# US 12,111,274 B1 · Device for detection of chemical properties of a sample using paramagnetic resonance

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- Number: US 12,111,274 B1
- Document ID: US12111274B1
- Status: Granted
- Kind: B1
- Application number: 18/467,635
- Filed: 2023-09-14
- Granted: 2024-10-08
- Earliest claimed: 2023-09-14
- Assignees: Paramagnetix, Inc.
- Applicants: Paramagnetix, Inc.
- Inventors: Nathan Newman; Saraansh Saxena; Tian Xue
- Web page: https://patentgrep.com/patent/US12111274B1

## CPC

- G01N 24/10: by using electron paramagnetic resonance (G01N24/12 takes precedence)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An electron paramagnetic resonant (EPR) instrument able to determine chemical properties of a sample using paramagnetic resonance is provided. In one embodiment, the instrument is able to measure the paramagnetic concentration of a wide variety of practical substances, ranging from food and beverages to biological specimens and solid-state electronic materials. The disclosed device can be portable and perform a measurement faster than commonly used techniques to quantify this parameter, including methods that use vibrating sample magnetometers and currently available electron paramagnetic resonance spectrometers.

## Claims

### Claim 1

A device for determining chemical properties of a sample, comprising:
a dielectric resonator comprised of a metallic chamber enclosure and a dielectric, both defining an opening configured to a sample to be moved through to a measurement position;
one or more permanent magnets configured to be positioned in a first position to create a condition in which the sample and resonant chamber are not in a paramagnetic resonance condition and further configured to be positioned in one or more different positions to create one or more conditions in which the sample and resonant chamber are in a paramagnetic resonance condition;
a microwave network vector analyzer configured to generate microwave radiation in the range of 1.0 GHz to 4.0 GHz and to receive and measure an amplitude and phase of reflected microwave radiation:
a magnetic-field coupling probe that is connected through one or more coaxial connectors and wires to the microwave vector analyzer and configured to couple the generated microwave radiation to the sample and resonant chamber:
a processor programmed with a set of computer-executable instructions, wherein when executed, the instructions cause the device to
measure a magnitude and phase of a reflected signal from the sample and resonant chamber;
measure a magnitude and phase reflected signal from a reference component or circuit;
determine a quality factor of the sample and resonant chamber when the sample is not in a paramagnetic resonance condition and when the sample is in one or more paramagnetic resonance conditions; and
from the measurements of the quality factor, determine at least one chemical property of the sample.

### Claim 2 (depends on 1)

The device of claim 1, wherein the dielectric comprises a dielectric constant between 65 and 140.

### Claim 3 (depends on 1)

The device of claim 1, wherein the resonator is less than 1.5″ in diameter and 0.95″ high and has an unloaded quality factor over 4,000 and a critically coupled quality factor over 2,000.

### Claim 4 (depends on 1)

The device of claim 1, wherein the processor is programmed to determine the sample's magnetic loss tangent from a change in quality factor between the sample and resonant chamber not in the paramagnetic resonance condition and in one or more of the paramagnetic resonance conditions.

### Claim 5 (depends on 1)

The device of claim 1, wherein the at least one chemical property of the sample is a concentration of one or more paramagnetic resonance species in the sample.

### Claim 6 (depends on 5)

The device of claim 5, wherein determining the concentration of one or more paramagnetic resonance species in the sample further comprises accessing a library or database containing data regarding one or more categories of samples, with each category associated with one or more measured magnetic loss tangents and one or more chemical properties of the sample, and comparing the data to assess the at least one chemical property.

### Claim 7 (depends on 1)

The device of claim 1 which is smaller than 24″×24″×18″.

### Claim 8 (depends on 1)

The device of claim 1 which is smaller than 10″×10″×8″.

### Claim 9 (depends on 1)

The device of claim 1 which is smaller than 7″×7″×4″.

### Claim 10 (depends on 1)

The device of claim 1, wherein the dielectric and at least one mechanical dielectric holder disposed within the metallic chamber enclosure of the dielectric resonator both have a paramagnetic concentration below 1018/cm3.

### Claim 11 (depends on 1)

The device of claim 1, wherein the dielectric and at least one mechanical dielectric holder disposed within the metallic chamber enclosure of the dielectric resonator both have a paramagnetic concentration below 1015/cm3.

### Claim 12 (depends on 1)

The device of claim 1, wherein the dielectric is made from TiO2 ceramics which contain additives totaling less than 5 atomic percent.

### Claim 13 (depends on 1)

The device of claim 1, wherein the magnetic-field coupling probe and the one or more coaxial connectors and wires are made completely from non-ferromagnetic materials.

### Claim 14 (depends on 11)

The device of claim 11, wherein the at least one mechanical dielectric holder is made from polylactic acid (PLA).

### Claim 15 (depends on 1)

The device of claim 1, wherein the at least one mechanical dielectric holder disposed within the metallic chamber enclosure of the dielectric resonator is made from plastic.

### Claim 16 (depends on 1)

The device of claim 1, wherein the magnetic-field coupling probe couples to an electromagnetic mode defined, at least in part, by the dielectric that concentrates a microwave magnetic field centrally in, below, and above a hole in an open region of the dielectric resonator, a volume where the sample resides, and an electric field at least in part contained within the dielectric.

### Claim 17 (depends on 16)

The device of claim 16, wherein the electromagnetic mode used to carry out the measurements is a fundamental mode of the dielectric.

### Claim 18 (depends on 16)

The method of claim 16, wherein the electromagnetic mode used to carry out the measurements is a TE01d fundamental mode of the dielectric.

### Claim 19 (depends on 1)

The device of claim 1, wherein determining the at least one chemical property of the sample is based on a sample magnetic loss tangent and further comprises determining a concentration of paramagnetic species in the sample based on its magnetic loss tangent.

### Claim 20 (depends on 1)

The device of claim 1, wherein the at least one chemical property of the sample is a safety of the sample for consumption or use, and a freshness of the food, including when the food is deemed undesirable or unsafe to eat.

### Claim 21 (depends on 1)

The device of claim 1, wherein the sample is one or more items selected from the group consisting of: fish, meat, fruit, nuts, milk, blood, and air.

### Claim 22 (depends on 1)

The device of claim 1, wherein the one or more permanent magnets comprise one or more ceramic iron-based magnet, one or more samarium cobalt-based magnet, one or more Alnico magnet, one or more Nd-based magnet, or a combination of these permanent magnets.

### Claim 23 (depends on 1)

The device of claim 1, further comprising a user interface or display configured to enable a user to select a type or category of sample to be evaluated by the device, and to display a result of the evaluation.

### Claim 24 (depends on 1)

The device of claim 1, further comprising a servo and shaft to enable the one or more permanent magnets to be moved into the first position and the one or more different positions.

### Claim 25 (depends on 1)

The device of claim 1, further comprising a source of irradiation configured to generate unpaired electrons in the sample.

### Claim 26 (depends on 1)

The device of claim 1, wherein the dielectric resonator operates at a frequency in the range of 1.0 to 2 GHz.