/h.  "I honestly think that only a space rocket would be a tougher environment for the encoder," says Peti Makinen, Salakazi's technical chief.

Standard RLS magnetic encoders have been selected for by-wire systems in automobiles, off-road vehicles, lift equipment, defense applications and marine vessels.  The non-contact, solid-state encoders are available in 7-bit to 13-bit models and industry-standard absolute, incremental or linear output formats.  The magnetic encoders deliver high-resolution positioning (up to 8,192 count per revolution).  Standard models are rated for speeds to 30,000 rpm and temperatures from -40°C to 125°C.  The rugged encoders work in tough conditions — shock, vibration, pressures, temperature extremes, high speeds, high acc/dec, even immersion — while delivering high performance at low cost.

Non-contact, two-part design provides frictionless, wear-free, low-inertia operation and removes the need for seals or bearings, simplifying installation and ensuring long-term reliability.  The compact encoder body is 22 mm in diameter and provides dirt immunity to IP68.  The encoder comprises a magnetic actuator mounted on a shaft and separate metal-shell encoder body.  Rotation of the magnet is sensed by a custom chip inside the encoder body and is processed to give the required output format.

The magnetic encoder range is designed and manufactured in Slovenia by RLS d.o.o, Renishaw’s partner in encoder technology.  The miniature magnetic encoders come in packaged, component and modular models.  Exceptional design flexibility and custom engineering enable RLS to provide cost-effective, fit-and-forget positioning solutions to a wide range of industries and applications.  The web site provides a custom design form for listing application requirements that fall outside the specifications for standard models. 

Danaher Motion Introduces New Dover Non-Contact MAB-100 Linear Motor Stage

Danaher Motion has introduced the Dover MAB-100 Linear Motor Stage. The compact (63.5 mm tall by 88.9 mm wide by 266.7 mm long; 2.5 inches by 3.5 inches by 10.5 inches) MAB-100 utilizes a unique air bearing guideway to deliver precise, 100 percent friction-free straight-line motion up to 100 mm in length.  Its non-contact design delivers improved performance as well as reduced overall cost of ownership, maintenance requirements and machine down time when compared with linear motor stages with contact components.

“The MAB-100 is specifically engineered to help OEMs build a better machine, faster, by delivering precise, repeatable and reliable performance within a small footprint.  As a result, this small stage is ideally suited for demanding applications in the Life Sciences,  Data Storage, Semiconductor, and Factory Automation markets.  And with a completely non-contact complement of components, this linear stage will not generate any particles, allowing it to meet Class 1 cleanroom standards when used with appropriate input air filtration,” says Lou Elias, Small Stages Segment Manager, Danaher Motion - Dover.

The MAB-100 has no recirculating bearings or anti-creep mechanisms.  As a result, motion artifacts such as friction, heat and debris that can negatively impact linear motor stage and overall machine performance are completely eliminated.  Additionally, the MAB-100 is driven by a non-contact, brushless servo motor with a unique moving magnet design.  This eliminates moving motor cables, enabling better packaging and improved cable service reliability.  Overall benefits include reduced parts counts, less weight, a small footprint and ease of integration into machine builder and end user equipment.

Position feedback is provided by a linear optical encoder with a resolution of up to 5 nanometers.  The encoder features an index signal that enables precise position registration upon power-up.  The read head is mounted on a stationary base, eliminating the need for moving cables that can require regular maintenance resulting in increased machine downtime.  A pair of built-in, adjustable limit switches provide end of travel sensing, while rubber stops provide an additional layer of protection. 

The MAB-100 is also available with an embedded, high performance drive and control, which adds just 58mm to the overall length of the stage.  This “Smart Stage” model (MAB-100/HRC) requires only an external 24 VDC power supply and an RS-232 serial link for communication.  It can then function as an intelligent slave to a host computer over the serial interface, or it can be pre-programmed to auto-run sophisticated motion sequences as a stand-alone device.  This model features 4096X encoder interpolation resulting in a resolution of 5 nanometers.

