Systems and methods for characterizing fluids

Abstract

A system can include a magnet assembly including one or more first magnets. The system can include an inlet configured to receive a fluid sample from a source. The fluid sample can be configured to pass through the magnet assembly. The system can include a magnetic debris trap positioned downstream of the inlet and upstream of the magnet assembly. The magnetic debris trap can include a second magnet configured to capture magnetic debris from the fluid sample. The system can include an integrated circuit configured to execute a nuclear magnetic resonance pulse sequence and acquire a nuclear magnetic resonance signal corresponding to one or more characteristics of the fluid sample.

Description

Atty. Dkt. 098930-0432HU 10124 PC SYSTEMS AND METHODS FOR CHARACTERIZING FLUIDSCROSS-REFERENCE TO RELATED PATENT APPLICATION

[0001] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 776,910 filed on March 24, 2025, the entirety of which is incorporated by reference herein.GOVERNMENT RIGHTS

[0002] This invention was made with government support under DE-AR0001063 awarded by U.S. Department of Energy (DOE). The government has certain rights in this invention.TECHNICAL FIELD

[0003] The present application relates generally to nuclear magnetic resonance.BACKGROUND

[0004] Nuclear magnetic resonance (NMR) is widely used in many areas of chemical analysis for characterization of materials.SUMMARY

[0005] At least one aspect of the present disclosure is directed to a system. The system can include a magnet assembly including one or more first magnets. The system can include an inlet configured to receive a fluid sample from a source. The fluid sample can be configured to pass through the magnet assembly. The system can include a magnetic debris trap positioned downstream of the inlet and upstream of the magnet assembly. The magnetic debris trap can include a second magnet configured to capture magnetic debris from the fluid sample. The system can include an integrated circuit configured to execute an NMR pulse sequence and / or acquire an NMR signal corresponding to one or more characteristics of the fluid sample.

[0006] Another aspect of the present disclosure is directed to a method. The method can include providing a magnet assembly including one or more first magnets. The method can include receiving, by an inlet, a fluid sample from a source. The method can include capturing, by a magnetic debris trap positioned downstream of the inlet and upstream of the magnet assembly, magnetic debris from the fluid sample. The method can include passing the14907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC fluid sample through the magnet assembly. The method can include executing, by an integrated circuit, an NMR pulse sequence. The method can include acquiring, by the integrated circuit, an NMR signal corresponding to one or more characteristics of the fluid sample and responsive to executing the NMR pulse sequence.

[0007] Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices and / or processes described herein, as defined solely by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

[0009] FIG. 1 A illustrates an NMR sensor, according to an embodiment.

[0010] FIG. IB illustrates an NMR signal.

[0011] FIG. 2 illustrates an NMR spectrum for an ethanol sample.

[0012] FIG. 3 A shows the1H NMR spectra of two mineral oil samples.

[0013] FIG. 3B shows the1H NMR spectra between 5 and 8 ppm of the two mineral oil samples of FIG. 3 A.

[0014] FIG. 4 illustrates a T2 measurement obtained by a pulse sequence using the NMR sensor for oil samples.

[0015] FIG. 5 illustrates an integrated circuit, according to an embodiment.

[0016] FIG. 6 illustrates a system, according to an embodiment.

[0017] FIG. 7 illustrates a method of characterizing fluids, according to an embodiment.

[0018] Like reference numbers and designations in the various drawings indicate like elements.DETAILED DESCRIPTION24907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0019] Following below are more detailed descriptions of various concepts related to, and implementations of, methods, apparatuses, and systems for characterizing fluids. The various concepts introduced above and discussed in greater detail below may be implemented in any of a number of ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

[0020] NMR signals can be obtained from NMR spectrometers. NMR spectrometers can include equipment (e.g., hardware) such as magnets to produce a static magnetic field, radiofrequency (RF) electronics to generate pulses of RF magnetic fields, and gradient electronics to produce pulses of direct current (DC) magnetic fields and gradients. The operation of this hardware, in concert, can produce signals originating from the hydrogen atoms in the samples. The signal can be processed to obtain information about the materials.

[0021] The magnetic resonance (MR) phenomenon can include the application of magnetic fields to an object that impacts the magnetic moment (e.g., spin) of an atom in the object. The magnetic field can cause the spin of the atoms in the object to align along and oscillate (e.g., precess) about the axis of the applied magnetic field. The precession frequency can be indicative of the molecular moieties and the molecular structure. The spin magnetization of the atoms can be measured. Relaxation can include the return to equilibrium of this magnetization. For example, longitudinal relaxation due to energy exchange between the spins of the atoms and the surrounding lattice (e.g., spin-lattice relaxation) can be denoted by a time Ti when the longitudinal magnetization has returned to a predetermined percentage (e.g., 63%) of its final value. Longitudinal relaxation can involve the component of the spin parallel or antiparallel to the direction of the magnetic field. Transverse relaxation that results from spins getting out of phase can be denoted by time T2 when the transverse magnetization has lost a predetermined percentage (e.g., 63%) of its original value. The transverse relaxation can involve the components of the spins oriented orthogonal to the axis of the applied magnetic field. The T2 measurement can be performed using the spin-echo pulse sequence, which can involve a 90-degree pulse followed by one 180-degree refocusing pulse. The T2 can be measured using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence, which can use an initial 90-degree excitation pulse followed by a series of 180-degree (pi) pulses.

