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An NMR Chip The Size of a Seed

Together with a small permanent magnet, the chip could enable cheap NMR analysis in factories and clinics

2 min read
On the left, a silvery cylindrical magnet behind several brown spots and a penny. On the right, a blow up of one of the brown spots reveals a microscope image of a microchip.
Image: Dongwan Ha/Harvard SEAS

Engineers at Harvard University have made a nuclear magnetic resonance (NMR) spectroscopy chip so small you can hardly see it. It fits on a 2mm-by-2mm silicon chip and is the smallest NMR system built yet. The chip could lead to an ultra-compact, affordable NMR machine for spotting bacteria or cancer proteins in a doctors office or for quality control in drug and chemical production lines.

NMR spectroscopy reveals the chemical structure of organic molecules and is a common tool for studying proteins, discovering drug candidates, and for process and quality control in the petroleum and petrochemical industries. The technique involves aligning the nuclear spin of atoms along a static magnetic field and then vibrating them with a radio-frequency signal. At certain resonance frequencies that depend on the nucleus, the spins flip back and forth, producing an RF signal.

Conventional NMR requires large, expensive superconducting magnets to analyze the structure of complex molecules like proteins or to create high-resolution magnetic resonance imaging (MRI) scans. But smaller, less powerful permanent magnets suffice for probing smaller molecules.

High-quality permanent magnets have been shrinking, allowing researchers to combine them with compact spectrometer electronics for sensitive, high-resolution NMR. For instance, a different group at Harvard Medical School has made a palm-fitting NMR device for detecting tuberculosis, and another that attaches to a smartphone to detect tumor markers.

Now, Harvard electrical engineering and applied physics professor Donhee Ham and his colleagues have drastically shrunk the size of the electronics even further, fitting the RF receiver, transmitter and other components on a tiny seed-sized chip. The chip is used with a fist-sized permanent magnet to perform NMR. They reported the results in this week's Proceedings of the National Academy of Sciences.

The team was able to eliminate extra hardware needed when miniature permanent magnets are used for NMR. The problem with small permanent magnets is that the magnetic field fluctuates with small temperature changes. Resolving that typically requires hardware for physical thermal regulation. Instead, the researchers used signal-processing computations to estimate this fluctuation and compensate for it, explained Ham in a press release.

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Are You Ready for Workplace Brain Scanning?

Extracting and using brain data will make workers happier and more productive, backers say

11 min read
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A photo collage showing a man wearing a eeg headset while looking at a computer screen.
Nadia Radic
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Get ready: Neurotechnology is coming to the workplace. Neural sensors are now reliable and affordable enough to support commercial pilot projects that extract productivity-enhancing data from workers’ brains. These projects aren’t confined to specialized workplaces; they’re also happening in offices, factories, farms, and airports. The companies and people behind these neurotech devices are certain that they will improve our lives. But there are serious questions about whether work should be organized around certain functions of the brain, rather than the person as a whole.

To be clear, the kind of neurotech that’s currently available is nowhere close to reading minds. Sensors detect electrical activity across different areas of the brain, and the patterns in that activity can be broadly correlated with different feelings or physiological responses, such as stress, focus, or a reaction to external stimuli. These data can be exploited to make workers more efficient—and, proponents of the technology say, to make them happier. Two of the most interesting innovators in this field are the Israel-based startup InnerEye, which aims to give workers superhuman abilities, and Emotiv, a Silicon Valley neurotech company that’s bringing a brain-tracking wearable to office workers, including those working remotely.

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