MAB-100 linear motor stages have a load capacity of 2.5 kg and deliver 11 micron accuracy, with bi-directional repeatability of <0.032 microns.  They keep pitch and yaw to less than ± 7 uradians (± 1.5 arc-sec), with flatness and straightness kept under ± 200 nanometers.  Resolution options from 5 microns to 5 mm are available.

New Series of Inductive Components Enhance Industry-Leading Magnetic Product Range

Murata Power Solutions has added 10 new families of inductive components to its existing portfolio. The new introductions amount to well over 100 new part numbers and enable Murata Power Solutions to further enhance their comprehensive offering of wound ferrite magnetics for use in a wide range of power and EMC filtering applications.

The families comprise bobbin wound surface mount inductors, vertical mount leaded torroid inductors, low-profile shielded and unshielded surface mount inductors, flat coil surface mount power inductors and leaded common mode chokes.

All of the parts are fully RoHS compliant and are manufactured using UL 94V-0 approved materials. The new inductors have an operating temperature range of -40ºC to 125ºC making them well suited for applications requiring dependable, high temperature performance. The new range of common mode chokes meanwhile is suitable for use between -40ºC and 85ºC.

 “By adding a large and varied selection of new parts we are now able to offer a truly complete range of leading technology inductive components that address a huge range of applications across many industry sectors,” said Andrea Polti, global magnetics product manager, Murata Power Solutions. “Adding to our inductive product range further enhances Murata Power Solutions’ reputation as a frontrunner in the power electronics market.”

AS5243 - a System-On-Chip Combines Integrated Hall Elements, Analog Front End and Digital Signal Processing in a Single Device

austriamicrosystems  has supplied the AS5243, a redundant 10-bit magnetic rotary encoder IC, to Mega -Line Racing Electronic GmbH, a specialist in development of high performance automotive racing applications. The AS5243 is used to measure the absolute position of the barrel shaft in the gearbox to ensure an optimized gear change. AS5243 has been successfully tested in the Audi R10, which is the first diesel powered car winning the Le Mans 24 hours, one of the most ambitious races in the world.

The absolute magnetic shaft encoder developed by Mega-Line Racing Electronic is based on austriamicrosystems’ AS5243 redundant magnetic angular position sensor device which, due to its contactless measurement method, makes the system highly reliable and resistant to adverse environmental conditions such as dust, moisture, vibration or extended temperature conditions. With this sensor the abrasion over the economic life-time of the gearbox can be monitored. The high performance 10 bit resolution analog output and the extended temperature range up to 150°C (ambient) ideally meets the demands of many safety critical automotive, industrial and robotics applications.

"Our close collaboration with Mega-Line Racing Electronic helps us to be successful with innovative solutions on the market," said Bernhard Czar, Director Marketing Automotive at austriamicrosystems. "austriamicrosystems’ wide portfolio of magnetic angular position sensors meet a broad range of customer demands. We look forward to seeing further creative products emerging out of our partnership with MEGA-Line Racing Electronic.”

“We are excited to be working with austriamicrosystems and their new AS5243 absolute angular position sensor technology,” said Erwin Gassner, CEO of Mega-Line Racing Electronic. “This magnetic encoder technology enables us to get an absolute feedback about the most important gearbox parameter. The barrel position is used to optimize the whole gear change sequence. This sensor has to be absolutely reliable and using the freely programmable AS5243 we do not even need any calibration procedure in the car.”

The AS5243 is a contactless magnetic angle position sensor for accurate measurement up to 360° and includes two AS5143 devices in a punched stacked lead frame. It is a system-on-chip combining integrated Hall elements, analog front end and digital signal processing in a single device. The AS5243 provides two separated programmable analog outputs which can be configured in many ways, including user programmable angular range, adjustable output voltage range, voltage or current output, etc.
An internal voltage regulator allows operation of the AS5243 from 3.3V or 5.0V supplies. The AS5243 can detect 1,024 absolute positions over a full turn, 180 and 90 degrees which correspond to a resolution of minimum 0.087 degrees. Additional features include a user programmable zero position and a safety feature that constantly monitors the presence of the magnet. The AS5243 is available in a 7 by 7 mm QFN32 package.

