System and method for investigating a cell

Abstract

A system and method for investigating a cell are provided. In some aspects, the system includes a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base, and a magnetic measurement apparatus operable to perform a magnetic field measurement on a sample comprising a cell localized in the sample receptacle. The magnetic measurement apparatus includes a magnetic probe having a resonant frequency, and an actuator system, connected to the magnetic probe, that drives the magnetic probe at a driving frequency or at the resonant frequency to sense a magnetic field in or about the sample. The system also includes an electrical measurement apparatus operable to perform an electrical measurement on the sample.

Description

Atorney Docket No. 065472-000982W02TSYSTEM AND METHOD FOR INVESTIGATING A CELLCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of, and priority to, U.S. Provisional Patent Application No. 63 / 716,155 filed on November 4, 2024, and U.S. Provisional Patent Application No. 63 / 716,139 filed on November 4, 2024, each of which is hereby incorporated by reference herein in its entirety.BACKGROUND

[0002] Understanding biochemical and electrical signaling processes that underlie dynamic neural activity in a mammalian brain can have important impacts on research and therapeutic endeavors. For instance, understanding magnetic field dynamics can be useful in revealing neural coding and brain function. Also, decoding activity-dependent magnetic field dynamics in cellular and subcellular structures is vital for the development of next-generation non- invasive neuromodulatory technology.

[0003] Thus far, however, causes and consequences of magnetic fields generated by activity of individual neurons remain elusive. In part, this may be because conventional techniques used to perturb and measure magnetic fields in a brain are limited. For example, magnetoencephalography, and other techniques, can measure only macroscopic magnetic fields, thereby reflecting aggregate activity of many neurons across large regions of the brain.

[0004] Therefore, there is a need for an improved technologies for investigating cells.SUMMARY

[0005] In one aspects of the present disclosure, a system for investigating a cell is provided.The system includes a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base, and a magnetic measurement apparatus operable to perform a magnetic field measurement on a sample comprising a cell localized in the sample receptacle. The magnetic measurement apparatus includes a magnetic probe having a resonant frequency, and an actuator system, connected to the magnetic probe, that drives the magnetic probe at a driving frequency or at the resonant frequency to sense a magnetic field in or about the sample. The system also includes an electrical measurement apparatus operable to perform an electrical measurement on the sample.- 1 -4908-8500-3894Atomey Docket No. 065472-000982W02T

[0006] In another aspect of the present disclosure, a method for investigating a cell is provided. The method includes providing a measurement system that comprises a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base. The method also includes controlling a magnetic measurement apparatus of the measurement system to perform a magnetic field measurement on a sample using a magnetic probe, wherein the sample comprises a cell localized in the sample receptacle, and controlling an electrical measurement apparatus of the system to perform an electrical measurement on the sample. The method further includes generating a report indicative of the magnetic field measurement and electrical measurement on the sample.

[0007] The foregoing summary is not intended to represent each embodiment or every aspect of the present disclosure. Rather, the summary merely provides an example of some of the novel aspects and features set forth herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of representative embodiments and modes for carrying out the present approach, when taken in connection with the accompanying drawings and the appended claims.BRIEF DESCRIPTION OF DRAWINGS

[0008] The present disclosure is described with reference to the attached drawings, where like reference numerals are used throughout the drawings to designate similar or equivalent elements. The drawings are not drawn to scale and are provided merely for illustration. Several aspects of the disclosure are described below with reference to example applications for illustration.

[0009] FIG. 1 is schematic diagram of an example system, according to aspects of the present disclosure.

[0010] FIG. 2A is an illustration of an example sample substrate, according to aspects of the present disclosure.

[0011] FIG. 2B is a side view along line A- A’ in the example sample substrate of FIG 2A showing one embodiment, according to aspects of the present disclosure.

[0012] FIG. 2C is a side view along line A- A’ in the example sample substrate of FIG 2A showing another embodiment, according to aspects of the present disclosure.

[0013] FIG. 2D is a side view along line A- A’ in the example sample substrate of FIG 2A showing yet another embodiment, according to aspects of the present disclosure.

[0014] FIG. 2E is a side view along line A- A’ in the example sample substrate of FIG 2A- 2 -4908-8500-3894Atorney Docket No. 065472-000982W02T showing yet another embodiment, according to aspects of the present disclosure.

[0015] FIG. 3A is an illustration showing example sample suspended in a cell suspension for measurement, according to aspects of the present disclosure.

[0016] FIG. 3B is an illustration showing measurement of the sample in FIG. 3 A, according to aspects of the present disclosure.

[0017] FIG. 4 is an illustration of another example system, according to aspects of the present disclosure.

[0018] FIG. 5A is an illustration of an example magnetic probe, according to aspects of the present disclosure.

[0019] FIG. 5B is a graphical illustration showing resonant properties and measurement using the example magnetic probe of FIG. 5B, according to aspects of the present disclosure.

[0020] FIG. 6 is a flowchart setting forth steps of a process, according to aspects of the present disclosure.

[0021] Advantages of the present disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.DETAILED DESCRIPTION

[0022] Understanding cellular and synaptic activity can be critical for determining neural circuit dynamics that support cognitive function. For instance, it is believed that sources of activity dependent magnetic fields at the sub-cellular level result from transmembrane currents through ion channels, in addition to intracellular axial currents that flow along neuronal processes. Whether these are sole contributors or significant sources of underlying magnetic field generation remains unclear. Generally, electro-diffusion phenomena generating magnetic fields within the micro- and nanodomains of synapses and cells have been largely unexplored. Notably, there are circumstances where a magnetic field measurement can be a more faithful reporter of neural dynamics relative to an electric measurement. Indeed, electrically silent magnetic fields can arise in a variety of scenarios where the cyto-architectonic geometry of the neuropil is favorable, such as at bifurcation points of complex dendritic tree structures. Therefore, a significant knowledge gap remains regarding magnitude, dynamics, and functional impact of activity-dependent magnetic fields at the cellular and subcellular levels.

[0023] Previous measurements using conventional techniques have indicated that neuronal action potentials can generate detectable magnetic fields. Yet despite such indication, conventional approaches make magnetic field measurements relatively far from cells that generate such fields, potentially leading to inaccurate perception of contribution to- 3 -4908-8500-3894Atorney Docket No. 065472-000982W02T physiological function. Hence, current tools fall short of measurement and perturbation of magnetic fields in live biological systems at the scale of individual neurons.

