Method and apparatus for determining physiological parameters

Abstract

An apparatus (100) for determining a physiological parameter is disclosed, the apparatus comprising an elongated magnetic probe (102, 610, 702), a drive coil (104) surrounding the magnetic probe, a measurement coil (106, 602, 708, 1004) having at least a first section and a second section, and a controller (108). The controller is configured to energize the drive coil to generate a magnetic force to initiate movement of the magnetic probe towards an end (102A) of the magnetic probe, measure a first induced voltage value and a common induced voltage value, determine locator values ​​as a function of time, map the locator values ​​from the time domain to a spatial domain, calculate a velocity profile of the magnetic probe from the locator values ​​in the spatial domain, and determine the physiological parameter using the calculated velocity profile.

Description

[Technical Field]

[0001] The matters disclosed herein (hereinafter referred to as "this disclosure") relate in general to ophthalmic treatment devices, and more specifically to methods and systems for determining physiological parameters. Background

[0002] Aqueous humor is a clear, watery fluid produced within the eye to protect the lens and maintain intraocular fluid pressure. This intraocular pressure is known as intraocular pressure (IOP). IOP is a physiological parameter that determines the strength of the eyeball and can detect signs of optic nerve damage that may affect vision. Normal IOP has diurnal variations and individual differences. However, if IOP is consistently too high or too low, vision problems may arise.

[0003] Traditionally, intraocular pressure (IOP) testing involved measuring the pressure inside the eye. This test measured the firmness of the eyeball using a tonometer. Traditionally, the Goldman Applanation Tonometer (GAT) involved anesthetizing the eye with a numbing agent and introducing a small amount of non-toxic dye into the eye. Then, a small probe gently touched the surface of the eyeball, and the IOP was measured. IOP is measured based on the force required to gently flatten a certain area of ​​the eyeball surface. However, the thickness of the eyeball, its elasticity, and the amount of non-toxic dye used can cause errors and affect the accuracy of the measurement. The Perkins Applanation Tonometer (PAT) is also used for IOP measurement. The PAT is an ergonomically designed, easy-to-use handheld tonometer. However, operating the PAT requires a high level of skill. Because it is a handheld tonometer, it has low stability, and because it requires topical application of fluorescein and anesthetic, there is a possibility of scratching the surface of the eyeball.

[0004] Tonopen is a type of rebound tonometry device used to measure intraocular pressure. Tonopen requires an anesthetic to numb the eye. It features a probe that bounces off the surface of the eye to measure pressure. The probe used has a conical shape. This conical shape can potentially cause small scratches on the surface of the eyeball.

[0005] In light of these circumstances, there is a need to overcome the aforementioned shortcomings associated with conventional methods related to the measurement of physiological parameters. Abstract

[0006] This disclosure aims to provide an apparatus for determining physiological parameters. This disclosure also aims to provide a method for determining physiological parameters. The object of this disclosure is to provide a solution that overcomes, at least partially, the problems encountered in the prior art.

[0007] One interpretation is that this disclosure provides an apparatus for determining physiological parameters. This apparatus is An elongated magnetic probe having a first end, a second end opposite to the first end, and an intermediate portion between the first end and the second end; A drive coil is positioned so as to partially surround the magnetic probe; A measuring coil having at least a first section and a second section, and positioned to partially surround the magnetic probe; Controller and; The controller is equipped with, - To initiate the movement of the magnetic probe toward the first end, the drive coil is selectively energized to generate a magnetic force; - Measuring, as a function of time, a first induced voltage value and a common induced voltage value while the magnetic probe is moving, wherein the first induced voltage value is the voltage across the first section, and the common induced voltage value is a voltage value spanning from the first section to the second section, or a voltage value across at least one of the second sections; The locator value is determined as a function of time by dividing the first induced voltage value by the common induced voltage value; • Mapping the aforementioned locator value from the time domain to the spatial domain as a function of time; The first velocity profile of the magnetic probe is calculated from the spatial domain locator value, and the physiological parameters are determined using the calculated first velocity profile; It is configured to perform the following.