Toroidal High-Temperature Inductor Offers Low Inductance Down to 0.39μH and Lowest DCR
with Vertical- and Horizontal-Mount Options

Vishay Intertechnology, Inc. has released a new toroidal, high-current, high-temperature inductor that offers the industry's highest rated and saturation current and the industrys lowest inductance and DCR.
With a high operating temperature rating to 200°C and a toroidal design to reduce EMI, the TJ3-HT inductor is optimized for switching power supplies, EMI/RFI filtering, and output chokes in automotive, and deep well drilling products.
The low-cost device offers designers horizontal and vertical mount options to optimize the PCB layout. With 10 standard inductance values to choose from, the inductor features a maximum DCR range from 0.108Ω down to 0.0016Ω when vertically mounted and 0.118Ω to 0.002Ω when horizontally mounted.

The TJ3-HT offers a wide inductance range from 100 μH down to 0.39 μH, with a high rated current from 2.25 A up to 32 A, and saturation current from 1.15 A up to 23 A. The inductor provides low magnetic radiation and is RoHS compliant. Custom values and current ratings are available upon request.

Samples and production quantities of the new TJ3-HT inductor are available now. Lead time for production quantities is 10 weeks. Pricing for US delivery only in 5,000-piece quantities is $0.60.

Nominate Your Company for the 2008 Magnetics Innova Awards

The Innova Awards are announced annually by Magnetics Business & Technology magazine and feature leading companies within the magnetics market who have shown through their products and services, the most innovative and advanced technology breakthroughs. These awards are designed to recognize companies that are striving for excellence in industry leadership, product development excellence, best technology and outstanding magnetics applications.

Nominations will be accepted only electronically by email. Send your nomination in the body of your email letter and include supporting material as attachments. Submit to Heather Krier at heatherk@infowebcom.com.

All nominations must be received by August 1, 2008. Winners will be featured in the Dec 08/Jan 09 issue of Magnetics Business & Technology magazine.

For more information visit www.magneticsmagazine.com/innova.htm.

Did you miss the 2008 Magnetics Conference?

The conference proceedings from the 2008 Magnetics Conference held in Denver, Colo. on May 15-16, are available on CD-ROM and include audio and video of select presentations.

Click Here to Order!

Magnetics Business & Technology Magazine Now Available Online Visit www.MagneticsMagazine.com to download the latest issue.

Researchers working at the National Institute of Standards and Technology (NIST) have discovered that a new class of iron-based superconductors discovered earlier this year shares similar unusual magnetic properties with previously known high-temperature superconductors based on copper-oxide materials. The work* emphasizes a critical but as yet unexplained link between magnetism and high-temperature superconductors.

The importance of magnetism to high-temperature (HTc) superconductors is remarkable because magnetism strongly interferes with conventional, low-temperature superconductors, but now may prove to be an integral element of HTc materials. These superconductors may one-day enable energy and environmental gains by significantly improving the efficiency of electricity storage and transmission over long distances.

The team working at NIST, which included researchers from the University of Tennessee at Knoxville, Oak Ridge National Laboratory, the University of Maryland, Ames Laboratory, Iowa State University and the Beijing National Laboratory for Condensed Matter Physics, used neutron beams to demonstrate that, like copper-oxide superconductors, the new iron-based HTc materials discovered earlier this year by Japanese researchers share an unusual magnetic structure with magnetically active layers interspersed with layers of nonmagnetic material.

* C. de la Cruz, Q. Huang, J.W. Lynn, J. Li, W. Ratcliff II, J.L. Zarestky, H.A. Mook, G.F. Chen, J.L. Luo, N.L. Wang and P. Dai. Magnetic order close to superconductivity in the iron-based layered La(O1-xFx)FeAs systems. Nature Advanced Online Publication, May 28, 2008.

New MRI System Under Development Could Potentially Lead to Diagnosis and Treatment in a Single Session

Breast cancer patients will receive faster treatment due to the development of a new, dedicated intra-operative magnetic resonance (MR) scanner which will enable doctors to carry out image-guided surgery as soon as problems are detected and diagnosed - possibly in a single out-patient session.
 