[0024] Further, conventional conceptual frameworks used to describe electro-diffusion phenomena in the brain make critical assumptions that may not be valid at the microscale of individual neurons and the nanoscale of subcellular compartments. For example, one current theoretical framework used to model and interpret physiological data assumes that no magnetic fields are present and relies on a principle of electroneutrality. Electroneutrality assumes that in a bulk electrolyte solution of freely moving ions, any transient local accumulation of electric charge and field strength is rapidly compensated by electro-diffusion of counterions. Thus, at relatively long length scales and time epochs, aqueous electrolyte in brain tissue (i.e., cerebrospinal fluid) can approximated to be electrically neutral.

[0025] By contrast, ions in solution have low magnetic susceptibility, which allows magnetic fields to propagate relatively unimpeded. Importantly, there are several physiological scenarios where electroneutrality may not apply. For example, electroneutrality can be violated at micrometer to nanometer length scales, such as an interface between a neuronal cell membrane and intracellular polyelectrolytes in aqueous electrolyte solution. At such spatial scales, solvated ions organize into capacitive layers along the membrane or polyelectrolyte interface giving rise to a junction potential. During neuronal action potentials, transmembrane currents mediated by ion channels can drive about 100 millivolt (mV) fluctuations in voltage over 1-2 milliseconds (ms). Such voltage dynamics can cause rapid fluctuations of ionic species, giving rise to micro- or nanodomain electrical currents mediated by ionic flux. Ionic fluctuations can occur over nanometers, and can produce magnetic fields with steep gradients that can interact over distances far longer than those of electric fields (which are shielded), the physiological significance of which remains to be determined. And so, juxta-membrane nanodomain and subcellular architectonics of neurons represent various scenarios in which conventional assumptions of electroneutrality may be violated. Such assumptions produce systematic knowledge gaps in physiological processes at the micro- and nano-scale that were previously considered to be understood.

[0026] It is therefore recognized herein that new technologies are needed for investigating one or more cell, and / or cellular tissue including, for instance, technologies that can measure activity-dependent magnetic fields with sufficient sensitivity and precision to achieve cellular resolution. As appreciated from description herein, the present disclosure provides a number of benefits and improvements over conventional fields of technology, such as conventional technologies for investigating cells and cellular tissue.- 4 -4908-8500-3894Atorney Docket No. 065472-000982W02T

[0027] Referring particularly to FIG. 1, an example of a system 100, according to aspects of the present disclosure, is illustrated. In general, the measurement system 100 may include a sample assembly 102, an electrical measurement apparatus 104, and a magnetic measurement apparatus 106. In some embodiments, the measurement system 100 may also include a controller 108.

[0028] The sample assembly 102 may include a variety of components and hardware, capable of holding, supporting, securing, positioning, and / or orienting one or more sample (e.g., neural cell, neural tissue, cardiac cell, cardiac tissue, muscle cell, muscle tissue, and so forth). In some embodiments, the sample assembly 102 includes a sample substrate. The sample substrate may have any shape, dimension, and may be made using various materials. In some applications, the sample substrate may be used to culture various cells, cellular tissue, and so forth. To this end, sample substrate may be shaped, dimensioned, and made using material(s) suitable for such culture. In one non-limiting example, the sample substrate is a cell culture dish with a diameter between approximately 20 mm and approximately 50 mm, although diameter values may be possible. In another non-limiting example, the sample substrate is a slide.

[0029] In some embodiments, the sample substrate includes a base with a sample receptacle formed in the base that is shaped and dimensioned to hold the sample(s) therein. In particular, the sample receptacle may be formed by an opening in the base and a membrane that spans the opening in the base. In some embodiments, the membrane may include, for example, a silicon nitride membrane with a thickness between approximately 10 nanometers (nm and approximately 40 nm, although thickness values greater or less than 25 nm may be possible. As appreciated from description herein, a sample substrate, according to aspects of the present disclosure, allows for a magnetic probe to closely approach a sample on the sample substrate (e.g., from below the sample substrate) to sense magnetic fields in or about the sample, as well as induce magnetic fields in or about the sample.

[0030] In some embodiments, the sample assembly 102 may include a movable stage that may be configured or operated to move in one or more directions to position and / or orient the sample substrate, and sample(s) thereon. For instance, the movable stage may include, or be engaged with, various components and / or hardware, such as one or more gear, actuator, motor, and so forth. The movable stage may move, for example, on one or more rail, bridge, track, and so forth.

[0031] The electrical measurement apparatus 104 may include a variety of components and hardware configured or operated to acquire various electrical measurements from one or more- 5 -4908-8500-3894Atorney Docket No. 065472-000982W02T sample held in the sample assembly 102. For example, the electrical measurement apparatus 104 may include one or more amplifier, resistor, capacitor, inductor, digitizer, voltmeter, current meter, and so forth. In some embodiments, the electrical measurement apparatus 104 may be configured or operated to perform a patch-clamp measurement. To this end, the electrical measurement apparatus 104 may include a patch-clamp pipette including a conducting solution (e.g., an electrolyte solution), an electrode electrically immersed in or connected to the conducting solution, an operational amplifier connected to the conducting solution via the electrode, one or more resistor (e.g., a feedback resistor) connected to the conducting solution, and a measurement device connected to the resistor(s) and operational amplifier. In particular, the patch-clamp pipette may be configured or operated to engage one or more sample in the sample assembly 102 and provide various electrical measurements.

[0032] The magnetic measurement apparatus 106 may include a variety of components and hardware configured or operated to perform various magnetic field measurements from one or more sample held or localized in the sample assembly 102. In some embodiments, the magnetic measurement apparatus 106 may include a magnetic force microscopy (MFM) system or MFM module that may acquire magnetic signals using a magnetic probe. The magnetic probe may be a contact magnetic probe, a non-contact magnetic probe, a tapping magnetic probe, and so forth. In some embodiments, the magnetic probe, or portions thereof, is magnetic by virtue of materials or alloys used therein (e.g., Fe, Co, Ni, Nd, NdFeB, CoCr, and so forth). In other embodiments, the magnetic probe, or portions thereof, may be functionalized to be sensitive to magnetic fields. In one non-limiting example, the magnetic probe is a tuning fork that includes a first, magnetic prong (e.g., by way of a magnetic material, magnetic coating, magnetic tip, magnetic wire, and so forth), and a second, non-magnetic prong. To establish a single resonant frequency for the tuning fork, the second, non-magnetic probe may be modified (e.g., weighted to match or exceed a weight the first, magnetic prong of the tuning fork).

[0033] To obtain one or more magnetic measurement from the sample(s) in the sample assembly 102, the magnetic probe may be driven at a driving frequency between approximately 30 kiloHertz (kHz) and approximately 300 kHz, which may correspond to a resonant frequency of the magnetic probe. For instance, the magnetic probe may be driven using an actuator system, or component therein, connected to the magnetic probe. In some embodiments, the actuator system may include a piezo-actuator.