[0022] The NMR signals, frequencies, and relaxation times can be affected by various physical phenomena of the molecular structures and molecular dynamics. The phenomena 34907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC can include spin-lattice relaxation, spin-spin relaxation, and molecular diffusion of the molecules. Spin-lattice relaxations can be characterized by time constant, Ti. Spin-spin relaxations can be characterized by time constant, T2. The diffusion can be characterized by the diffusion constant, D. These parameters can be measured using NMR systems based on superconducting magnets. However, these superconducting systems can be large and expensive, thus limiting their broad applications.

[0023] Small-size NMR systems can utilize miniaturized electronic components to reduce the size and weight of the system compared to NMR systems based on superconducting magnets. However, implementing such a system in and around a working industrial site (e.g., chemical plant, refinery, power plant, electrical grid facility) can present additional challenges from the specific environment. For example, the system may be outdoors and therefore subject to large temperature variations daily and / or seasonally and due to the particular geographic environment. High-power electrical equipment can emit electromagnetic interference, which may adversely impact the operation of the NMR system. The NMR system may be exposed to vibrations at the industrial site, which could impact the NMR measurements on the fluid. The industrial site may have a fluid (e.g., industrial fluid, processing fluid) that would be desirable to characterize. However, the fluid may be conveyed through pipes containing contaminants, which could interfere with the process of making NMR measurements on the fluid. For example, the contaminants could be captured by the magnets of the NMR system and subsequently clog the flow of the fluid through the NMR system.

[0024] The systems and methods of the present disclosure, in some embodiments, relate to an NMR sensor configured to operate in the vicinity of industrial equipment and that can acquire NMR signals to characterize the properties of fluids. The NMR sensor of the present disclosure can overcome challenges associated with characterizing the properties of fluids in an industrial or other setting.

[0025] FIG. 1 A illustrates an NMR sensor 100. The NMR sensor 100 can include one or more first magnets 105 and / or one or more NMR coils 110. The NMR sensor 100 can receive one or more samples 115.

[0026] The one or more first magnets 105 can provide a static magnetic field for the NMR sensor. The one or more first magnets 105 can include a plurality of permanent magnet blocks. The one or more first magnets 105 can be arranged in a Halbach array (e.g., a44907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC Halbach array cylinder). In this array, multiple permanent magnet blocks can be arranged such that the magnetization orientation is sin(phi) where phi is the azimuthal angle. In the Halbach array, the magnetic field can be focused in the middle of the cylinder and the field outside the cylinder is very low (e.g., negligible compared to the magnetic field inside the cylinder). The one or more first magnets 105 of the Halbach array cylinder can have magnetic field uniformity.

[0027] Alternatively, the one or more first magnets 105 can be arranged in a geometry different from the Halbach array cylinder. For example, the one or more first magnets 105 can be arranged as a parallel-plate magnet with a soft iron yoke.

[0028] NMR can directly detect the hydrogen or other NMR active atoms in a fluid sample. When a fluid is placed in a magnetic field, the nuclear spins of the hydrogen atoms can be polarized along the applied magnetic field. RF pulses applied to the sample 115 initiate Larmor precession which then induces an NMR signal in the NMR coil 110 as an electrical voltage as shown in FIG. 1 A. The amplitude of the signal can be proportional to the number of hydrogen atoms in the sample 115. Thus, NMR can be used to quantify the hydrogen-containing materials. The frequency spectrum of this signal can reveal multiple peaks at slightly different frequencies (e.g., on the order of parts per million) due to the different molecular moieties and structures. This signal can gradually decay due to spin-spin interactions (as shown in FIG. IB) with a time constant called T2, reflecting the dynamics of the molecules and their interaction with the environment. NMR can elucidate the structure and dynamics of molecules at atomic resolution.

[0029] NMR properties of materials can include the frequency spectrum, spin-lattice relaxation time (Ti), spin-spin relaxation time (T2), and diffusion coefficient (D). Each property can be measured by specific pulse sequences and NMR experiments.

[0030] A method for obtaining frequency spectrum measurements can include the free-induction-decay (FID) method. This method can use the following pulse sequence described in Equation 1 :RD -p90 -ACQ (1)

[0031] The first time period RD can be long (e.g., a few seconds, several times of Ti of the sample) for the system to recover to thermal equilibrium. The p90 pulse can rotate the spin magnetization to the transverse plane to produce an NMR signal to be detected during the time period, ACQ. The detected signal can then be Fourier transformed to obtain the54907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC frequency spectrum. The frequency axis can be rescaled to chemical shift (CS) which is defined as Equation 2:CS = (f-fo) / fo, (2) where f is the frequency of the NMR spectrum, and fo is the frequency of the reference signal. The reference signal can be determined by the hydrogen NMR frequency of tetramethylsilane (TMS, Si(CHs)4). Because the CS can be small, the CS axis can be displayed in ppm (part-per-million).

[0032] FIG. 2 illustrates an example NMR spectrum for an ethanol sample. The horizontal axis is the chemical shift in ppm. The numbers (1,2,3) marked the three hydrogen atoms in the ethanol molecule.

[0033] Such a spectrum can be used to determine the magnetic field. For example, if the CS of the particular molecule of the test is known, for example, for water, CSw= 4.7 ppm. Thus, the magnetic field can be determined as B0=fw / g(l+CSw), where fwis the water signal frequency, and g is the gyromagnetic ratio of hydrogen which is 4.257x107Hz / T.