The innovative new technology is being developed by Specialty Magnetics Limited (a wholly owned subsidiary of Specialty Scanners plc) in collaboration with the Institute of Cancer Research (ICR) and the Science & Technology Facilities Council (STFC). This is the second MR scanner research and development project in which Specialty Magnetics Limited is collaborating with the ICR and the STFC.

Using conventional MR Imaging (MRI) systems, patients have to be removed from the scanner and the results analyzed before any surgical treatment can be conducted. But the new Intra-operative, Dedicated Breast MR Scanner being developed will allow image-guided surgery to take place in "real time" at the moment the problem is detected and diagnosed.

The new Intra-operative MR Scanner project will provide an excellent platform for treating tumors using non-invasive or minimally invasive ablation techniques such as focused-ultrasound or cryo-ablation leading - unlike in open excisional surgery - to less trauma, more breast tissue conservation, potentially no hospitalization and less anxiety and stress to women.

With one-in-nine women, on average, developing breast cancer at some point in their lifetime, this new technology could dramatically change the way breast cancer is diagnosed and treated and the patients are likely to see dramatic benefits. The new technology will enable the integration of image guided diagnostic and treatment procedures, seamlessly under one-roof, thereby shortening the women's pathway to treatment potentially, from several weeks and even months to one outpatient session.

"The Technology Strategy Board supports the research and development of technology and innovation that both increases economic growth and has the potential to improve quality of life,” said Iain Gray, chief executive of the Technology Strategy Board. “We are therefore delighted to support this project, which brings together the UK's world class expertise and has the potential to bring significant benefits to many thousands of patients."
"The ICR has a long history of interest and involvement in the breast cancer research and have also been involved in the collaborative technology development projects targeting breast cancer, said Prof. Martin Leach, director, Cancer Research UK Clinical MR Research Group, Institute of Cancer Research. “For instance, the UK wide MARIBS study -comparing the role of MR imaging (MRI) with the x-ray mammography (XRM) in the screening of a woman at high risk - was led by the ICR. Findings of this pioneering study led to the issue of the new, updated guidelines by the NICE recommending the use of MRI in the screening of high-risk women. Under the new NICE guidelines, the centres offering screening services should also be capable of performing MRI-guided biopsy procedures. As an Academic Partner, we believe we can contribute a great deal to the successful execution of many aspects of this project and looking forward to that opportunity."

"This is an highly exciting project and its successful execution will require the application of multi-disciplinary skills,” said Dr. Tom Bradshaw, Head of Cryogenics, Science & Technology Facilities Council.  “In that respect, the STFC is perhaps a rather uniquely placed organisation where many scientists and engineers with such a diverse range of skills - including expertise in cryogenics, robotics, display and materials technologies - are gathered in one location. There is consensus that in addition to the other form of cancer treatment options such as radio-therapy and chemo-therapy, the minimally invasive thermal ablation therapy method of cryo-ablation can play an important role in the management of many suitably selected group of patients. We also believe that MRI is the ideal modality for guiding the thermal ablation procedures and we are looking forward to the opportunity of making our own innovative contributions."

"We are extremely pleased that our wholly-owned subsidiary, Specialty Magnetics Limited will be, once again, working closely with the ICR and the STFC in another award winning project as a Lead and Industrial Partner. We value highly our now well- established links with these two highly eminent academic institutions,” said Dr. Ali Akgun, CEO, Specialty Scanners plc. “Our first collaboration has resulted in the creation of a truly dedicated and novel Breast MR Scanner, and I am confident that by bringing together their considerable expertise and resources these three partners will successfully execute this rather worthwhile project too. There is a great deal of interest in the availability of integrated, 'one-stop' Clinical Assessment & Treatment Service (CATS) Centres for cancer management and our Intra-operative MR Scanner project will help the Company to pioneer the construction of such a centre for breast cancer management and raise further the quality of care for women."

Higher Temperatures Yield Tunable, Supersensitive Hyper-CEST MRI

Standard magnetic resonance imaging, MRI, is a superb diagnostic tool but one that suffers from low sensitivity, requiring patients to remain motionless for long periods of time inside noisy, claustrophobic machines. A new MRI method, much faster, more selective -- able to distinguish even among specific target molecules -- and many thousands of times more sensitive, has now been developed by researchers at the Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley.

