NMR-on-a-Chip's Magnetic Mini-Sensor Has Applications in Drug Development

The prototype chip device may have wide application as a sensitive chemical analyzer, for example, in rapid screening to find new drugs.

The technology was developed in collaboration between U.S. National Institute of Standards and Technology (NIST; Gaithersburg, MD, USA) and the University of California, Berkeley (CA, USA), and was described in the February 6, 2008 online issue of the Proceedings of the [U.S.] National Academy of Sciences (PNAS). The NMR chip detected magnetic signals from atomic nuclei in tap water flowing through a custom silicon chip that juxtaposes a tiny fluid channel and the NIST sensor. The Berkeley group recently co-developed this "remote NMR” technique for tracking small volumes of fluid or gas flow inside soft materials such as biologic tissue or porous rock, for possible applications in industrial processes and oil exploration. The chip could be used in NMR spectroscopy, a widely used technique for determining physical, chemical, electronic, and structural information about molecules. NMR signals are equivalent to those detected in magnetic resonance imaging (MRI) systems

Berkeley scientists selected the NIST sensor, a type of atomic magnetometer, for the chip device because of its small size and high sensitivity, which make it possible to detect weak magnetic resonance signals from a small sample of atoms in the adjacent microchannel. Detection is most effective when the sensor and sample are about the same size and located close together, according to lead author of the study, Dr. Micah Ledbetter. Thus, when samples are tiny, as in economic screening of many chemicals, a small sensor is crucial, according to Dr. Ledbetter.

Its small size and extreme sensitivity make the NIST sensor suitable for the microchip device, in contrast to SQUIDs (superconducting quantum interference devices) that require bulky equipment for cooling to cryogenic temperatures or conventional copper coils that need much higher magnetic fields (typically generated by large, superconducting magnets) such as those in conventional MRI.

The results reported in the PNAS demonstrated another use for the NIST mini-sensor, a spin-off of NIST's miniature atomic clocks. The sensor already has been shown to have biomedical imaging applications.

The lead investigator for the study was Dr. Alexander Pines, a leading authority on NMR. A joint university/NIST patent application is being filed for the microchip device.


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National Institute of Standards and Technology
University of California, Berkeley