[0034] Mineral oil is widely used in many industries for lubrication, electrical insulation, dissolution, heat conduction, and cooling. It is typically made from the distillation of petroleum crude oils. The majority of the oil molecules are saturated hydrocarbon alkanes. Other molecules are also present, such as aromatics and molecules with double and triple bonds (e.g., alkenes and alkynes). Examples of the NMR spectrum of mineral oils are shown in FIGS. 3A and 3B. Sample 1 is a fresh mineral oil and Sample 2 is a mineral oil sample that has been subject to high temperatures. As a result, the NMR spectrum of such oils shows a dominant signal of chemical shift in the range of 0-2 ppm corresponding to CH3- (methyl) and CH2 (methylene) groups, as shown in FIG. 3 A. FIG. 3 A shows the1H NMR (e.g., proton NMR, protium NMR, hydrogen- 1 NMR) spectra of two mineral oil samples, fresh (Sample 1) and heat-treated (Sample 2). The 'HNMR spectra can display peaks representing chemical shifts of each analyte proton. FIG. 3B shows an enlarged display of the chemical shift range of 5-8 ppm in FIG. 3 A, which shows the additional peaks that correspond to aromatic hydrogens (e.g., hydrogen atoms directly bonded to a carbon atom in an aromatic ring system) and changes due to heat treatment.

[0035] As shown in FIG. 3 A, the spectra are dominated by the large peaks around 0-2 ppm corresponding to the methyl and methylene groups. FIG. 3B shows several peaks in the chemical shift range of 5-8 ppm which are typically due to the aromatic molecules in the64907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC mineral oil. Thus, these changes in the peak height and peak shapes indicate the changes in the mineral oil composition likely due to its exposure to high temperatures during the sample preparation. In addition, a signal at around the chemical shift of 4 ppm may indicate the presence of water in the oil which can be important for the electrical property of such oils. For example, the presence of water could be a strong indication of the degradation of the oil composition and the dielectric insulation capability of the oil.

[0036] Different methods can be used to obtain Ti. For example, the Ti measurement can be obtained using the inversion-recovery (IR) method and saturation-recovery (SR) method. For the IR method, the pulse sequence can be described as Equation 3:RD - pl80 - WT - p90 - ACQ (3)

[0037] Here, the first time period RD can be long (e.g., several times of Ti of the sample) for the system to recover to thermal equilibrium. The pl 80 pulse can invert the magnetization. The time WT can allow the magnetization (M) to relax according to Equation 4:M(WT) = M0{l - 2 exp [-L J where Mo is the equilibrium magnetization of the sample. The magnetization can be measured after the data acquisition (ACQ) after the p90 pulse. Several measurements of the signal for a series of values of WT can be obtained to determine the Ti of the sample.

[0038] Furthermore, imaging pulse sequences combining RF pulses and gradient pulses can be applied after the WT in Equation 1 to produce MRI images. In this case, Equation 2 can be applied to each voxel of the image. When several images with different WT are obtained, it is possible to obtain TI for each and all voxels in order to obtain a spatial map of Ti of the sample.

[0039] In the SR method, the pulse sequence can be described as Equation 5:WT - p90 - ACQ (5)

[0040] Here it can be assumed that the magnetization at the beginning of the WT period is zero due to the saturation in the previous experiment or by additional pulses to saturate. The magnetization can recover during the time WT according to Equation 6:WT1 M(VFT) = MO{1 - exp74907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0041] Similar to the IR method, the imaging method and pulse sequences can be added to obtain an image of the sample.

[0042] For the measurement of T2, a spin-echo pulse sequence can be used, which can be described in Equation 7:RD - p90 - TE / 2 - p 180 - TE / 2 - ACQ (7)

[0043] Here the time period TE can be defined as echo time. The time spacing between the p90 and pl 80 is half TE (e.g., TE / 2). The magnetization can decay as a function of TE according to Equation 8:TE MITE) = Moexpwhere Mo is the magnetization when TE / T2 approaches 0. Similar to the Ti measurement described above, when several measurements with different TE are obtained, the value of T2 of a sample can be obtained.

[0044] In addition to the spin-echo sequence, the CPMG sequence can be used with multiple pl 80 pulses to generate a train of echoes. The echo time for echo number n is n*TE. For example, for the first echo, n = 1 and for the 10thecho, n = 10. As a result, with one experiment, several data points of the signal decay can be obtained and thus accelerate the measurement of T2.

[0045] FIG. 4 illustrates a T2 measurement obtained by the CPMG pulse sequence using the NMR sensor 100 for 4 oil samples (e.g., light oil, medium oil, medium -heavy oil, heavy oil). The light oil sample shows a slow decay rate with a T2 of approximately 0.5 s. In contrast, the heavy oil sample exhibits a much faster decay with T2 of a few milliseconds. The heavy oil sample can have a density that is greater than the density of the light oil sample, the medium oil sample, and the medium-heavy oil sample. The medium-heavy oil sample can have a density that is greater than the density of the light oil sample and the medium oil sample. The medium oil sample can have a density that is greater than the density of the light oil sample.

[0046] The property of molecular diffusion can reflect the molecular composition as well as the physical and fluidic environment. For example, when a water molecule is in a viscous fluid, its diffusion coefficient (D) can decrease. When fluid is inside porous materials or tissues, water diffusion can be restricted due to the presence of solid materials or84907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC membranes. The diffusion coefficient can be lower than the value in the bulk fluid. As a result, the measurement of the diffusion coefficient can be used to characterize porous materials and tissue microstructure.