[0008] Alternatively, this disclosure provides a method for determining physiological parameters. This method is • To move the elongated magnetic probe toward the first end of the magnetic probe, current is applied to the drive coil; • With respect to the first section of the measuring coil, measure the induced first voltage as a function of time; - Measuring, as a function of time, an induced common voltage which is either a voltage spanning the first section and the second section of the measuring coil, or a voltage applied to the second section; The first locator value is determined as a function of time by dividing the measured induced voltage value by the measured common induced voltage value; • Mapping the aforementioned first locator value from the time domain to the spatial domain; • Calculating the first velocity profile of the magnetic probe from the first locator value in the spatial domain; • Determining physiological parameters using the first velocity profile; Includes.

[0009] Embodiments of the present disclosure substantially resolve, or at least partially resolve, the aforementioned problems in the prior art, and enable the precise determination of the position of a magnetic probe by calculating the induced voltage.

[0010] Further aspects, advantages, features, and objectives of what is disclosed herein will be made apparent by the accompanying drawings and the detailed description of exemplary embodiments, which shall be interpreted together with the accompanying claims.

[0011] It will also be understood that a feature of this disclosure is that it can be combined in various ways without departing from the scope defined by the attached claims. [Brief explanation of the drawing]

[0012] The above summary and the following detailed description of exemplary embodiments will be better understood in conjunction with the accompanying drawings. For illustrative purposes, exemplary configurations of the disclosure are shown in the drawings. However, the disclosure is not limited to the specific methods and apparatus disclosed herein. The scale of the drawings is not accurate. Similar elements are indicated by the same number whenever possible. Hereinafter, embodiments of the present disclosure will be described with reference to the following drawings as an example. [Figure 1] This is a block diagram of a system for an apparatus for determining physiological parameters according to one embodiment of the present disclosure. [Figure 2] This graph shows the force induced on a magnetic probe per ampere of current in a signal coil or drive coil, relative to its position in millimeters. [Figure 3] This graph shows the common induced voltage of the measuring coil. [Figure 4] This diagram shows the measurement of three locator signals using four differential amplifiers to measure the voltage across each signal coil segment. [Figure 5] This is a graph for determining the position of an elongated magnetic probe in one of the implementations of this disclosure. [Figure 6] A measurement coil assembly according to an implementation of the present disclosure. [Figure 7] A schematic diagram of a system of a robotic system for determining the speed and position of an elongated magnetic probe according to an implementation of the present disclosure. [Figure 8] An electrical circuit for adding induced voltages according to an implementation of the present disclosure. [Figure 9] An induced signal voltage of a measurement coil according to an implementation of the present disclosure. [Figure 10] A block diagram of a system for a basic implementation of an apparatus according to an embodiment of the present disclosure. [Figure 11A] A graph for realizing an optimal connection between a first amplifier and a second amplifier according to an implementation of the present disclosure. [Figure 11B] A graph for realizing an optimal connection between a first amplifier and a second amplifier according to an implementation of the present disclosure. [Figure 12A] A graph showing signal voltage and common induced voltage values according to an implementation of the present disclosure. [Figure 12B] A graph showing signal voltage and common induced voltage values according to an implementation of the present disclosure. [Figure 13A] A graph for measuring a locator value by adding a plurality of signal amplifiers according to an implementation of the present disclosure. [Figure 13B] A graph for measuring a locator value by adding a plurality of signal amplifiers according to an implementation of the present disclosure. [Figure 13C] A graph for measuring a locator value by adding a plurality of signal amplifiers according to an implementation of the present disclosure. [Figure 13D] A graph for measuring a locator value by adding a plurality of signal amplifiers according to an implementation of the present disclosure. [Figure 14A] A flowchart showing steps of a method for determining a physiological parameter according to an embodiment of the present disclosure. [Figure 14B]A flowchart illustrating the steps of a method for determining physiological parameters according to embodiments of this disclosure is shown. [Figure 15] This is an explanatory diagram regarding the determination of speed profiles. In the attached diagram, underlined numbers are used to represent the item at the location where the number is written or an item adjacent to that number. Ununderlined numbers are associated with the item identified by the line extending from that number. When a number is written without an underline and accompanied by an arrow, that number is used to identify the general item indicated by the arrow. Detailed description of the embodiment

[0013] The following detailed description illustrates embodiments of the disclosure and methods by which they may be implemented. While several forms for implementing the disclosure have been disclosed, those skilled in the art will recognize that other forms for implementing the disclosure are also possible.