The key to the new technique is called "temperature-controlled molecular depolarization gates." It builds on a series of previous developments in MRI and the closely related field of nuclear magnetic resonance, NMR (which instead of an image yields a spectrum of molecular information), by members of the laboratories of Alexander Pines and David Wemmer at Berkeley Lab and UC Berkeley. Pines is the Glenn T. Seaborg Professor of Chemistry at the University of California at Berkeley and a senior scientist in Berkeley Lab's Materials Sciences Division. Wemmer is Professor of Chemistry at UC Berkeley and a member of Berkeley Lab's Physical Biosciences Division.

The technique was developed by a team led by Leif Schröder of Berkeley Lab's Materials Sciences Division, and including Lana Chavez, Tyler Meldrum, Monica Smith, and Thomas Lowery, all past or present members of the Pines and Wemmer labs; the researchers outline their results in the international edition of the journal Angewandte Chemie.

"The new method holds the promise of combining a set of proven NMR tools for the first time into a practical, supersensitive diagnostic system for imaging the distribution of specific molecules on such targets as tumors in human subjects," said lead author Schröder, "or even on individual cancer cells."

Laying the groundwork: hyperpolarization and cryptophane biosensors lead to Hyper-CEST MRI
MRI and NMR make use of the quantum-mechanical phenomenon known as nuclear spin; nuclei with odd numbers of protons or neutrons have net magnetic moment and will orient themselves like tiny bar magnets, spin "up" or spin "down," in a strong magnetic field. If the spinning nuclei are knocked off-axis by a jolt of radio-frequency (rf) energy, they wobble or precess at a characteristic rate, a rate that is strongly conditioned by their immediate chemical neighbors. During a certain relaxation time (typical of each atomic species in a specific environment), the nuclei reorient themselves and emit a radio signal that reveals both their position and their chemical surroundings.

The spin-up state requires fractionally less energy, so there's typically a slight excess of spin-up nuclei, about one in a hundred thousand (.001 percent), and it's this tiny difference that yields a useful signal. In clinical settings MRI is usually done using hydrogen nuclei, protons, which are ubiquitous in the human body. But other nuclear species, notably the noble gas xenon, offer advantages over hydrogen that in the case of xenon include a virtual absence of background signal, since there is no xenon in biological systems.

Xenon is particularly useful in MRI and NMR because the spins of its nuclei are readily polarized, in a process involving contact with rubidium vapor irradiated with a laser beam. In such "hyperpolarized" xenon, the excess of spin-up nuclei can be as much as 20 percent, which gives a far stronger signal than hydrogen's .001 percent spin-up excess. Moreover, hyperpolarized xenon has a much longer relaxation time than hydrogen.

Now add the ability to associate a single xenon nucleus with a specific molecular target, for example a protein or sugar on the surface of a cancer cell. To do this, the Pines and Wemmer labs have created biosensors equipped with cages that take up and hold onto xenon atoms; the cages, molecules called cryptophanes, are linked to ligands that target specific molecules of interest. Xenon biosensors engineered with several different ligands can be used at the same time; once in place, biosensors carrying hyperpolarized xenon can localize the MRI signals from a range of different molecules on the target.

The final advance underlying the new technique is called Hyper-CEST: hyperpolarized xenon chemical-exchange saturation transfer. While biosensors can bring the xenon to specific molecular targets, in realistic applications relatively few of these are present, only about one percent compared to the total amount of free xenon injected near that target. The signal from the polarized xenon inside the biosensor cages is consequently much fainter than that from the uncaged polarized xenon nearby.

"About 60 percent of the biosensor cages are filled with xenon," said Schröder, "but the problem is, you get only a tiny, broad NMR signal from the xenon when it is inside the cage. On the other hand, you have thousands of xenon nuclei just sitting around the cage."

The trick then is to depolarize the xenon nuclei in the immediate vicinity of the cages, which will serve to outline the target in high contrast against the surrounding hyperpolarized xenon pool. This is done through chemical exchange, as xenon atoms are constantly entering and leaving the biosensor cages.