[0034] In some implementations, signals acquired by the MFM system or MFM module may correspond to changes in amplitude / frequency / phase of oscillation of the magnetic probe driven at the resonance frequency or the driving frequency. Specifically,- 6 -4908-8500-3894Atorney Docket No. 065472-000982W02T amplitude / frequency / phase changes may occur due to a magnetic force on the magnetic probe from magnetic field in or about the sample(s). To this end, the MFM system or MFM module may include or communicate with components and hardware capable of detecting and / or quantifying such amplitude / frequency / phase changes, for instance, to generate various signals corresponding to magnetic field in or about the sample(s) (i.e., magnetic signals). The generated signal(s) may then be analyzed to generate a representation indicating various the magnetic field values and / or spatial distribution of magnetic field values in or about the sample(s) sensed using the magnetic probe. In some implementations, the representation may be in any form including tabular, graphical, images, and so forth. re

[0035] In some embodiments, the measurement system 100 may optionally include a controller 108. By way of example, the controller 108 may include a computing device (e.g., laptop, computer, and so forth), a personal device (e.g., smartphone, tablet, and so forth), as well as any other system, device, or apparatus suitable for carrying out steps, as described herein. The controller 108 may be operable, for instance, by way of programming and / or hardwired instructions therein, to control functionality or direct operation of the sample assembly 102, electrical measurement apparatus 104, magnetic measurement apparatus 106, or a combination thereof. For instance, the controller 108 may control acquisition (e.g., acquisition timing, sampling rate, triggering, and so forth), processing, and / or analysis of various signals (e.g., electrical signals, magnetic signals, and so forth). The controller 108 may also control operation various components of the sample assembly 102, electrical measurement apparatus 104, and / or magnetic measurement apparatus 106, or a combination thereof. For instance, the controller 108 may control a position and / or orientation of a sample holder of the sample assembly 102 (e.g., via motor, gear, actuator, and so forth). As such, the controller 108 may generate and transmit various control signals (e.g., in the form of voltage signals, current signals, optical signals, and so forth) via wired and / or wireless communication.

[0036] In some implementations, the controller 108 may also control operation of an MFM system or MFM module, or various components therein. For instance, the controller 108 may direct an actuator (e.g., a piezo-actuator) or actuator system to control a driving frequency of a magnetic probe, a vertical approach or vertical position of the magnetic probe relative to the sample(s), a lateral scan of the magnetic probe, and so forth. In some implementations, the controller 108 may receive various magnetic signals generated using the magnetic probe, and process and / or assemble the magnetic signals in a representation. For example, the representation may be in the form of a graph, table, image, listing, graphics, and so, forth.

[0037] In some implementations, the magnetic probe of the MFM system or MFM probe- 7 -4908-8500-3894Atomey Docket No. 065472-000982W02T may be used to perturb a magnetic field in or about the sample(s). For instance, an applied magnetic field may be provided to the sample(s) by controlling the magnetic probe. In particular, the controller 108 may control driving frequency, vertical approach, vertical position, lateral scan parameters (e.g., scan range, scan speed, and so forth), and so forth.

[0038] In some implementations, the controller 108 may control application of the magnetic field in or about the sample(s), for instance, by controlling a driving frequency of the magnetic probe, a vertical approach of the magnetic probe, a position of the magnetic probe relative to the sample(s), a lateral scan of the magnetic probe, and so forth.

[0039] To control functionality or operation, the controller 108 may include or communicate with various control, acquisition, and / or processing hardware. For example, the controller 108 may include and / or communicate with one or more data acquisition card, board, signal conditioner, module, relay, sensor, detector, camera and so forth. In some embodiments, the controller 108 may be operable to coordinate or synchronize acquisition of signals, for example, such as electric signals and magnetic signals. For instance, the controller 108 may utilize various timing control mechanisms, such as triggering, and so forth. For example, the controller 108 may send a trigger signal to both the magnetic measurement apparatus and the electrical measurement apparatus to initiate synchronized measurement, thereby producing correlated electric signals and magnetic signals.

[0040] In some embodiments, the measurement system 100 may optionally include an optical system or module. For example, the optical system or module may be used to image the sample(s) in the sample assembly 102. To this end, the optical system or module may include a variety of optical components and hardware, such as one or more light source, polarizer, filter, splitter, objective, mirror, collimator, grating, prism, diffuser, retarder, lens, wheel, polarimeter, detector, camera, and so forth. In some embodiments, the controller 108 may control a position and / or orientation of the optical system or module, and / or various components therein. In particular, the controller 108 may communicate with hardware control (e.g., motor, gear, actuator, and so forth) to position and / or orient various optical elements or components (e.g., source, mirror, objective, condenser, filter, camera, and so forth) between different configurations. For example, the controller 108 may control toggling of a condenser in and out of a transmitted light path provided by a light source.

[0041] In some embodiments, the measurement system 100, or one or more component therein, may be contained in a housing. The housing may include various materials. For instance, in some embodiments, the housing may include a magnetic shielding made, for instance, using a ferromagnetic material (e.g., mu-metal) that passively reduce or eliminates- 8 -4908-8500-3894Atorney Docket No. 065472-000982W02T electromagnetic noise. In some embodiments, the housing may include a frame or cage containing one or more coil (e.g., Helmholtz coil), which may actively reduce or eliminate electromagnetic noise. In some embodiments, the measurement system 100, or one or more component therein, may be installed on a vibration isolation table or air table frame, which may reduce or eliminate mechanical vibration noise.

[0042] The measurement system 100 described above may be used for a variety of applications, including investigating one or more cell, cellular tissue, as well as properties or functions thereof. For instance, the measurement system 100 may be used to measure activitydependent magnetic fields in a neuronal cell, as well as induce or apply magnetic field therein or thereabout, in a controlled way.

[0043] Turning now to FIGs. 2A-2E, an example of a sample substrate 210, in accordance with aspects of the present disclosure, is illustrated. Referring particularly to FIG. 2A, the sample substrate 210 may include a base 220, and a wall 240 extending vertically from the base 220. The wall 240 may help contain culture media, or

[0044] The base 220 may be defined by a first, top surface 222 and a second, bottom surface 224, extending to a diameter between approximately 20 mm and approximately 50 mm, although the base 220 may have various dimensions and shapes.