[0014] According to one interpretation, one embodiment of the present disclosure provides an apparatus for determining physiological parameters. This apparatus is An elongated magnetic probe having a first end, a second end opposite to the first end, and an intermediate portion between the first end and the second end; A drive coil is positioned so as to partially surround the magnetic probe; A measuring coil having at least a first section and a second section, and positioned to partially surround the magnetic probe; Controller and; The controller is equipped with, - To initiate the movement of the magnetic probe toward the first end, the drive coil is selectively energized to generate a magnetic force; - Measuring, as a function of time, a first induced voltage value and a common induced voltage value while the magnetic probe is moving, wherein the first induced voltage value is the voltage across the first section, and the common induced voltage value is a voltage value spanning from the first section to the second section, or a voltage value across at least one of the second sections; The locator value is determined as a function of time by dividing the first induced voltage value by the common induced voltage value; • Mapping the aforementioned locator value from the time domain to the spatial domain as a function of time; The first velocity profile of the magnetic probe is calculated from the spatial domain locator value, and the physiological parameters are determined using the calculated first velocity profile; It is configured to perform the following.

[0015] Preferably, the measurement of the voltage value from the first section is performed simultaneously with the measurement of the common induced voltage. The common induced voltage can be measured across the first and second sections; that is, it can be measured as the sum of the voltages from the first and second sections. Alternatively, the common induced voltage can be measured as the voltage of the second section. The second section may overlap the first section. Before calculating the probe speed-independent locator signal, multiple sections of the measuring coil can be used to combine these signal voltages in various ways. In some embodiments, the measurement of the first section is performed first, and the measurement of the common induced voltage is performed in the other measurement cycle. A common start time (t0) based on relative time is defined as the start time for each measurement.

[0016] According to another interpretation of this disclosure, this disclosure provides a method for determining physiological parameters. This method is • To move the elongated magnetic probe toward the first end of the magnetic probe, current is applied to the drive coil; • With respect to the first section of the measuring coil, measure the induced first voltage as a function of time; - Measuring, as a function of time, an induced common voltage which is either a voltage spanning the first section and the second section of the measuring coil, or a voltage applied to the second section; The first locator value is determined as a function of time by dividing the measured first induced voltage value by the measured common induced voltage value; • Mapping the aforementioned first locator value from the time domain to the spatial domain; • Calculating the first velocity profile of the magnetic probe from the first locator value in the spatial domain; • Determining physiological parameters using the first velocity profile; Includes.

[0017] The speed and magnetization of the elongated magnetic probe are determined, which allows for more accurate measurements.

[0018] This disclosure provides an apparatus for determining physiological parameters, which may refer to an instrument that can be used to measure physiological parameters of the eye. These physiological parameters may be, for example, intraocular pressure or tactile sensitivity of the eye. In some embodiments, the apparatus is a tonometer. A tonometer is used to measure intraocular pressure from ophthalmic measurements. Intraocular pressure is calculated from a voltage signal that represents (as a function of time) the velocity of an elongated magnetic probe bounced off the surface of the eyeball. The magnitude of the signal depends on the magnetic force and velocity of the elongated magnetic probe.

[0019] The device comprises an elongated magnetic probe having a first end, a second end opposite to the first end, and an intermediate portion between the first and second ends. The first end of the elongated magnetic probe is made of a biocompatible material and strikes the surface of the eye during use. The fact that the first portion is made of a biocompatible material is beneficial, as it allows the probe to function in direct contact with the biological tissue of the eyeball, minimizing discomfort and pain. It should be noted that the biocompatible material is non-carcinogenic, non-toxic, and corrosion-resistant. The elongated magnetic probe may also be made of a thin wire of magnetic material. The elongated magnetic probe may be, for example, 20 millimeters long and 0.5 millimeters wide. The magnetic material of the elongated magnetic probe may be ferromagnetic. An induced voltage is generated when the elongated magnetic probe moves within the measuring coil. However, the magnetic force of the elongated magnetic probe is very small. The elongated magnetic probe is pushed back only by the surface of the eye, and no other force is present to push it back.