[0047] Diffusion can be measured using a spin-echo sequence with additional field gradient pulses during the two time periods, first between the p90 and pl 80 and second between pl 80 and ACQ. The magnetization decay due to diffusion can be described in Equation 9:M(b) = MQ exp [—&£)], (9) where D is the diffusion coefficient, and b is the diffusion weighting determined by the pulse sequence and in particular the field gradient pulses used. Similar to the Ti and T2 measurements, several signals with different b values can be obtained to determine D.

[0048] All the measurements described above, including relaxation and diffusion, can be performed by acquiring the NMR spectrum during the data acquisition period (ACQ). Thus, the dynamics of all hydrogen atoms (as represented by the peaks) can be determined. It can be important to achieve a high resolution of the NMR spectrum to identify each peak.

[0049] Small-sized systems based on permanent magnets and miniaturized electronics can be used to perform NMR measurements. However, because the magnetic field of such magnets is sensitive to the magnet temperature, the frequency of the NMR signal can change as the magnet temperature drifts. As a result, the multiple scans of the NMR signals can appear as a spectral broadening and thus can degrade the spectral resolution. Such frequency drift can be corrected by the systems and methods of the present disclosure.

[0050] FIG. 5 illustrates an integrated circuit 505 (e.g., NMR integrated circuit). The integrated circuit 505 can include a pulse sequence generator 510 (e.g., generator), a transmitter 515 (e.g., radio frequency transmitter, low-power RF transmitter, transmitter circuit), a receiver 520 (e.g., radio frequency receiver, low noise RF receiver, receiver circuit), and one or more controllers 525.

[0051] The pulse sequence generator 510 can synthesize pulse sequences (e.g., NMR pulses sequences) with precise frequency, duration, phase, and amplitude control. The pulse sequence can include the CPMG sequence. The output RF pulses of the pulse sequence generator 510 can be of low power, such as 1 mW (often called 0 dBm), or they can be higher (e.g., 100 mW). For small detection samples, this low power can be sufficient. To manipulate spins in a large sample, stronger RF pulses can be used. This can be achieved by feeding the 94907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC RF pulses from the pulse sequence generator 510 into the transmitter 515 that amplifies the low-power pulses to a higher power (e.g., 10 W to a few kW) while maintaining the RF phase, frequency, and duration. The execution of the pulse sequence can create an NMR signal in the NMR coil 110 that is detected by the receiver 520. The receiver 520 can include a pre-amplifier, a variable gain amplifier, phase detectors, a demodulator, and filters. The received signal can be digitized using analog-to-digital converters (ADC) and can be analyzed by a computer, or micro-processors.

[0052] Application Specific Integrated Circuits (ASICs) can encapsulate NMR-relevant circuitry in an integrated circuit. Such NMR ASICs can include the pulse sequence generator 510, the receiver 520, and the transmitter 515. These integrated circuits can allow for a reduction of the size of NMR electronics and result in miniaturized NMR systems. Furthermore, modern semiconductor production processes such as Silicon-on-Insulator (SOI) process can be used to reduce parasitic device capacitance, lower leakage currents and thus improve high-temperature performance. Thus, the implementation of NMR ASIC on SOI can allow for downhole NMR electronics at temperatures up to 200°C or higher.

[0053] The one or more controllers 525 can include a microcontroller. The microcontroller can include SM320F28335-HT, TMS320F2833x series from Texas Instruments, or CPU chips (e.g., Cortex processors based on the ARM architecture), or FPGA (e.g., Artix-7 family by Xilinx and XEM8320 to handle the communication between the NMR sensor 100 and the control equipment (e.g., data management computer) to send commands to the sensor electronics and NMR ASIC and to transfer their data. Various serial communication protocols can be used for these communications, such as CAN bus, SPI, RS485, RS232, USB and ethernet. Wireless protocols, such as Bluetooth and WiFi (e.g., based on the IEEE 802.11 family of standards), may be used for communications. The security of the sensor data can be protected via encryption methods and security protocols such as HTTPS and SNEP (Secure Network Encryption Protocol) to maintain data confidentiality and authentication.

[0054] FIG. 6 illustrates a system 600. The system 600 can include a magnet assembly 605, an inlet 610, a magnetic debris trap 615, the integrated circuit 500, and an outlet 625. The magnet assembly 605 can include the one or more first magnets 105 described with respect to FIG. 1 A.104907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0055] The magnet assembly 605 can be part of an NMR probe. The NMR probe can be configured to analyze the sample 115. The NMR probe can draw the sample 115 to the magnet assembly 605 to perform NMR measurements. A pressure compensation system can be built into the NMR probe for high-pressure capabilities.

[0056] The inlet 610 can receive the sample 115. The sample 115 can include a fluid sample. The inlet 610 can receive the fluid sample from a source 612 (e.g., fluid reservoir). The source 612 can include a main flowline 603 (e.g., a flowline for industrial processing). The fluid sample can pass through the magnet assembly 605. For example, the fluid sample can flow through the magnet assembly 605. The sample 115 can enter the NMR probe from the inlet 610. One or more control valve can be used to control the entry of the sample 115 into the NMR probe. The one or more controllers 525 can control the control valve. The control valve can be configured to control flow of the fluid sample from the source 612 to the magnet assembly 605.