[0045] The sample substrate 210 may include a sample receptacle 260 formed in the base 220, where the sample receptacle 260 may receive and / or localize one or more sample. As shown in FIG. 2A, in some embodiments, the sample receptacle 260 is formed by an opening 262 in the base 220 and a membrane 264 that spans the opening 262. In particular, the opening 262 and membrane 264 form a cavity defined at least by a width wl of the opening 262 and a depth dl, as measured from top surface 222 of the base 220. Dimensions of the cavity may vary, for instance, selected to provide sufficient space for receiving, localizing, and / or handling the sample(s).

[0046] In some embodiments, the membrane 264 may have a thickness t between approximately 10 nm and approximately 40 nanometers, although the membrane 264 may have various dimensions and shapes. The membrane 264 may also have various properties. For instance, in some embodiments, the membrane 264 is non-magnetic. A membrane 264 that is non-magnetic can help prevent a disruption of magnetic fields in or about the sample(s). In some embodiments, the membrane 264 is insulating. A membrane 264 that is insulating can help prevent a disruption of electrical signals in or about the sample(s). In some embodiments, the membrane 264 is, in whole or in part, transparent to light, such as light in the visible spectrum, light in the infrared spectrum, and so forth. A membrane 264 that is transparent may- 9 -4908-8500-3894Atomey Docket No. 065472-000982W02T allow light to travel through the membrane 264, thereby facilitating visibility or imaging of the sample(s) disposed on the membrane 264 through the membrane 264. By way of example, the membrane 264 may be silicon-nitride membrane.

[0047] The way in which the membrane 264 is incorporated and / or secured to the base 220 may vary, as illustrated in FIGs. 2B-2E. For instance, in some embodiments, the base 220 may include a straight edge 226 forming a straight step in the base 220 that receives the membrane 264, as shown in FIG. 2B. Alternatively, in some embodiments, the base 220 may include a tapered edge or beveled edge 228 forming a tapered step or beveled step in the base 220 that receives the membrane 264, as shown in FIG. 2C. The beveled edge 228 allows the magnetic probe to get closer to the sample(s) in the sample receptacle 260 (e.g., within a distance of tens of nanometers) without risk of encountering the base 220. To note, while FIGs. 2A and 2B show embodiments where the thickness t of the membrane 264 is less than the thickness T of the base 220, in other embodiments, the thickness t of the membrane 264 may be equal to or more than the thickness T of the base 220. Hence, the membrane 264 may be flush with, or extend vertically beyond, the bottom surface 224 of the base 220.

[0048] The membrane 264 may be secured or held in place using various methods. For instance, in the embodiment shown in FIG. 2B, the membrane 264 may be held in place mechanically (e.g., via press-fit, fastener, washer, annulus, O-ring and so forth). In the embodiment shown in FIG. 2C, the membrane 264 may also be held in place mechanically (e.g., via fastener, washer, annulus, O-ring, and so forth), as well as chemically (e.g., via adhesive, surface tension, and so forth).

[0049] In some embodiments, the base 220 of the sample substrate 210 may include a slot 230 that extends a depth d2 in the base 220. In some embodiments, the slot 230 may be formed directly in the base 220, as shown in FIG. 2D. Alternatively, the slot 230 may be formed by virtue of assembling a first base portion 220’ to a second based portion 220”, where the first base portion 220’ and second base portion 220” form the base 220. For example, first base portion 220’ and second base portion 220” may be pressed, glued, epoxied, fastened, and so forth, to form the base 220.

[0050] While FIGs. 2A-2E show the sample substrate 210 in the form of a dish, variations of the sample substrate 210 may be possible. For instance, the base 220 of the sample substrate 210 need not be circular, and may have any shape (e.g., oval, square, rectangle, and so forth) and dimension. Similarly, the sample receptacle 260 need not be circular, and may have any shape (e.g., oval, square, rectangle, and so forth) and dimension. In some embodiments, the sample substrate 210 may not have a wall 240, as shown in FIG. 2 A. Also, in some- 10 -4908-8500-3894Atorney Docket No. 065472-000982W02T embodiments, the sample substrate 210 may have more than one sample receptacle 260. Such sample receptacle(s) 260 may be located at any position along the base 220, as well as arranged in any configuration or pattern on the base 220.

[0051] As illustrated in FIGs. 3 A-3B, in some applications, a sample in the form of a cell suspension may be dispensed on a sample substrate 310 of a sample assembly 302, and more particularly, on a sample receptacle 360 of the sample substrate 310. For example, the cell suspension may include a liquid medium (e.g., culture medium) and one or more cell (e.g., a neuron) and / or cellular tissue immersed in the liquid medium. The cell suspension may adhere to the sample receptacle 360, allowing the cell(s) and / or cellular tissue therein to be localized (FIG. 3 A). In some applications, neurons or other cells or tissue in the cell suspension may be cultured in the sample substrate 310 and / or sample receptacle 360.

[0052] As shown in FIG. 3B, one or more localized cell may be measured, in accordance with aspects of the present disclosure. For instance, an electrical measurement apparatus 304 may utilize a pipette 370 that may secure to a cell, and perform a patch-clamp measurement technique. Furthermore, a magnetic measurement apparatus 306 may perform magnetic measurements using a MFM system or MFM module utilizing a magnetic probe 380 operated by an actuator system 390. As shown in FIG. 3B, the magnetic measurement apparatus 306 may be arranged to sense magnetic field from below the sample(s). In particular, the magnetic measurement apparatus 306 may be arranged below the membrane 364 such that the magnetic probe 380 may sense magnetic field through the membrane 364. As appreciated from FIG. 3, arrangement of the electrical measurement apparatus 304 and magnetic measurement apparatus 306 allows for correlated (e.g., substantially simultaneous) electric and magnetic field measurements.

[0053] As described, in some embodiments, the magnetic probe 380 may include a tuning fork that includes a first, magnetic prong (e.g., by way of a magnetic material, magnetic coating, magnetic tip, magnetic wire, and so forth), and a second, non- magnetic prong. In some embodiments, the actuator system 390 includes a piezo-actuator. In some implementations, electrical measurements and magnetic measurements may be correlated, for example, using a triggering technique applied by a controller, as described.

[0054] In general, MFM is a form of scanning probe microscopy in which a scanning probe is systematically scanned around a sample of interest to measure magnetic properties. Analogous to an acoustic probe, which resonates at a particular frequency, a scanning probe also resonates at an intrinsic or resonant frequency. In an MFM system, the scanning probe may be functionalized with a magnetic tip (i.e., to produce a magnetic probe), which can enable- 11 -4908-8500-3894Atomey Docket No. 065472-000982W02T sensitive detection of magnetic field. As the scanning probe is scanned about the sample, the scanning probe may be subjected to a magnetic field in or about the sample. Deviations from the intrinsic or resonant frequency of the scanning probe may then be detected. Such deviations may be analyzed to determine a magnetic field distribution in the sample and / or magnetic properties of the sample. In particular, MFM can be sensitive to magnetic field gradients. And so, even if a magnetic field generated by a sample is weak, if a gradient of the magnetic field is strong (i.e., if magnetic field magnitude varies significantly over a short distance), the MFM system or MFM module may detect and use such gradient signals to characterize the sample.