[0020] This device has a drive coil positioned to partially surround an elongated magnetic probe. This drive coil positions the elongated magnetic probe as a movable loop. The drive coil also has a finite number of loops. The drive coil can be positioned along any point between a first end and a second end of the magnetic probe. For example, the drive coil can be positioned close to the first end. When current is passed through the drive coil, it moves the elongated magnetic probe. The drive coil pulls the elongated magnetic probe, causing it to protrude toward the surface of the eyeball at a speed equal to the product of the current supplied through the drive coil and the magnetization of the elongated magnetic probe.

[0021] The apparatus comprises a measuring coil having at least a first section and a second section. The measuring coil is positioned to partially surround a magnetic probe. The measuring coil has a finite number of loops. The total number of loops in the measuring coil is divided between the first section and the second section. Each of the first and second sections may have at least one loop through which an elongated magnetic probe can move. The elongated magnetic probe may also move along an intermediate section between the first and second sections. Because the measuring coil has two or more sections, it is possible to simultaneously measure different voltage profiles induced by the movement of the elongated magnetic probe. The technical effect of this is to eliminate the uncertainty of the magnetization constant of the probe. In fact, as will be described later, by performing measurements using at least two different measuring coils, the probe speed can be determined even if the magnetization value is not known at all.

[0022] In some embodiments, the measuring coil is used as a drive coil for a first period and as a second section of the measuring coil in a second period following the first period. Here, the measuring coil is used to conduct current, thereby inducing motion in an elongated magnetic probe. Immediately after the elongated magnetic probe has been accelerated to its operating speed, the measuring coil is used to measure the induced voltage across it. Beneficially, this reduces the number of coils in the device. The measuring coil can have multiple functions, depending on how the controller controls it, such as conducting current or measuring induced voltage.

[0023] In some embodiments, the first and second sections of the measuring coil are connected in series. Here, series connection means the electrical coupling between the last loop of the first section and the first loop of the second section. Typically, measuring the voltage induced in a series-connected measuring coil can be achieved by connecting voltmeters to both the first and second sections of the measuring coil. Alternatively, the voltage induced in the first section is measured. Then, the voltages induced in both the first and second sections may be measured together to derive the total induced voltage value. The voltage induced in the second section can be calculated by subtracting the voltage induced in the first section from the total induced voltage.

[0024] In some embodiments, the measuring coil has a third section, which is connected in series with the first and second sections of the measuring coil and is positioned to surround the third section of the elongated magnetic probe. This third section may have at least one loop through which the elongated magnetic probe can move. Additional sections may be added to the measuring coil to generate more data points.

[0025] In one example, the measuring coil is divided into a first section, a second section, a third section, and a fourth section. The drive coil has one section. Coupling leads are wired at the points where the first, second, third, and fourth sections of the measuring coil are connected to each other. The first coupling lead is connected to the left end of the first section, the second coupling lead is connected to the connection between the first and second sections, the third coupling lead is connected to the connection between the second and third sections, the fourth coupling lead is connected to the connection between the third and fourth sections, and the fifth coupling lead is connected to the right end of the fourth section. An exemplary implementation of such a measuring coil is shown in more detail in Figure 6.

[0026] This device has a controller. The controller is a computing device that can operate to process information in response to it. For example, the controller may be an embedded microcontroller, a microprocessor, a computer, or a portable computing device. The controller is communicatively coupled to the measuring coil and the drive coil. The controller energizes the drive coil to move the elongated magnetic probe toward the surface of the eyeball.

