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Magnetic fields provide a lower-power, more secure wireless body network

This is a prototype of the magnetic field human body communication, developed at UC San Diego, consists of magnetic-field-generating coils wrapped around three parts of the body, including the head, arm and leg (credit: Jacobs School of Engineering, UC San Diego)

A new wireless communication technique that works by sending magnetic signals through the human body could offer a lower power and more secure way to communicate information between wearable electronic devices than Bluetooth, according to electrical engineers at the University of California, San Diego.

While this work is still a proof-of-concept demonstration, researchers envision developing it into an ultra-low-power wireless system that can easily transmit information around the human body. One use would be a wireless sensor network for full-body health monitoring.

“In the future, people are going to be wearing more electronics, such as smart watches, fitness trackers and health monitors. All of these devices will need to communicate information with each other. Currently, these devices transmit information using Bluetooth radios, which use a lot of power to communicate. We’re trying to find new ways to communicate information around the human body that use much less power,” said Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at UC San Diego who led the study. Mercier also serves as the co-director of the UC San Diego Center for Wearable Sensors.

Bluetooth technology uses high-frequency electromagnetic radiation to transmit data; at those frequencies, radio signals do not easily pass through the human body, so they require a power boost to help overcome this signal obstruction, or “path loss.”

Lower power consumption

In this study, electrical engineers demonstrated a technique called “magnetic field human body communication” (mHBC), which uses the body as a vehicle to deliver magnetic energy between electronic devices. An advantage of this system is that magnetic fields are able to pass freely through biological tissues, so signals are communicated with much lower path losses and potentially, much lower power consumption.

In their experiments, researchers demonstrated that the magnetic communication link works well on the body, but they did not test the technique’s power consumption. However, the showed that the path losses associated with magnetic field human body communication are upwards of 10 million times lower than those associated with Bluetooth radios.

“This technique, to our knowledge, achieves the lowest path losses out of any wireless human body communication system that’s been demonstrated so far. This technique will allow us to build much lower power wearable devices,” said Mercier.

Lower power consumption also leads to longer battery life. “A problem with wearable devices like smart watches is that they have short operating times because they are limited to using small batteries. With this magnetic field human body communication system, we hope to significantly reduce power consumption as well as how frequently users need to recharge their devices,” said Jiwoong Park, a Ph.D student in Mercier’s Energy-Efficient Microsystems Lab at the UC San Diego Jacobs School of Engineering and first author of the study.

Human body communication schemes: (a) galvanic coupling using electric fields, (b) capacitive coupling using electric fields, and (c) the proposed magnetic resonant coupling scheme (credit: Jiwoong Park and Patrick P. Mercier)

The engineers presented their findings Aug. 26 at the 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Milan, Italy. In a forthcoming paper, they also compare their mHBC scheme to two earlier electric field human body communication (eHBC) schemes: galvanic coupling (using electric currents) and capacitive eHBC, also known as a wireless Body Area Network (using near-field radio frequencies); both have high path loss and other problems, they note.

Better security

The researchers also pointed out that this technique does not pose any serious health risks. Since this technique is intended for applications in ultra low power communication systems, the transmitting power of the magnetic signals sent through the body is expected to be many times lower than that of MRI scanners and wireless implant devices.

Another potential advantage of magnetic field human body communication is that it could offer more security than Bluetooth networks. Because Bluetooth radio communicates data over the air, anyone standing within 30 feet can potentially eavesdrop on that communication link. On the other hand, magnetic field human body communication employs the human body as a communication medium, making the communication link less vulnerable to eavesdropping. With this technique, researchers demonstrated that magnetic communication is strong on the body but dramatically decreases off the body. To put this in the context of a personal full-body wireless communication network, information would neither be radiated off the body nor be transmitted from one person to another.

“Increased privacy is desirable when you’re using your wearable devices to transmit information about your health,” said Park.

A proof-of-concept prototype

The researchers built a prototype to demonstrate the magnetic field human body communication technique. The prototype consists of copper wires insulated with PVC tubes. On one end, the copper wires are hooked up to an external analyzer and on the other end, the wires are wrapped in coils around three areas of the body: the head, arms and legs. These coils serve as sources for magnetic fields and are able to send magnetic signals from one part of the body to another using the body as a guide. With this prototype, researchers were able to demonstrate and measure low path loss communication from arm to arm, from arm to head, and from arm to leg.

Researchers noted that a limitation of this technique is that magnetic fields require circular geometries in order to propagate through the human body. Devices like smart watches, headbands and belts will all work well using magnetic field human body communication, but not a small patch that is stuck on the chest and used to measure heart rate, for example. As long as the wearable application can wrap around a part of the body, it should work just fine with this technique, researchers explained.

UPDATE Sept. 5, 2015 — ADDED (with illustration): In a forthcoming paper, they also compare their mHBC scheme to two earlier electric field human body communication (eHBC) schemes: galvanic coupling (using electric currents) and capacitive eHBC, also known as a wireless Body Area Network (using near-field radio frequencies); both have high path loss and other problems, they note.

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Lack of sleep connected to catching a cold, new research confirms

(Credit: iStock)

If you sleep six hours a night or less a night, you are 4.2 times more likely to catch a cold (five hours or less, 4.5 times more likely) compared to those who sleep more than seven hours in a night.

That’s the finding of a study by  Carnegie Mellon University’s Sheldon Cohen, the Robert E. Doherty University Professor of Psychology in the Dietrich College of Humanities and Social Sciences, and researchers from UC San Francisco and the University of Pittsburgh Medical Center.

