FIELD

The present disclosure is directed to the area of covalently-bound anti-relaxation surface coatings. The present disclosure is also directed to methods, devices, and systems, such as magnetometers and magnetoencephalography systems and methods, that utilize these coatings.

BACKGROUND

In the nervous system, neurons propagate signals via action potentials. These are brief electric currents which flow down the length of a neuron causing chemical transmitters to be released at a synapse. The time-varying electrical current within an ensemble of neurons generates a magnetic field. Magnetoencephalography (MEG), the measurement of magnetic fields generated by the brain, is one method for observing these neural signals.

Existing technology for measuring MEG typically utilizes superconducting quantum interference devices (SQUIDs) or collections of discrete optically pumped magnetometers (OPMs). For MEG and other applications, the array of OPMS may have a large number of OPM sensors that are tightly packed. Such dense arrays can produce a high-resolution spatial mapping of the magnetic field, and at a very high sensitivity level. Such OPMs sensors can also be used for a wide range of other applications.

BRIEF SUMMARY

One embodiment is a magnetometer that includes a vapor cell having at least one wall, a chamber defined by the at least one wall, and alkali metal atoms disposed in the chamber to produce an alkali metal vapor in the chamber, wherein the at least one wall includes an oxide-containing interior surface; and an anti-relaxation coating disposed on the oxide-containing interior surface of the at least one wall of the vapor cell, wherein the anti-relaxation coating is a reaction product of the oxide-containing interior surface of the at least one wall with at least one mono- or dichlorosilane compound selected from:


wherein x, y, and z, when present, are each independently an integer in a range of 0 to 40.
In at least some embodiments, the at least one mono- or dichlorosilane compound includes



In at least some embodiments, the at least one mono- or dichlorosilane compound includes



In at least some embodiments, x, y, and z, when present, are each independently an integer in a range of 5 to 25. In at least some embodiments, x, y, and z, when present, are equal.

In at least some embodiments, the oxide-containing interior surface includes silicon dioxide. In at least some embodiments, the oxide-containing interior surface includes aluminum oxide. In at least some embodiments, the vapor cell includes quartz. In at least some embodiments, the vapor cell includes sapphire. In at least some embodiments, the vapor cell includes glass.

Another embodiment is a magnetic field measurement system that includes at least one of any of the magnetometers described above; at least one light source configured for directing light to the at least one magnetometer; and at least one detector configured to receive light that passes through the at least one magnetometer.

In at least some embodiments, the magnetic field measurement system further includes at least one magnetic field generator configured to produce a magnetic field at the vapor cell of the magnetometer. In at least some embodiments, the magnetic field measurement system further includes a computing device coupled to the at least one detector.

Yet another embodiment is a method of making any of the magnetometers described above. The method includes contacting the oxide-containing interior surface of the at least one wall of the vapor cell with the at least one mono- or dichlorosilane compound; and reacting the mono- or diclorosilane compound with the oxide-containing interior surface to form an anti-relaxation coating on the oxide-containing interior surface.