[0027] The controller is configured to selectively energize the drive coil to generate a magnetic force that initiates movement of the elongated magnetic probe toward its first end. Selective energization means switching the power supply voltage of the drive coil ON / OFF. When the power supply voltage of the drive coil is switched ON, an electric field is generated. Generally, a higher power supply voltage of the drive coil results in a stronger magnetic force. As a result, the acceleration of the elongated magnetic probe increases. The magnetic force is a function of the magnetization of the elongated magnetic probe. Here, magnetization refers to the strength of the magnetization of the elongated magnetic probe. A higher magnetization results in a stronger magnetic force. By selectively energizing the drive coil, the elongated magnetic probe can be moved toward the surface of the eyeball. If the polarity of the drive coil is reversed by selective energization, the elongated magnetic probe will move in the opposite direction. The elongated magnetic probe can move in any direction that can be controlled by the controller, whenever necessary. Here, the voltage is a function of the velocity and magnetization of the elongated magnetic probe. The velocity of the elongated magnetic probe is continuously monitored as a function of time by the measuring coil. Such information regarding the velocity of the elongated magnetic probe can be used to determine the pressure of the eye, which can be used for diagnostic purposes. When current is supplied to the drive coil, a magnetic field is induced in the drive coil. The magnetic field is proportional to the current and the finite number of loops in the drive coil. The magnetic field can be controlled by controlling the current supplied to the drive coil. The magnetic field generates a magnetic force applied to the elongated magnetic probe. This magnetic force is a function of the magnetization of the elongated magnetic probe. The acceleration of the elongated magnetic probe can be calculated by dividing the mass of the elongated magnetic probe by the force applied to it. Thus, the elongated magnetic probe is accelerated by the current pulses of the drive coil. That is, the magnetic field generated by the current pulses of the drive coil acts on the magnetic probe, accelerating its movement. The elongated magnetic probe travels through the measuring coil toward the surface of the eyeball and bounces off the surface of the eyeball. One of the technical problems when performing the above measurements is the uncertainty in the magnetization value. In fact, comparing two probes from different manufacturing patches (for example, those from different manufacturing dates or times) can result in significant differences in the probe's magnetization value and magnetizing capability. This leads to uncertainty when measuring the induced voltage. Since the probe speed is a function of the probe's magnetization value, for example, the probe's movement can be faster even with the same driving voltage (current).

[0028] In some embodiments, a magnetization cycle can be incorporated into this disclosure for the magnetization of an elongated magnetic probe. Here, the magnetization cycle is achieved by current pulses in a drive coil and a measuring coil, respectively. These current pulses pull the elongated magnetic probe back and forth within the apparatus. The magnetization cycle may be terminated by a calibration cycle. The calibration cycle collects information necessary to set the degree of acceleration by the drive coil to a value that will yield the optimal speed of the elongated magnetic probe. The calibration cycle checks both the apparatus and the elongated magnetic probe before determining physiological parameters. In some embodiments, the calibration cycle can be used to collect (multiple) lookup table values ​​for mapping (multiple) locator values ​​as a function of time from the time domain to the spatial domain.

[0029] In this embodiment, during use, the first section of the measuring coil surrounds the first section of the elongated magnetic probe, and the second section of the measuring coil surrounds the second section of the elongated magnetic probe. When the elongated magnetic probe is in a first spatial position, the first section of the elongated magnetic probe is distinct from the second section of the elongated magnetic probe. In the geometric setup of the apparatus, the first spatial position is the initial position of the elongated magnetic probe before it is selectively energized. In the first position, the elongated magnetic probe is fully housed within the apparatus.

[0030] In some embodiments, when the elongated magnetic probe is in a second spatial position during use, the first section of the measuring coil does not surround the first section of the elongated magnetic probe, while the second section of the measuring coil surrounds the second section of the elongated magnetic probe. Here, the second spatial position is different from the first spatial position. The second spatial position is, for example, when the elongated magnetic probe has moved to its end position, for example, a position almost completely away from the measuring coil. In this case, since the first section of the measuring coil does not surround the elongated magnetic probe at all, the change in magnetic flux on the measuring coil is larger compared to a measuring coil that partially surrounds the elongated magnetic probe. In a uniformly magnetized elongated magnetic probe, the magnetic flux is constant throughout. The magnetic flux lines leave one end and re-enter from the opposite end. Some of the magnetic flux lines pass through the wall of the measuring coil and re-enter from the opposite end. Furthermore, because the elongated magnetic probe is long and very close to the measuring coil, the magnetic flux on the measuring coil changes with time with each turn.

[0031] The current in the measuring coil acts on an elongated magnetic probe with a controlled magnetic field pulse, sending the probe to the surface of the eyeball at a desired speed. The speed of the elongated magnetic probe is determined by the amplitude of the current pulse, the length and magnetization of the elongated magnetic probe, and the friction between the elongated magnetic probe and the measuring and driving coils. The elongated magnetic probe bounces back when it hits the surface of the eyeball. Intraocular pressure can be determined by measuring the velocity profile of the elongated magnetic probe as it approaches, bounces back, and / or returns.