Published in the journal Sleep, the researchers used objective sleep measures. For the study, 164 adults underwent two months of health screenings, interviews and questionnaires to establish baselines for factors like stress, temperament, and alcohol and cigarette use. The researchers also tracked their sleep patterns for seven days using a watch-like sensor that measured the duration and quality of sleep throughout the night.

Then, the participants were sequestered in a hotel, administered the cold virus via nasal drops and monitored for a week, collecting daily mucus samples to see if the virus had taken hold.

“Sleep goes beyond all the other factors that were measured,” Prather said. “It didn’t matter how old people were, their stress levels, their race, education or income. It didn’t matter if they were a smoker. With all those things taken into account, statistically sleep still carried the day and was an overwhelmingly strong predictor for susceptibility to the cold virus.”

Aric Prather, assistant professor of psychiatry at UCSF and lead author of the study, said the study shows the risks of chronic sleep loss better than typical experiments in which researchers artificially deprive subjects of sleep, because it is based on subjects’ normal sleep behavior. “This could be a typical week for someone during cold season,” he said.

Sleep should be treated as a crucial pillar of public health, along with diet and exercise, the researchers said.

Abstract of Behaviorally Assessed Sleep and Susceptibility to the Common Cold

Study Objectives:

Short sleep duration and poor sleep continuity have been implicated in the susceptibility to infectious illness. However, prior research has relied on subjective measures of sleep, which are subject to recall bias. The aim of this study was to determine whether sleep, measured behaviorally using wrist actigraphy, predicted cold incidence following experimental viral exposure.

Design, Measurements, and Results:

A total of 164 healthy men and women (age range, 18 to 55 y) volunteered for this study. Wrist actigraphy and sleep diaries assessed sleep duration and sleep continuity over 7 consecutive days. Participants were then quarantined and administered nasal drops containing the rhinovirus, and monitored over 5 days for the development of a clinical cold (defined by infection in the presence of objective signs of illness). Logistic regression analysis revealed that actigraphy- assessed shorter sleep duration was associated with an increased likelihood of development of a clinical cold. Specifically, those sleeping < 5 h (odds ratio [OR] = 4.50, 95% confidence interval [CI], 1.08–18.69) or sleeping between 5 to 6 h (OR = 4.24, 95% CI, 1.08–16.71) were at greater risk of developing the cold compared to those sleeping > 7 h per night; those sleeping 6.01 to 7 h were at no greater risk (OR = 1.66; 95% CI 0.40–6.95). This association was independent of prechallenge antibody levels, demographics, season of the year, body mass index, psychological variables, and health practices. Sleep fragmentation was unrelated to cold susceptibility. Other sleep variables obtained using diary and actigraphy were not strong predictors of cold susceptibility.

Conclusions:

Shorter sleep duration, measured behaviorally using actigraphy prior to viral exposure, was associated with increased susceptibility to the common cold.

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World’s most powerful, largest digital camera will image 37 billion stars and galaxies

The LSST’s camera will include a filter-changing mechanism and shutter. This animation shows that mechanism at work, which allows the camera to view different wavelengths; the camera is capable of viewing light from near-ultraviolet to near-infrared (0.3-1 μm) wavelengths. (credit: SLAC National Accelerator Laboratory)

The Department of Energy has approved the start of construction for a 3.2-gigapixel digital camera — the world’s largest — at the heart of the Large Synoptic Survey Telescope (LSST), revealing unprecedented details of the universe and helping unravel some of its greatest mysteries.

Assembled at the DOE’s SLAC National Accelerator Laboratory, the camera will be the eye of LSST.

Starting in 2022, LSST will take digital images of the entire visible southern sky every few nights from atop a high mountain called Cerro Pachón in Chile. It will produce a wide, deep, and fast survey of the night sky, cataloging by far the largest number of stars and galaxies ever observed.

During a 10-year time frame, LSST will detect tens of billions of objects and will create movies of the sky with unprecedented details.

In one shot, the Large Synoptic Survey Telescope’s 3.2-gigapixel camera will capture an area of the sky 40 times the size of the full moon (or almost 10 square degrees of sky). LSST’s large mirror and large field of view work together to deliver more light from faint astronomical objects than any optical telescope in the world. (credit: SLAC National Accelerator Laboratory)

The telescope’s camera — the size of a small car and weighing more than three tons — will capture full-sky images at such high resolution that it would take 1,500 high-definition television screens to display just one of them.

Components of the camera are being built by an international collaboration of universities and labs, including DOE’s Brookhaven National Laboratory, Lawrence Livermore National Laboratory and SLAC National Accelerator Laboratory. Building and testing the camera will take approximately five years.

This exploded view of the LSST’s digital camera highlights its various components, including lenses, shutter and filters. (credit: SLAC National Accelerator Laboratory)

SLAC is also designing and constructing the NSF-funded database for the telescope’s data management system. LSST will generate a vast public archive of data — approximately 6 million gigabytes per year, or the equivalent of shooting roughly 800,000 images with a regular 8-megapixel digital camera every night, albeit of much higher quality and scientific value. This data will help researchers study the formation of galaxies, track potentially hazardous asteroids, observe exploding stars, and better understand dark matter and dark energy, which together make up 95 percent of the universe but whose natures remain unknown.

The National Research Council’s Astronomy and Astrophysics decadal survey, Astro2010, ranked the LSST as the top ground-based priority for the field for the current decade. The recent report of the Particle Physics Project Prioritization Panel of the federal High Energy Physics Advisory Panel, setting forth the strategic plan for U.S. particle physics, also recommended completion of the LSST.

Funding for the camera comes from the DOE, while financial support for the telescope and site facilities, the data management system, and the education and public outreach infrastructure of LSST comes primarily from the National Science Foundation (NSF).