TECHNOLOGY LICENSING OPPORTUNITY: Multi-Channel Atomic Magnetometer (MCAM)

Unlike conventional multichannel atomic magnetometers that require one vapor cell and one optical system for each sensing channel, the patented Multi-Channel Atomic Magnetometer (MCAM) architecture from Los Alamos National Laboratory replaces many independent atomic magnetometers with a single shared vapor cell and optical system that simultaneously generates multiple independent sensing channels. MCAM is a non-cryogenic multi-channel optical quantum sensor in a single module that captures ultra-faint biomagnetic signals from the brain, heart and other sources with sensitivity approaching that of the cryogenic SQUID-based systems that have defined the field for decades. MCAM delivers that performance at roughly one-tenth the per-channel cost without a drop of liquid helium. The module pairs one large alkali-metal vapor cell with broad pump and probe laser beams read out by a photodiode array, providing 16 independent sensing channels in a single housing, scaling into helmet-style arrays of hundreds of channels, and flexing around the patient rather than forcing the patient into a fixed cryogenic dewar. Together, these attributes more easily allow for magnetoencephalography, magnetocardiography and magnetic-particle imaging while accelerating overall magnetic imaging workflows. Ongoing development is aimed at extending the sensing architecture from the centimeter scale characterized in the current prototype toward micrometer-scale spatial resolution, opening a path into cellular-scale magnetic imaging that current cryogenic and room-temperature arrays cannot address.

How it Works

The MCAM module operates on the spin-exchange relaxation-free (SERF) regime, in which atomic spins of alkali-metal atoms inside a large, sealed vapor cell are aligned by a circularly polarized broad pump laser beam through optical pumping and then interrogated by a linearly polarized broad probe beam propagating along a nearly parallel path. An external magnetic field of interest tilts the aligned atomic spins by an angle proportional to the field strength, and that tilt rotates the polarization plane of the probe beam through the Faraday effect; a photodiode array reads the optical rotation simultaneously at multiple points across the cell, with each photodiode pixel reporting on its own localized sensing volume. A buffer gas inside the cell restricts atomic motion so that the small cell volumes behind each pixel behave as independent sensing channels, a rear mirror folds the beams back through the cell to shorten the stand-off distance to the magnetic source, and transparent Pyrex wire heaters hold the cell at the operating temperature needed for SERF operation.

Technology Description

The patented shared-cell architecture generates multiple independent sensing channels from a single vapor cell, a single pump beam, a single probe beam, and a single detector array. A pair of broad, co-propagating laser beams, one for optical pumping and the other for probing, traverses the shared vapor cell to manipulate the internal atomic spins, converting the local magnetic field distribution into a spatially resolved optical signal that is read out by a multi-pixel photodetector. Because the buffer gas inside the cell restricts atomic diffusion, each pixel of the detector reports on its own small, spatially distinct region of the cell; therefore, the single module yields a two-dimensional map of the local magnetic field rather than a single-point measurement. Operation in the SERF regime, together with an integrated heating and shielding arrangement and a fold-back optical geometry that shortens the distance from the sensing volume to the magnetic source, sets the sensitivity floor in the low tens of femtotesla per root hertz at low frequency. A development path has been identified to reduce the effective sensing-volume scale from the roughly 1 cm per-channel footprint of the current prototype toward the 1 μm range, which would extend the platform from whole-organ mapping into micro-scale magnetic imaging regimes.

Architecturally, the MCAM module is engineered for arrays. Because all channels within a single module share one vapor cell, one laser pair, and one optics assembly, the per-channel parts count and tuning effort drop sharply versus designs that stack many single-channel sensors. Fiber-optic coupling between the laser sources and each sensor head lets modules be repositioned independently, so many modules can be tiled into a conformal helmet or surface array that adapts to head or torso shape and supports configurations that rigid large-cell predecessors cannot accommodate. The design is compatible with several alkali-metal and buffer-gas options and with per-module bias coils that allow each module to be tuned individually inside a larger array.

Advantages

• Development path toward micrometer-scale spatial resolution, a roughly four-order-of-magnitude improvement over the current centimeter-scale prototype and an enabler of cellular-scale magnetic imaging
• Sensitivity at the low tens of femtotesla per root hertz, comparable to cryogenic SQUID arrays, while using a warm vapor, non-cryogenic architecture
• Roughly tenfold per-channel cost reduction by sharing one vapor cell, one laser pair and one optics set across 16 channels
• No liquid cryogens, eliminating recurring cryogen costs and simplifying siting, maintenance and shielding
• Fiber-coupled, repositionable sensor heads that conform to the patient rather than forcing the patient into a fixed dewar
• Scalable into helmet-style arrays of hundreds of channels, including a size-adjustable pediatric configuration
• Shorter sensor-to-source stand-off via rear-mirror beam folding, sharpening spatial resolution of biomagnetic sources

Market Applications

• Medical Diagnostic Imaging (magnetoencephalography systems for epilepsy, stroke and neurodegenerative workups; magnetocardiography for arrhythmia and ischemia screening)
• Pediatric and Adaptive Neuroimaging (size-adjustable MEG helmets, point-of-care brain monitoring)
• Micro-scale Biomagnetic Imaging (single-neuron and small-circuit brain activity mapping, high-resolution cardiac tissue mapping)
• Cancer Diagnostics (magnetic nanoparticle imaging for tumor localization and targeted-therapy tracking)
• Magnetic Resonance Imaging (low-field/ultra-low field, portable MRI, functional brain imaging)
• Sensing (low-frequency antennas for underground or undersea links, geomagnetic surveying)
• Instrumentation (fundamental physics, biomagnetism laboratories, multichannel sensor R&D)

Development Status: TRL 4

U.S. Patent No. 11,105,865

LA-UR-26-25904

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