[0032] The controller is configured to measure, as a function of time, the (multiple) first induced voltage values ​​from the first section and the (multiple) common induced voltage values ​​from the first section during the movement of the elongated magnetic probe. As the elongated magnetic probe moves through the loop of the first and second sections, voltages are induced according to Faraday's law of induction. The controller is configured to measure, as a function of time, the (multiple) first induced voltage values ​​from the elongated magnetic probe while it moves through the first section. Furthermore, the common induced voltage of the measuring coil is measured as a function of time. When there are two sections (the first section and the second section), the common induced voltage is the induced voltage across both sections. For example, when there are three or four sections, the common induced voltage is the induced voltage across the first, second, third, and fourth sections.

[0033] In some embodiments, the sampling interval of the induced voltage and the geometric arrangement of the measuring coil are controlled by precisely controlling the position of the elongated magnetic probe using a robotic system. As the elongated magnetic probe passes through the first, second, third, and fourth sections toward the surface of the eyeball, the induced voltage changes as a function of time. The amplitude of the induced voltage is proportional to the position and velocity of the elongated magnetic probe. If the magnetization of the elongated magnetic probe is known, the common induced voltage is suitable for measuring velocity. This is explained in detail in relation to Figure 4. As explained, one of the technical problems is that the magnetization of the elongated magnetic probe can have various values, making simple calculation of velocity difficult.

[0034] Initially, while the drive coil accelerates the elongated magnetic probe, the common induced voltage (and the first induced voltage) increases. Subsequently, the elongated magnetic probe collides with the surface of the eyeball, decelerates, and becomes zero in approximately 1 millisecond (ms). This occurs after 20 to 35 milliseconds. Then the magnetic probe bounces back. These depend on the velocity of the magnetic probe and its distance from the surface of the eyeball. The deceleration of the elongated magnetic probe occurs, for example, from 20, 24, 28, or 32 milliseconds to 21, 25, 30, or 35 milliseconds. Here, the change in velocity of the magnetic probe while in contact with the surface of the eyeball depends mainly on the velocity of the magnetic probe and also on the intraocular pressure through the pushing force. The main parameter that depends on the intraocular pressure is given by the slope of the deceleration of the magnetic probe's velocity. The deceleration of the magnetic probe's velocity is equal to the magnetic force between the magnetic probe and the surface of the eyeball. Furthermore, the apparatus of this disclosure corrects and provides the output signal from an elongated magnetic probe. Intraocular pressure (IOP) is then derived from the provided signal. To generate a curve that transforms the IOP to reveal the true IOP, the output signal is validated with patient data using other types of measurements. As a result, except when the IOP is low, the IOP is equal to the input signal multiplied by a coefficient of approximately 1.5 minus a constant. The lower the IOP, the larger this coefficient and the smaller the constant. This is explained in detail in relation to Figure 3. The first and second signal amplifiers used are operational amplifiers (op-amps). The op-amps apply voltages to the negative and positive terminals of the first and second signal amplifiers via resistors at the input of the amplification stage. Furthermore, multiple induced voltage signals can be easily added to or subtracted from the common output with weights set by the resistors. Specifically, to easily implement this disclosure, a differential amplifier can be used. Here, the first input of the differential amplifier is connected to the negative terminal, and the second input of the differential amplifier is connected to the positive terminal. A basic implementation may be carried out using a first amplifier and a second amplifier. The first amplifier has multiple inputs for summing selected induced voltages from the first or second section, or, depending on the embodiment, from the third or fourth section. The second amplifier is a differential amplifier for calculating the common induced voltage. In one example, the first amplifier is electrically coupled to the second and third sections to determine the difference between the induced voltages of the second and third sections. The second amplifier is also electrically coupled to the first and fourth sections to generate the common induced voltage. In one example, the first induced voltage in the first section is referred to as "V1", the second induced voltage in the second section as "V2", and the third induced voltage in the third section as "V3". Furthermore, four resistors "R1", "R2", "R3", and "R4" are connected to the differential amplifier. In such an example, the output voltage V out It is calculated as follows:

[0035] V out =(V1·R1 / (R1+R2)+V2·R1 / (R1+R2))(1+R4 / R3)-V3·R4 / R3

[0036] To detect very small signals, V is proportional to V1-V3. out Using a differential amplifier to provide a specific signal has proven to be a practical method for eliminating interference signals. Such amplifiers are commercially available for this purpose.