[0055] In some embodiments, the sample assembly 302 may be capable of a 3-axis fine scale translation to position a magnetic probe under a cell being recorded by electrical measurement apparatus 304 performing patch-clamp electrophysiology or patch-clamp measurement technique (FIG. 3B). A piezo-actuator of the actuator system 390 may be used to progressively step the magnetic probe in close proximity to the sample. In some embodiments, the actuator system 390 and / or the MFM system / module may include, or be integrated into, a specialized mounting apparatus that can mechanically stabilize the magnetic probe, and may also support circuitry and hardware for high-sensitivity measurements. As described, in some implementations, both electrical (e.g., electrophysiological) and magnetic (e.g., MFM) measurements may be acquired simultaneously, for instance, during neuronal activity. Such correlated measurements may provide important information regarding cell function and other properties.

[0056] Referring to FIG. 4, an example of a system 400, in accordance with aspects of the present disclosure, is illustrated. As shown, the system 400 may be a modular measurement system that includes, among other elements, components, and modules, an MFM module 450 configured or operated to acquire magnetic field measurements from one or more sample, as described. As shown in FIG. 4, the MFM module 450 may be mounted on a movable or sliding bridge 452 next to the condenser 454, which can be toggled in-and-out of a transmitted light path 456 provided by a light source of an optical module or optical system.

[0057] In some modes of operation, the optical module / system, and / or various components therein, may be positioned (above or below the sample) to allow for visualization of a sample (e.g., a cell) on a sample substrate, for example, during application of a patch-clamping technique. In other modes of operation, the optical module / system may be shifted out of the transmitted light path 456 to allow the MFM module 450 to be positioned under the sample (e.g., cell). As illustrated in FIG. 4, the MFM module may be integrated into the system 400, and utilized in coordination with an electrical measurement system or module (e.g., a cellular- 12 -4908-8500-3894Atorney Docket No. 065472-000982W02T electrophysiology system). In some embodiments, the system 400 may be constructed using modular platforms, such as modular microscopy platforms available from Thorlabs, Inc. (Newton, New Jersey).

[0058] In some embodiments, the MFM module of the system 400 includes a magnetic probe, according to aspects of the present disclosure. By way of example, FIG. 5A illustrates an example magnetic probe 580, and more particularly, a tuning fork (TF), in accordance with aspects of the present disclosure. As shown, the TF may include a first prong 582’ and a second prong 582”. In some embodiments, the first prong 582’ may be a magnetic or magnetized prong, while the second prong 582” may be a non-magnetic prong. For instance, as shown in FIG. 5 A, the TF may be transformed into a magnetized TF by attaching a magnetic wire 584 (e.g., a 10-micron diameter Ni wire) to the first prong 582’, for example, using an adhesive (e.g., glue, epoxy, and so forth). Attaching the magnetic wire 584 to the first prong 582’, however, can result in the magnetized TF to exhibit two resonance frequency peaks, while a bare TF exhibits a single resonant peak, as illustrated in panel (a) of FIG. 5B. To (re)establish a single resonant frequency for the magnetized TF, the second, non-magnetic prong may be modified or (re)balanced (e.g., weighted to match or exceed a weight of the first prong 582’ with the magnetic wired 584 attached thereto).

[0059] In some implementations, a TF, magnetized as described, may be tested and / or calibrated. For instance, a magnetized TF may be tested using a magnetic standard that can provide a reference magnetic field value or a reference spatial distribution of magnetic field. Using a measurement system in accordance with the present disclosure, the magnetized TF may be used to detect a static magnetic field produced by the magnetic standard. For instance, in some implementations, current may be passed through a wire of known diameter, generating a reference magnetic field value, according to the following: B=n°I / 27r:r, where B is the magnetic field, ° is the permittivity constant (for free space), I is the magnitude of the current flowing through the wire, and r is the distance to the wire. In other implementations, a magnetized or magnetic needle of having a known magnetic field or spatial distribution of magnetic field may be used. A piezo-actuator, for instance, may be used to step the magnetized TF progressively (e.g., in sub-micron steps) the magnetic standard to one or more predetermined distance from the sample(s) to calibrate the magnetized TF.

[0060] By way of example, panel (b) in FIG. 5B illustrates magnetic field calibration measurement of a magnetized TF through a vertical approach toward a magnetic needle. As seen in FIG. 5B, the magnetic signal observed is an exponential signal that increases as the- 13 -4908-8500-3894Atomey Docket No. 065472-000982W02T magnetic needle is approached vertically. In some implementations, a lateral scan of the magnetic standard may also be performed. For example, as shown in panel (c) of FIG. 5B, performing a lateral scan about the magnetic needle shows a prominent signal when the TF is aligned with the magnetic needle, thereby demonstrating excellent sensitivity to the magnetic field and magnetic field gradients of the magnetic needle. Such measurement may then be compared to a reference magnetic field value and / or spatial distribution of magnetic field to provide calibration.

[0061] Following calibration, one investigation may proceed in the following manner using a measurement system, as described herein. First, with a condenser positioned in the transmitted light path, a patch-clamp electrophysiological recording may be obtained from a cell cultured in the silicon-nitride cavity. Subsequently, the condenser is toggled out of the light path and the MFM module is positioned directly underneath the recorded cell. The piezoactuator may be used to step the TF progressively closer to the bottom surface of the siliconnitride membrane (e.g., within a predetermined distance from the bottom surface of the membrane). With the TF in position, current may be injected into the cell (e.g., ramped current) to drive action potentials aligned to magnetic field measurements obtained using MFM.

[0062] Turning to FIG. 6, a flowchart setting forth steps of a process 600, according to aspects of the present disclosure, is illustrated. Steps of the process 600 may be carried out using any combination of suitable systems, such as systems described in the present disclosure. In some embodiments, steps of the process 600 may be implemented as instructions stored in non-transitory computer-readable media, as a program, firmware or software, and executed by a general-purpose, programmed or programmable computer, processor or other computing device. In other embodiments, steps of the process 600 may be hardwired in an applicationspecific computer, processor, dedicated system, or module. Although the process 600 is illustrated and described as a sequence of steps, it is contemplated that the steps may be performed in any order or combination, need not include all illustrated steps, and may include additional steps.