A polarized xenon atom from the pool enters the cryptophane cage, which alters the xenon's resonance frequency, allowing it to be depolarized by rf radiation tuned to a specific frequency. The depolarized xenon atom is then exchanged for a new, incoming polarized atom and reenters the pool. In this way the buildup of nearby depolarized nuclei quickly outlines the target.

Because it produces a much stronger signal, Hyper-CEST acquires images thousands of times faster than would imaging the caged xenon directly. Yet it retains the great advantages of cryptophane biosensors, including their ability to "multiplex," or detect different targets at the same time.

"Slight differences in cage composition, involving only a carbon atom or two, affect the frequency of the signal from the xenon and produce distinct peaks in the NMR spectrum," says team member Tyler Meldrum, of the Materials Sciences Division. "If we design different cages for different xenon frequencies, we can put them all in at once and, by selectively tuning the rf pulses, see peaks at the frequencies corresponding to each kind of cage."

The final step
The processes described above -- hyperpolarizing the xenon, caging it in biosensors, and building up depolarized xenon in the immediate vicinity of the target through chemical exchange and selective bursts of rf radiation -- led to the development of Hyper-CEST MRI. But until now, Hyper-CEST MRI has only been tested at room temperature.

Using biosensor cages as temperature-controlled molecular depolarization gates makes Hyper-CEST MRI possible at a range of higher-than-room temperatures. Because the technique regulates the exchange rate of hyperpolarized-to-depolarized nuclei through the cages, biosensors regulated this way have been nicknamed "transpletors," by analogy to the transistors that act as gates for the flow of electrons from source to drain in electronic systems.

Hyper-CEST at a range of temperatures has many advantages. Most basic is that biomedical MRI must operate at body temperature. Aside from this practical consideration, temperature determines the rates at which different kinds of cryptophane-cage hosts react with their xenon-atom guests. And increasing temperature dramatically increases chemical exchange rates.

"At room temperature, a xenon atom will stay approximately 50 milliseconds inside the cage before it leaves again," says team member Monica Smith, of Berkeley Lab's Physical Biosciences Division. "Approaching body temperature, the time inside the cage decreases by at least factor of 10."

The ability to achieve high-contrast images, multiplexed to identify a range of molecular targets, and to do so in a short time, offers many benefits to patients and physicians.

"Doctors attempting to characterize tumors very often have to take biopsies, and that's painful for the patient, so they usually prefer to take only one biopsy," says Schröder. "But then they have to run all their tests on this very little tissue. So they would be happy with a method where you have a toolbox of sensors, you throw them all in and wait to let them bind, and then do your tests at the different frequencies and you see what sensors are present, detecting the different proteins. We showed that the exchange rate is so high at increased temperature that you can use a very selective rf pulse."

Enabling fast, sensitive, molecule-specific NMR and MRI in humans and other living subjects is perhaps the most evident advantage of the new technique, but possible applications don't end there. For example, the method offers a better way to study chemical exchange in nanostructures like zeolites, which are important in catalysis, or in versatile carbon nanotubes. Temperature-controlled depolarization is a breakthrough for NMR and MRI that will find uses in a variety of fields.

This research was supported by the Department of Energy's Office of Science, Office of Basic Energy Sciences; by the Deutsche Forschungsgemeinschaft; and by the University of California's Biotechnology Research and Education Program.

EVENT LISTINGS

Ecosystems Summit 2008 • Denver, Colo. • June 25-26

Ecosystems Summit 2008 is a solutions-packed two-day conference focused on the business opportunities for increasing sales and profits from the ecosystems of software, IT, electronics OEM and advanced technology companies. Today's leading technology companies are developing products and services to serve numerous specific solutions and platforms. To capitalize on the growth opportunities from these developments, you need to know how to become a key player in the ecosystems of strategic partner networks. Learn how to build your own web of lucrative ecosystem relationships and put the power of alliance and partner programs to work for you. You'll learn the best practices to take advantage of these market opportunities. Discover investment levels, time-to-revenue benchmarks, structuring the best deals and achieving maximum benefit from them by building your ecosystem programs to become revenue-generating growth engines.

www.ecosystemssummit.com

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