[0057] The magnetic debris trap 615 can be positioned downstream of the inlet 610. The magnetic debris trap 615 can be positioned upstream of the magnet assembly 605. The magnetic debris trap 615 can include a second magnet 620. The second magnet 620 can include a neodymium magnet (NdFeB) or other hard magnetic material. The second magnet 620 can capture magnetic debris from the fluid sample. The magnetic debris trap 615 can include a plug 613 (e.g., strainer plug). The plug 613 can be removed from the magnetic debris trap 615 to clean the magnetic debris trap 615. For example, the plug 613 can be removed to clean the second magnet 620. The plug 613 can be removed from the magnetic debris trap 615 to access the magnetic debris in the magnetic debris trap 615 that has been separated from the fluid sample. The plug 613 can be removed from the magnetic debris trap 615 for cleaning and maintenance. When industrial fluids are conveyed through metal pipes, they may contain contaminants such as metal debris, rust particles, sand particles, and / or organic solid particles. The debris particles that are magnetic (e.g., the magnetic debris), can be captured by the magnetic debris trap 615. The magnetic debris trap 615 can capture the magnetic debris before the sample 115 reaches the NMR sensor 100.

[0058] The integrated circuit 500 can be configured to execute an NMR pulse sequence. The NMR pulse sequence can include a timed set of RF pulses, delays, and gradients that are applied to the sample 115 in a magnetic field to generate an NMR signal.114907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0059] The integrated circuit 500 can be configured to acquire the NMR signal corresponding to one or more characteristics of the fluid sample. The integrated circuit 500 can acquire the NMR signal subsequent to executing the NMR pulse sequence.

[0060] In some embodiments, the system 600 can include thermal insulation. The thermal insulation can be positioned around the magnet assembly 605. The thermal insulation can include at least one of foam, fiberglass, glass wool, reflective thermal aluminum foil, or metalized mylar film. The one or more controllers 525 of the integrated circuit 500 can be configured to determine a Larmor frequency of the system 600. The one or more controllers 525 can be configured to adjust a frequency of the system 600 to the Larmor frequency. The one or more controllers 525 can be configured to calibrate the frequency of the system 600 to address temperature variations in the system 600. The thermal insulation can minimize the rate of temperature drift of the magnet assembly 605. When the temperature drift is reduced, the Larmor frequency change can be slowed and can be tracked by measuring the temperature of the magnet assembly 605 and updating the spectrometer frequency immediately prior to performing NMR experiments.

[0061] The system 600 can include one or more approaches to regulating magnet temperature or minimizing the temperature drift. For example, temperature sensors and heaters can be installed on the magnet assembly 605. A temperature controller can be used to measure and control the temperature of the magnet assembly 605. In another example, thermal insulating materials can be installed around the magnet assembly 605 to reduce heat transfer between the magnet assembly 605 and the environment. This can decrease the rate of the temperature change of the magnet assembly 605. Multiple layers of the thermal insulating materials could further enhance the insulation. In yet another example, before the execution of the desired NMR experiment, an additional NMR experiment, such as FID (Eq. 1) can be performed to determine the Larmor frequency of the system 600. Then, the frequency of the NMR sensor 100 can be adjusted to the current Larmor frequency immediately prior to performing the desired NMR experiment. In yet another example, the NMR Larmor frequency can be determined from the prior NMR experiment (e.g., FID or CPMG) by analyzing the FID or echo signal. Then the frequency of the system 600 can be adjusted to the current Larmor frequency prior to performing the next experiment. In yet another example, thermal insulation can be combined with temperature regulation to achieve improved temperature stability and reduce power requirements.124907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0062] The outlet 625 can output the fluid sample to the source 612. For example, the outlet 625 can output the fluid sample to the source 612 subsequent to the fluid sample passing through the magnet assembly 605. The outlet 625 can fluidically couple the inlet 610 with the source 612. The sample 115 can exit the NMR probe to the outlet 625. The sample 115 to be returned to the source 612 via the outlet 625. The one or more control valves can be used to control the exit of the sample 115 from the NMR probe. The one or more control valves can allow for fluid sampling using a pressure gradient, such that a pump may not be needed to move the fluid.

[0063] In some embodiments, the magnet assembly 605 and the integrated circuit 500 are positioned in a housing 630, and the magnetic debris trap 615 is positioned exterior to the housing 630, as shown in FIG. 6. Alternatively, in some embodiments, the magnet assembly 605, the integrated circuit 500, and at least a portion of the magnetic debris trap 615 are positioned in the housing 630. The housing 630 can enclose the magnet assembly 605, and / or the integrated circuit 500. One or more components of the system 600 can be positioned in the housing 630.

[0064] The housing 630 can be coupled with a vibration-isolation device. For example, the NMR sensor 100 may be exposed to vibration at an installation site due to surrounding equipment (e.g., motors, road traffic, electrical instruments, and heavy machinery). Without the vibration isolation device, such vibrations can be transmitted to the NMR sensor 100 through the mechanical support of the NMR sensor 100 and through the fluid connections. To reduce the vibration, the NMR sensor 100 may be mounted on a stable stand away from such vibration-generating devices and may use one or more vibrationisolation devices (e.g., rubber feet, foams, and vibration isolation mounts). Pipe supports can be used to reduce the vibration from the fluid connections. Dampening the pipe vibrations can be effective using viscous dampeners, visco-elastic dampeners, and routing the pipes through lossy materials such as sand and rubber.

