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Integrated Microchip Incorporating Atomic Magnetometer and Microfluidic Channel for NMR and MRI
Patent Number: 7,994,783
Abstract
This technology is a device that integrates a microfluidic channel and an alkali vapor cell on a microchip-like platform. In conjunction with a near resonant laser beam, the alkali vapor cell forms the basis for an atomic magnetometer, competing with (or even exceeding) the sensitivity of magnetometers based on superconducting quantum interference devices (SQUIDs). A variety of applications for such a device exist, most notably the detection of magnetic flux from a polarized sample of nuclei for the measurement of nuclear magnetic resonance (NMR) and magnetic resonance imaging. In an optimized system, the detection limit of this device is superior to that demonstrated by conventional inductive detection in a 300 MHz magnet. The device can be manufactured with conventional microfabrication techniques for ease of mass production. It can be widely applied in industry whenever trace amounts of chemical are being analyzed. For example, the pharmaceutical industry could use large arrays of these devices to perform parallel assays of a set of new trial drugs.
NEW ENABLING TECHNOLOGY
Nuclear magnetic resonance (NMR) is an essential technology for studying the physical, chemical and biological properties of various materials with applications in biomedical testing, chemical analysis and geology, among others.
Conventional NMR spectroscopy instruments are expensive, large, and require cryogenic cooling. By contrast, NIST’s highly compact integrated microchip, incorporating an atomic magnetometer and a microfluidic channel for NMR and MRI, requires no cryocooling and can be manufactured with conventional microfabrication techniques for ease of mass production.
Low field, low power, low noise
Demand for benchtop NMR that does not require cryogenic cooling has been increasing. Benchtop NMR is highly advantageous for chemists working in industrial laboratories. Compact and portable magnetic resonance imaging (MRI), also called battlefield MRI, has been demonstrated and holds the promise of making life-saving information available to doctors on the battlefield or in remote areas quickly. In both cases, more compact and less expensive NMR and MRI that do not require cryocooling will make these instruments increasingly available.
Low-field MRI is a growing area of interest that requires magnetometers to operate with high sensitivity at very low frequencies associated with low magnetic fields. This invention uses very small alkali vapor-cell atomic magnetometers with a sensitivity sufficient for detecting very weak DC magnetic fields produced by a small sample of fluid. The fabrication process allows for integration of the alkali vapor cell adjacent to a microfluidic channel within an integral microfluidic device.
Readily fabricated with existing technology and as accurate as cryocooled instruments.
Features
- Provides a means of NMR detection in magnetic fields near zero
- No cryogenics required
- Compact and portable
- Based on lithographic patterning, highly scalable
- Dimensions on the order of 1 mm
- Capable of detecting magnetization of 1 µl of water thermally polarized in a < 1 T field
- Detection limit superior to conventional inductive detection in a 300 MHz magnet
Applications/Industries
- Fluid flow imaging
- Identification and differentiation of chemical species with high selectivity
- Remotely detected NMR
The advantages of atomic magnetometers include: (1) sensitivity at low frequencies enabling detection at low magnetic fields and (2) chip-based implementation for low-cost production and multichannel designs.
Market
The device can be widely applied in industry and medicine whenever trace amounts of chemical are being analyzed. For example, the pharmaceutical industry could use large arrays of these devices to perform parallel assays of a set of new trial drugs.