[0063] The process 600 may begin at process block 602 with providing a measurement system for investigating one or more cell and / or one or more cellular tissue. As described with reference to FIGs. 1-5B, such measurement system may include various features suitable for carrying out electrical and / or magnetic field measurement, in accordance with aspects of the present disclosure. For instance, the measurement system provided at process block 602 may include a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the- 14 -4908-8500-3894Atorney Docket No. 065472-000982W02T base. As described, the sample receptacle may be configured receive and localize various samples (e.g., one or more cell, cellular tissue, and so forth). In some implementations, the sample(s) may be dispensed, for example, in the form of one or more cell, cell tissue, and / or cell suspension. In other implementations, the sample(s) may include various cells immersed or submerged in a culture medium. In yet other implementations, the sample(s) may include one or more live cell, tissue, and so forth. For example, the sample may include live human brain tissue, such as brain tissue obtained from a neurosurgical resection from a brain tumor and / or epilepsy case.

[0064] As indicated by process block 604, a magnetic measurement apparatus may then be controlled (e.g., using a controller, as described) to perform one or more magnetic field measurement on a sample using a magnetic probe (e.g., a tuning fork, as described). The magnetic field measurement may include acquiring one or more magnetic signal from the sample(s). To acquire magnetic signal(s), the magnetic probe of an MFM system or MFM module may be driven at a driving frequency or resonance frequency between approximately 30 kHz and approximately 300 kHz, as described. For instance, the magnetic probe may be driven using an actuator system connected to the magnetic probe. The magnetic probe may be positioned and / or brought in proximity to the sample(s), for instance, using the actuator system (e.g., piezo-actuator). As described, the magnetic probe may be brought to a predetermined distance from the sample(s) (e.g., less than 1 micrometer, less than 100 nanometer, less than 10 nanometer, and so forth). For example, the magnetic probe may be approached continuously and / or progressively (e.g., in predetermined vertical steps) to the predetermined distance. In some configurations, the magnetic probe may be configured and / or positioned approach the sample from below the second surface of the base of the sample substrate, thereby sensing a magnetic field in or about the sample through the membrane of the sample substrate.

[0065] Once positioned, the magnetic probe may then be scanned laterally, along one or more transverse direction, for instance, using the actuator system, to sense various magnetic field at various positions along or about the sample substrate. In some implementations, magnetic signals acquired may be in the form of amplitude, phase, and / or shifts of the magnetic probe relative to the resonance frequency or the driving frequency. To this end, the magnetic signals may be processed to obtain one or more magnetic field value. In some implementations, various magnetic signals and / or magnetic field values may be analyzed and / or assembled to generate a representation indicating one or more magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe.- 15 -4908-8500-3894Atomey Docket No. 065472-000982W02T

[0066] An electrical measurement apparatus may also be controlled (e.g., using a controller, as described) to perform one or more electrical measurement on a sample, as indicated by process block 606. The electrical measurement(s) may be made on the sample measured using the magnetic measurement apparatus or on a different sample. In some implementations, an electrical measurement may be made on the sample, for example, using a patch-clamp technique, as described. In some implementations, electrical measurement may be performed or aided by imaging. For instance, an optical system, or component therein, may be positioned to allow an imaging of the sample. For example, imaging optics (e.g., a condenser) may be positioned above the sample receptacle to receive light (e.g., from a light source a light source positioned below the sample receptacle) transmitted through the membrane forming the sample receptacle. In this manner, the sample may be visualized and / or imaged, to allow, for instance, positioning of instrumentation and / or performance of the electrical measurement(s).

[0067] While the electrical measurement(s) may be made at any time in the process 600, in some implementations, one or more electrical measurements may be obtained simultaneous or concomitant with one or more magnetic field measurement performed at process block 604. In this manner, various correlated magnetic field and electrical measurements may be obtained, as described. Also, in some implementations, the magnetic probe of the MFM system or MFM probe may be used to perturb a magnetic field in or about the sample(s). For instance, driving the magnetic probe at the resonant frequency or another driving frequency may be used to apply a controlled magnetic field in or about the sample(s). In one example, the magnetic probe may be controlled to inject or ramp current into a cell to drive an action potential in the cell. In some implementations, the action potential may be aligned to one or more magnetic field measurements obtained, as described.

[0068] A report may be also generated at step at process block 608. The report may be in any form (e.g., graphics, graph, table, image, listing, and so, forth) and include any signals, data, and information. For example, the report may include a representation indicating one or more magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe, as described. In some implementations, the report may include one or more correlated electric and magnetic field measurement, as described herein.

[0069] Fundamentally, the magnitude of the magnetic fields generated by neuronal activity is unknown, which makes it difficult to know a priori which sensitivity is required to detect those fields. Also, the functional consequences that activity-dependent neuronal magnetic fields impart may be profound, and may have implications ranging from magnetic sensitivity- 16 -4908-8500-3894Atomey Docket No. 065472-000982W02T of molecular function to cellular growth, differentiation, and integration, to macroscopic scales where traveling electromagnetic waves impact cognitive function. Activity-dependent fluctuations of ionic capacitive layers at a plasma membrane surface that produce currents and magnetic fields could significantly influence molecular signaling cascades in the juxta- membrane domain. Moreover, it is currently unknown if polyelectrolyte cytoskeletal structures such as microtubules and actin filaments within neurons can operate as electromagnetic propagation substrates, transmitting signals along the branched structure of neuronal dendrites and axons.

[0070] Analogous to a membrane-electrolyte interface where a Helmholtz layer forms, intracellular polyelectrolytes, like the cytoskeleton, also give rise to capacitive layers. Specifically, the possibility that the branched structure of the cytoskeleton can operate as a conductive network would have far reaching implications for dendritic integration beyond cable theory, and how computations are implemented in the brain. Therefore, the presently described approach provides a novel approach for investigating such mechanisms.

[0071] Unlike electric fields, spatial propagation of magnetic fields need not be restricted by local cancelation of field propagation. This property of magnetic fields to propagate relatively unimpeded indicates that endogenously generated magnetic fields may have a more significant impact on neural activity and brain function than previously considered through magneto-ephaptic interactions that could influence neuronal oscillations and coherence. Critically, to design the next generation of magnetic stimulation devices that enable cellular specificity, the magnetic field strength required to modulate cellular function must be determined. Systems described in the present disclosure can provide such vital information to devise strategies that can precisely stimulate, or interfere with neural activity for therapeutic purposes.