[0065] In some embodiments, the system 600 can include a channel (e.g., auxiliary flowline 602, pipe, hollow cylinder). The channel can be made of a material inert to the fluid sample. For example, the channel can include a chemically inert flowline. The channel can be made of a material that allows NMR signals to be detected, but does not significantly alter the NMR signals. The channel can be coupled with the inlet 610 and / or the outlet 625. The channel can be disposed in the housing 630. A coil of copper wires (e.g., NMR coil 110) can be wound exterior to the channel to detect the NMR signal of the sample inside the channel.134907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC The channel can be configured to withstand the pressure of the sample. The channel can be configured not to react with the sample. The channel can be configured not to absorb the sample. The channel can be a glass tube, a sapphire tube, a ceramic tube, a machined polyetheretherketone (PEEK) tube, or an extruded PEEK tube. The channel can be positioned inside a steel chamber to further protect the channel and / or to avoid sample leakage in case the channel is damaged. Without the magnetic debris trap 615, the channel can become clogged due to magnetic particles being captured by the magnet assembly 605.

[0066] In some embodiments, the system 600 can include a pump. The pump can be configured to convey the fluid sample from the source 612 to the magnet assembly 605. For example, the fluid sample can enter the NMR probe from a first end. A second end of the NMR probe can be connected to the pump. The pump can withdraw fluid from the 612 and into the NMR probe. The pump can include a piston pump. The piston pump can withdraw fluid into the NMR probe for measurements. After the measurement is performed, the piston pump may push the fluid out of the NMR probe. After the fluid is pushed out of the NMR probe, the NMR probe can be ready for the next sample. In this example, the NMR probe can have a single entry point for the sample.

[0067] When the NMR sensor 100 is installed in the field, the nearby equipment may cause electromagnetic interferences. In particular, the instrument that draws and processes a large amount of electrical power (often high voltage and high current) can produce significant electric fields and magnetic fields at the NMR sensor 100. The electric fields can cause noise in NMR measurements by interfering with the NMR electronics and introducing unstable voltages. The magnetic fields produced by both AC and DC currents can alter the magnetic field at the NMR sensor 100 and substantially degrade the measurements. Furthermore, large solid ground planes used in PCB design can cause eddy currents due to magnetic field fluctuations. The solid ground plane in the PCB design can be removed and the non-looping ground can instead be used.

[0068] To address these issues, the system 600 can include a metallic shield 632. The metallic shield 632 can be configured to reduce interference from electric fields and magnetic fields. The metallic shield 632 can shield against interference from high-frequency magnetic fields. For example, the high-frequency magnetic fields can have a frequency in a range of 100 kHz and 300 GHz. Shielding these interfering fields around the magnet assembly 605 and the electronics (e.g., PCBs) can be done by installing one or more shields (e.g., metallic shields) around the system 600 to reduce noise. For example, metallic sheets can be used to 144907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC shield against the electric fields and high-frequency magnetic fields. The housing 630 can enclose the metallic shield 632.

[0069] In some embodiments, the system 600 can include a magnetic shield 634. The magnetic shield 634 can be configured to reduce interference from magnetic fields. The magnetic shield 634 can shield against low-frequency magnetic fields. For example, the low-frequency magnetic fields can have a frequency in a range of 1 Hz and 100 kHz. Silicon steel, mu-metal and / or ferrite sheets can be installed as the magnetic shield 634. Mu-metal is a nickel-iron soft ferromagnetic alloy with high permeability. Mu-metal can be used for shielding sensitive electronic equipment against static or low-frequency magnetic fields. Soft ferrite materials, such as Manganese-zinc (MnZn, with the chemical formula MnaZnq-a)Fe2O4) and Nickel-zinc ferrite (NiZn, with the chemical formula NiaZn(i-a)Fe2C>4) can be used as magnetic shields. A combination of electrical and magnetic shields can be used by interleaving the sheets of electrical and magnetic shielding materials. The housing 630 can enclose the magnetic shield 634.

[0070] In some embodiments, the one or more NMR coils 110 can be disposed in the magnet assembly 605. The integrated circuit 500 can include the transmitter 515 configured to output an RF signal to the one or more NMR coils 110. The integrated circuit 500 can include the receiver 520 configured to receive an NMR signal from the one or more NMR coils 110.

[0071] In some embodiments, the system 600 can include one or more shimming coils. The one or more shimming coils can be configured to counter field inhomogeneity in the magnet assembly 605. The magnetic field can be adjusted to achieve improved field homogeneity. The magnetic field can be adjusted by applying electrical current into a set of coils to provide magnetic field corrections. These magnetic field shimming coils can produce magnetic fields with different spatial characteristics in order to counter the field inhomogeneity present in the magnet assembly 605.

[0072] A sensor assembly 635 can include the NMR sensor 100, the integrated circuit 500, the magnet assembly 605, the metallic shield 632, and / or the magnetic shield 634. The sensor assembly 635 can include an integrated (e.g., monolithic, single device / unit) sensor assembly. The sensor assembly 635 can include connections for fluid to enter and / or exit. For example, the connections can include the channel. The sensor assembly 635 can include electrical connections 640 that carry both the power supply and digital signals for operating154907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC the NMR sensor 100 and data collection. The NMR sensor 100 may have wireless connectivity to other sensors and / or to remote computers for configuration, measurement, and data management.