[0072] As appreciated from description herein, the present approach can be applied in various applications. For instance, in some applications, systems and methods described herein may be used to evaluate efficacy of each measurement modality in nanoscale magnetophysiology. In other applications, the present approach may be used to perform a comparative analysis, for instance, using samples of rodent and human neocortical neurons, where the analysis can characterize similarities and / or differences in magneto-physiological attributes. Such comparison would be valuable considering that human neurons are much larger than rodent neurons and therefore have the capability to generate significantly larger activitydependent magnetic fields due to increased cell surface area, and hence capacity for larger- 17 -4908-8500-3894Atorney Docket No. 065472-000982W02T currents to arise from fluctuations of ionic species with capacitive layers at the membraneelectrolyte interface.

[0073] In some applications, primary neural cultures may be made using postnatal (e.g., day 0-1) rodents using various culturing techniques. Also, live human brain tissue samples can be obtained from neurosurgical resections of, for example, brain tumor and epilepsy cases, and used to make primary cell cultures. For example, a custom designed cart with an oxygenated artificial cerebrospinal fluid perfusion system may be brought to an operating room for collecting live tissue samples and maintaining tissue integrity during transport. Using such tissues samples, various aspects may be investigated, such as magnitude, dynamics, and spatial distribution of magnetic fields generated by action potentials as well as the magnetic field strength needed to modify neural activity for a given cell type.

[0074] Current techniques used to measure magnetic fields in the brain are limited to macroscale magnetic fields that reflect neuronal activity across large regions of the brain. By contrast, the present approach allows for measurement of magnetic fields generated by neuronal, and other cell, activity with high sensitivity and resolution. In addition, systems and methods disclosed herein can be used to investigate functional consequences of magnetic fields generated by neuronal activity at cellular resolution.

[0075] And so, the present disclosure provides several key innovations over conventional approaches. For instance, one of the main difficulties encountered by previous techniques is the ability to position a measurement device close enough to a cell to detect magnetic field therein. In particular, an activity-dependent neuronal magnetic field can occur at a membraneelectrolyte interface of a cell, where the interface includes solvated ions organized into capacitive layers at rest. During voltage fluctuations induced by an action potential, a rapid reorganization of charged species in such layers can give rise to currents in a juxta-membrane domain. While a magnitude of magnetic field resulting from such capacitive current may turn be small, a distance over which such magnetic fields can vary may be micrometers or nanometers, meaning that a magnetic field gradient can be quite significant. In this scenario, the present approach allows for capturing such steep magnetic field gradient, allowing for characterization of cell function. Moreover, the present approach allows for stimulating cell tissue or cells by way of magnetic field perturbation.

[0076] Although the application has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the embodiments of the application extend beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and modifications and equivalents thereof.- 18 -4908-8500-3894Atomey Docket No. 065472-000982W02T

[0077] In some embodiments, the terms “a” and “an” and “the” and similar references used in the context of describing a particular embodiment of the application (especially in the context of certain of the following claims) can be construed to cover both the singular and the plural. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (for example, “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the application and does not pose a limitation on the scope of the application otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the application.

[0078] In some embodiments, use of the terms “about” and “approximately” in context or relation to a nominal value is intended to include the nominal value as well as values that differ from the nominal value by up to 10%, either positively or negatively.

[0079] Certain embodiments of this application are described herein, including the best mode known to the inventors for carrying out the application. Variations on those certain embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. It is contemplated that skilled artisans can employ such variations as appropriate, and the application can be practiced otherwise than specifically described herein. Accordingly, many embodiments of this application include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the application unless otherwise indicated herein or otherwise clearly contradicted by context.

[0080] It is to be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of the application. Other modifications that can be employed can be within the scope of the application. Thus, by way of example, but not of limitation, alternative configurations of the embodiments of the application can be utilized in accordance with the teachings herein. Accordingly, embodiments of the present application are not limited to that precisely as shown and described.

[0081] One or more elements or aspects or steps, or any portion(s) thereof, from one or more of any of claims or Alternative Implementations below can be combined with one or more- 19 -4908-8500-3894Atomey Docket No. 065472-000982W02T elements or aspects or steps, or any portion(s) thereof, from one or more of any of the other claims or Alternative Implementations or combinations thereof, to form one or more additional implementations and / or claims of the present disclosure.

[0082] ALTERNATIVE IMPLEMENTATIONS

[0083] Alternative Implementation 1. A system for investigating a cell, the system comprising: a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base; a magnetic measurement apparatus operable to perform a magnetic field measurement on a sample comprising a cell localized in the sample receptacle, the magnetic measurement apparatus comprising: a magnetic probe having a resonant frequency; an actuator system, connected to the magnetic probe, that drives the magnetic probe at a driving frequency or at the resonant frequency to sense a magnetic field in or about the sample; and an electrical measurement apparatus operable to perform an electrical measurement on the sample.

[0084] Alternative Implementation 2. The system of Alternative Implementation 1, wherein the membrane is non-magnetic.

[0085] Alternative Implementation 3. The system of Alternative Implementation 1, wherein the membrane is transparent.

[0086] Alternative Implementation 4. The system of any one of Alternative Implementations 1 to 3, wherein the membrane is a silicon nitride membrane with a thickness between approximately 10 nm and approximately 40 nanometers.

[0087] Alternative Implementation 5. The system of any one of Alternative Implementations 1 to 4, wherein the magnetic measurement apparatus is arranged below the second surface of the base, wherein the magnetic probe senses the magnetic field in or about the sample through the membrane.

[0088] Alternative Implementation 6. The system of any one of Alternative Implementations 1 to 5, wherein the system further comprises a controller operable to direct the magnetic measurement apparatus perform the magnetic field measurement on the sample.

[0089] Alternative Implementation 7. The system of Alternative Implementation 6, wherein the controller directs the actuator system to control the driving frequency of a magnetic probe, a vertical approach or a vertical position of the magnetic probe, a lateral scan of the magnetic probe, or a combination thereof.

[0090] Alternative Implementation 8. The system of Alternative Implementation 6 or Alternative Implementation 7, wherein the controller is further operable to analyze signals produced by the magnetic measurement apparatus to generate a representation of one or more- 20 -4908-8500-3894Atorney Docket No. 065472-000982W02T magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe.

[0091] Alternative Implementation 9. The system of any one of Alternative Implementations 6 to 8, wherein the controller is further operable to control the magnetic probe to provide an applied magnetic field in or about the sample.

[0092] Alternative Implementation 10. The system of any one of Alternative Implementations 1 to 9, wherein the electrical measurement apparatus is further operable to inject current into the sample to drive an action potential in the sample to generate the magnetic field in the sample.