[0073] FIG. 7 illustrates a method 700 of characterizing fluids. In brief summary, the method 700 can include providing a magnet assembly (BLOCK 705). The method 700 can include receiving a fluid sample (BLOCK 710). The method 700 can include capturing magnetic debris (BLOCK 715). The method 700 can include passing the fluid sample through the magnet assembly (BLOCK 720). The method 700 can include executing an NMR pulse sequence (BLOCK 725). The method 700 can include acquiring an NMR signal (BLOCK 730).

[0074] The method 700 can include providing the magnet assembly (BLOCK 705). The magnet assembly can include the one or more first magnets. The one or more first magnets can be part of the NMR sensor. The NMR sensor can include the magnet assembly and the NMR coil.

[0075] The method 700 can include receiving the fluid sample (BLOCK 710). For example, the method 700 can include receiving, by the inlet, the fluid sample from the source. In some embodiments, the method 700 can include outputting the fluid sample to the source. For example, the method 700 can include outputting, by the outlet, the fluid sample from the source.

[0076] The method 700 can include capturing magnetic debris (BLOCK 715). For example, the method 700 can include capturing, by the magnetic debris trap, magnetic debris from the fluid sample. The magnetic debris trap can be positioned downstream of the inlet and upstream of the magnet assembly.

[0077] The method 700 can include passing the fluid sample through the magnet assembly (BLOCK 720). The fluid sample can flow through the magnet assembly, along a defined path (e.g., configured using tubing(s) or channel(s) constructed from non-magnetic material). The NMR sensor can be configured to measure one or more properties of the fluid sample as the fluid sample passes through the magnetic assembly. The magnetic debris can be captured by the magnetic debris trap prior to the sample passing through the magnet assembly.164907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0078] The method 700 can include executing the NMR pulse sequence (BLOCK 725). For example, the method 700 can include executing, by the integrated circuit, the NMR pulse sequence.

[0079] The method 700 can include acquiring the NMR signal (BLOCK 730). For example, the method 700 can include acquiring, by the integrated circuit, the NMR signal. The NMR signal can correspond to one or more characteristics of the fluid sample. The method 700 can include acquiring the NMR signal responsive to the NMR pulse sequence.

[0080] In some embodiments, the method 700 can include positioning the magnet assembly, the integrated circuit, and at least a portion of the magnetic debris trap in the housing. Alternatively, in some embodiments, the method 700 can include positioning the magnet assembly and the integrated circuit in the housing and positioning the magnetic debris trap exterior to the housing.

[0081] In some embodiments, the method 700 can include reducing interference from electric fields and magnetic fields. For example, the method 700 can include reducing, by the metallic shield, interference from electric fields and magnetic fields having a frequency in the range of 100 kHz and 300 GHz.

[0082] In some embodiments, the method 700 can include reducing interference from magnetic fields. For example, the method 700 can include the method 700 can include reducing, by the magnetic shield, interference from magnetic fields having the frequency in a range of 1 Hz and 100 kHz.

[0083] Embodiments of the subject matter and the operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. The subject matter described in this specification can be implemented as one or more computer programs, e.g., one or more circuits of computer program instructions, encoded on one or more computer storage media for execution by, or to control the operation of, data processing apparatus. Alternatively or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a174907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium may not be a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate components or media (e.g., multiple CDs, disks, or other storage devices).

[0084] The operations described in this specification can be performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources. The term “data processing apparatus” or “computing device” encompasses various apparatuses, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations of the foregoing. The apparatus can include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures.

[0085] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a circuit, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more circuits, subprograms, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.184907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC

[0086] Processors suitable for the execution of a computer program include, by way of example, microprocessors, and any one or more processors of a digital computer. A processor can receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer are a processor for performing actions in accordance with instructions and one or more memory devices for storing instructions and data. A computer can include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. A computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a personal digital assistant (PDA), a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few. Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0087] To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0088] The implementations described herein can be implemented in any of numerous ways including, for example, using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.

[0089] Also, a computer may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include printers or display screens for194907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC visual presentation of output and speakers or other sound-generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computer may receive input information through speech recognition or in other audible formats.

[0090] Such computers may be interconnected by one or more networks in any suitable form, including a local area network or a wide area network, such as an enterprise network, an intelligent network (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

[0091] A computer employed to implement at least a portion of the functionality described herein may comprise a memory, one or more processing units (also referred to herein simply as “processors”), one or more communication interfaces, one or more display units, and one or more user input devices. The memory may comprise any computer-readable media, and may store computer instructions (also referred to herein as “processor-executable instructions”) for implementing the various functionalities described herein. The processing unit(s) may be used to execute the instructions. The communication interface(s) may be coupled to a wired or wireless network, bus, or other communication means and may therefore allow the computer to transmit communications to or receive communications from other devices. The display unit(s) may be provided, for example, to allow a user to view various information in connection with execution of the instructions. The user input device(s) may be provided, for example, to allow the user to make manual adjustments, make selections, enter data or various other information, or interact in any of a variety of manners with the processor during execution of the instructions.

[0092] The various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

[0093] In this respect, various inventive concepts may be embodied as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., a computer204907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other non-transitory medium or tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the solution discussed above. The computer-readable medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present solution as discussed above.

[0094] The terms “program” or “software” are used herein to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of embodiments as discussed above. One or more computer programs that when executed perform methods of the present solution need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present solution.

[0095] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Program modules can include routines, programs, objects, components, data structures, or other components that perform particular tasks or implement particular abstract data types. The functionality of the program modules can be combined or distributed as desired in various embodiments.

[0096] Also, data structures may be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that convey relationship between the fields. However, any suitable mechanism may be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements.