[0093] Alternative Implementation 11. The system of any one of Alternative Implementations 1 to 10, wherein the electrical measurement apparatus further comprises a patch-clamp pipette comprising a conducting solution, an electrode electrically connected to the conducting solution, an operational amplifier connected to the conducting solution, one or more feedback resistor connected to the conducting solution, and a measurement device connected to the feedback resistor and operational amplifier.

[0094] Alternative Implementation 12. The system of Alternative Implementation 11, wherein the system further comprises an optical system operable to image the sample in the sample receptacle.

[0095] Alternative Implementation 13. A method for investigating a cell, the method comprising: providing a system that comprises a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base; controlling a magnetic measurement apparatus of the system to perform a magnetic field measurement on a sample using a magnetic probe, wherein the sample comprises a cell localized in the sample receptacle; controlling an electrical measurement apparatus of the system to perform an electrical measurement on the sample; and generating a report indicative of the magnetic field measurement and electrical measurement on the sample.

[0096] Alternative Implementation 14. The method of Alternative Implementation 13, wherein the method further comprises driving, using an actuator system, the magnetic probe at a driving frequency or at a resonant frequency of the magnetic probe to sense magnetic field in or about the sample.

[0097] Alternative Implementation 15. The method of Alternative Implementation 14, wherein the method further comprises controlling the actuator system to approach the sample from below the second surface of the base to sense magnetic field in or about the sample- 21 -4908-8500-3894Atomey Docket No. 065472-000982W02T through the membrane.

[0098] Alternative Implementation 16. The method of Alternative Implementation 14 or Alternative Implementation 15, wherein the method further comprises directing, using a controller, the actuator system to control the driving frequency of a magnetic probe, a vertical approach or a vertical position of the magnetic probe, a lateral scan of the magnetic probe, or a combination thereof.

[0099] Alternative Implementation 17. The method of any one of Alternative Implementations 14 to 16, wherein the method further comprises directing, using a controller, the actuator system to apply magnetic field in or about the sample.

[0100] Alternative Implementation 18. The method of any one of Alternative Implementations 13 to 17, wherein the method further comprises controlling the electrical measurement apparatus to apply a patch-clamp technique to perform an electrical measurement on the sample.

[0101] Alternative Implementation 19. The method of any one of Alternative Implementations 13 to 18, wherein the method further comprises coordinating the magnetic field measurement and the electrical measurement of the sample.

[0102] Alternative Implementation 20. The method of any one of Alternative Implementations 13 to 19, wherein the method further comprises analyzing signals produced by the magnetic measurement apparatus to generate a representation indicating one or more magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe, and providing the representation in the report.- 22 -4908-8500-3894

Claims

Atorney Docket No. 065472-000982W02TCLAIMS1. A system for investigating a cell, the system comprising: a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base; a magnetic measurement apparatus operable to perform a magnetic field measurement on a sample comprising a cell localized in the sample receptacle, the magnetic measurement apparatus comprising: a magnetic probe having a resonant frequency; an actuator system, connected to the magnetic probe, that drives the magnetic probe at a driving frequency or at the resonant frequency to sense a magnetic field in or about the sample; and an electrical measurement apparatus operable to perform an electrical measurement on the sample.

2. The system of claim 1, wherein the membrane is non-magnetic.

3. The system of claim 1, wherein the membrane is transparent.

4. The system of claim 1, wherein the membrane is a silicon nitride membrane with a thickness between approximately 10 nm and approximately 40 nanometers.

5. The system of claim 1, wherein the magnetic measurement apparatus is arranged below the second surface of the base, wherein the magnetic probe senses the magnetic field in or about the sample through the membrane.

6. The system of claim 1, wherein the system further comprises a controller operable to direct the magnetic measurement apparatus perform the magnetic field measurement on the sample.

7. The system of claim 6, wherein the controller directs the actuator system to control the driving frequency of a magnetic probe, a vertical approach or a vertical position of the magnetic probe, a lateral scan of the magnetic probe, or a combination thereof.- 23 -4908-8500-3894Atomey Docket No. 065472-000982W02T8. The system of claim 6, wherein the controller is further operable to analyze signals produced by the magnetic measurement apparatus to generate a representation of one or more magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe.

9. The system of claim 6, wherein the controller is further operable to control the magnetic probe to provide an applied magnetic field in or about the sample.

10. The system of claim 1 , wherein the electrical measurement apparatus is further operable to inject current into the sample to drive an action potential in the sample to generate the magnetic field in the sample.

11. The system of claim 1, wherein the electrical measurement apparatus further comprises a patch-clamp pipette comprising a conducting solution, an electrode electrically connected to the conducting solution, an operational amplifier connected to the conducting solution, one or more feedback resistor connected to the conducting solution, and a measurement device connected to the feedback resistor and operational amplifier.

12. The system of claim 1, wherein the system further comprises an optical system operable to image the sample in the sample receptacle.

13. A method for investigating a cell, the method comprising: providing a system that comprises a sample substrate having a base with a first surface and a second surface, and a sample receptacle formed by an opening in the base and a membrane that spans the opening in the base; controlling a magnetic measurement apparatus of the system to perform a magnetic field measurement on a sample using a magnetic probe, wherein the sample comprises a cell localized in the sample receptacle; controlling an electrical measurement apparatus of the system to perform an electrical measurement on the sample; and generating a report indicative of the magnetic field measurement and electrical measurement on the sample.- 24 -4908-8500-3894Atorney Docket No. 065472-000982W02T14. The method of claim 13, wherein the method further comprises driving, using an actuator system, the magnetic probe at a driving frequency or at a resonant frequency of the magnetic probe to sense magnetic field in or about the sample.

15. The method of claim 14, wherein the method further comprises controlling the actuator system to approach the sample from below the second surface of the base to sense magnetic field in or about the sample through the membrane.

16. The method of claim 14, wherein the method further comprises directing, using a controller, the actuator system to control the driving frequency of a magnetic probe, a vertical approach or a vertical position of the magnetic probe, a lateral scan of the magnetic probe, or a combination thereof.

17. The method of claim 14, wherein the method further comprises directing, using a controller, the actuator system to apply magnetic field in or about the sample.

18. The method of claim 13, wherein the method further comprises controlling the electrical measurement apparatus to apply a patch-clamp technique to perform an electrical measurement on the sample.

19. The method of claim 13, wherein the method further comprises coordinating the magnetic field measurement and the electrical measurement of the sample.

20. The method of claim 13, wherein the method further comprises analyzing signals produced by the magnetic measurement apparatus to generate a representation indicating one or more magnetic field value in or about the sample, a spatial distribution of magnetic field values in or about the sample, or both, sensed using the magnetic probe, and providing the representation in the report.- 25 -4908-8500-3894

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