[0097] Any references to implementations or elements or acts of the systems and methods herein referred to in the singular can include implementations including a plurality of these elements, and any references in plural to any implementation or element or act herein can include implementations including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their214907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC components, acts, or elements to single or plural configurations. References to any act or element being based on any information, act or element may include implementations where the act or element is based at least in part on any information, act, or element.

[0098] Any implementation disclosed herein may be combined with any other implementation, and references to “an implementation,” “some implementations,” “an alternate implementation,” “various implementations,” “one implementation” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the implementation may be included in at least one implementation. Such terms as used herein are not necessarily all referring to the same implementation. Any implementation may be combined with any other implementation, inclusively or exclusively, in any manner consistent with the aspects and implementations disclosed herein.

[0099] References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms.References to at least one of a conjunctive list of terms may be construed as an inclusive OR to indicate any of a single, more than one, and all of the described terms. For example, a reference to “at least one of ‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and ‘B’. Elements other than ‘A’ and ‘B’ can also be included.

[0100] The systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof. The foregoing implementations are illustrative rather than limiting of the described systems and methods.

[0101] Where technical features in the drawings, detailed description or any claim are followed by reference signs, the reference signs have been included to increase the intelligibility of the drawings, detailed description, and claims. Accordingly, neither the reference signs nor their absence have any limiting effect on the scope of any claim elements.

[0102] The systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof. The foregoing implementations are illustrative rather than limiting of the described systems and methods. Scope of the systems and methods described herein is thus indicated by the appended claims, rather than the foregoing description, and changes that come within the meaning and range of equivalency of the claims are embraced therein.224907-7018-4849.2

Claims

1. Atty. Dkt. 098930-0432HU 10124 PC WHAT IS CLAIMED IS:

1. A system, comprising:a magnet assembly comprising one or more first magnets;an inlet configured to receive a fluid sample from a source, the fluid sample configured to pass through the magnet assembly;a magnetic debris trap positioned downstream of the inlet and upstream of the magnet assembly, the magnetic debris trap comprising a second magnet configured to capture magnetic debris from the fluid sample; andan integrated circuit configured to execute a nuclear magnetic resonance (NMR) pulse sequence and acquire an NMR signal corresponding to one or more characteristics of the fluid sample.

2. The system of claim 1, comprising:an outlet configured to output the fluid sample to the source.

3. The system of claim 1, wherein the magnet assembly, the integrated circuit, and at least a portion of the magnetic debris trap are positioned in a housing.

4. The system of claim 1, wherein:the magnet assembly and the integrated circuit are positioned in a housing; and the magnetic debris trap is positioned exterior to the housing.

5. The system of claim 1, wherein the magnetic debris trap comprises a plug.

6. The system of claim 1, comprising:a channel comprising a material inert to the fluid sample,wherein the channel is configured to couple with the inlet and receive the fluid sample.

7. The system of claim 1, comprising:a pump configured to convey the fluid sample from the source to the magnet assembly.234907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC 8. The system of claim 1, comprising:a metallic shield configured to reduce interference from electric fields and magnetic fields having a frequency in a range of 100 kHz and 300 GHz.

9. The system of claim 1, comprising:a magnetic shield configured to reduce interference from magnetic fields having a frequency in a range of 1 Hz and 100 kHz.

10. The system of claim 1, comprising:an NMR coil disposed in the magnet assembly;wherein the integrated circuit comprises:a transmitter configured to output an RF signal to the NMR coil; and a receiver configured to receive an NMR signal from the NMR coil.

11. The system of claim 1, wherein:the magnet assembly and the integrated circuit are positioned in a housing; and the housing is coupled with a vibration-isolation device.

12. The system of claim 1, comprising:thermal insulation positioned around the magnet assembly;wherein the integrated circuit comprises a controller configured to:determine a Larmor frequency of the system; andadjust a frequency of the system to the Larmor frequency.

13. The system of claim 1, comprising:one or more shimming coils configured to counter field inhomogeneity in the magnet assembly.

14. The system of claim 1, wherein the integrated circuit comprises a controller configured to control a valve configured to control flow of the fluid sample from the source to the magnet assembly.

15. A method, comprising:providing a magnet assembly comprising one or more first magnets;244907-7018-4849.2Atty. Dkt. 098930-0432HU 10124 PC receiving, by an inlet, a fluid sample from a source;capturing, by a magnetic debris trap positioned downstream of the inlet and upstream of the magnet assembly, magnetic debris from the fluid sample;passing the fluid sample through the magnet assembly;executing, by an integrated circuit, an NMR pulse sequence; andacquiring, by the integrated circuit, an NMR signal corresponding to one or more characteristics of the fluid sample and responsive to executing the NMR pulse sequence.

16. The method of claim 15, comprising:outputting, by an outlet, the fluid sample to the source.

17. The method of claim 15, comprising:positioning the magnet assembly, the integrated circuit, and at least a portion of the magnetic debris trap in a housing.

18. The method of claim 15, comprising:positioning the magnet assembly and the integrated circuit in a housing; and positioning the magnetic debris trap exterior to the housing.

19. The method of claim 15, comprising:reducing, by a metallic shield, interference from electric fields and magnetic fields having a frequency in a range of 100 kHz and 300 GHz.

20. The method of claim 15, comprising:reducing, by a magnetic shield, interference from magnetic fields having a frequency in a range of 1 Hz and 100 kHz.254907-7018-4849.2

Images