[0037] Such examples will be explained in more detail with reference to Figure 8. Furthermore, by using an operational amplifier with 4 inputs or less and adjusting the sign and amplification factor with the sum resistance value, any combination of induced voltages of the measuring coil can be obtained. Furthermore, an optimized signal can be obtained by combining the output of the first amplifier and the output of the second amplifier. Here, the optimized signal may be made sensitive to requirements such as the position of an elongated magnetic probe, but insensitive to other parameters such as magnetic intensity.

[0038] The controller is configured to determine the locator value as a function of time by dividing the first induced voltage value by the common induced voltage value. The technical effect of dividing the first voltage value by the respective common induced voltage value (for each pair) is to eliminate the unknown magnetization constant of the elongated magnetic probe. The induced voltage is a function of the change in the magnetic flux Φ of the measuring coil. The magnetic flux is a function of the magnetic field B, i.e., the magnetization of the elongated magnetic probe. Since B is constant, it can be eliminated by dividing the first induced voltage by the common induced voltage value. The locator value represents a value correlated with the actual position of the elongated magnetic probe. Considering that the measurement is performed as a function of time, the locator value is initially a function of time. Therefore, the locator value is in the time domain. The first induced voltage value is divided by the common induced voltage obtained in the corresponding measurement. Experimentally, it has been found that dividing the first induced voltage coil value by the common induced voltage value yields a similar shape. Therefore, the locator value does not depend on the velocity of the elongated magnetic probe. The velocity of the elongated magnetic probe is a function of magnetization. As a result, there is no variation in the drive coil current with respect to the magnetization of the probe. Typically, to resolve the uncertainty in the magnetization of an elongated magnetic probe, a first induced voltage and a common induced voltage are measured. The first and common induced voltages are functions of the velocity and magnetization of the elongated magnetic probe. As an example, a first signal amplifier measures the common induced voltage across the entire measuring coil for a 0.2-volt (V) drive coil and a 0.3-V drive coil. Here, the common induced voltage is referred to as "U15". A second signal amplifier is electrically coupled to the second coupling lead of the second section and to the fourth coupling lead at the connection between the third and fourth sections. The voltage measured from here is referred to as "U24". Dividing "U24" by "U15" results in identical results for both the 0.2V and 0.3V drive coils, as the dependence on the drive coil amplitude is removed. The speed of the elongated magnetic probe directly affects the induced voltage. Here, the second induced voltage value increases by 1.6, and the locator value in the intermediate region remains the same within the measurement accuracy range. Voltage signals below Z = 5 mm and above Z = 10 mm are not considered. This is because the induced voltage value does not change rapidly as a function of Z, and the locator value remains constant. This point will be explained in more detail in relation to Figure 11.

[0039] Continuing from the previous example, the useful range is mostly directed to the left and also narrows. Therefore, this disclosure can be implemented upon request. The useful range can be broadened by using a fourth signal amplifier, a fifth signal amplifier, etc. This will be explained in more detail in conjunction with Figure 12. Figure 13 shows the signal collected to cover a wide area around the region of interest (ROI) when using two amplifiers. The signal U15 is measured by taking the sum of the output signals from the first signal amplifier and the output signals from the second signal amplifier. Here, the sum of the output signals from the first signal amplifier and the output signals from the second signal amplifier is called "U+". Also, the difference between the output signals from the first signal amplifier and the output signals from the second signal amplifier is called "U-". Typically, the locator value can be calculated by the ratio of the difference between the output signals from the first signal amplifier and the output signals from the second signal amplifier to the sum of the output signals from the first signal amplifier and the output signals from the second signal amplifier. That is, L = (U-) / (U+) That is the case.

[0040] The controller is configured to map voltages U13 and U35 as functions of time. Here, the time domain represents the locator value as a function of sampling time. The mapping can be performed using, for example, a lookup table. The locator value is determined experimentally for each shape of the measurement coil. This can be done, for example, by moving a long, slender magnetic probe back and forth with an actuator and simultaneously measuring the induced voltage value. Since it is moved with a drive coil, the relationship between the spatial position of the long, slender magnetic probe and the induced voltage value can be determined.

[0041] In some embodiments, the mapping from the time domain to the spatial domain is performed by at least one of a predetermined transfer function or a lookup table. The mapping of the time domain signal is performed, for example, by positioning the probe at a precise location and vibrating it with a very small displacement at a suitable frequency on the order of 1 kilohertz. The time domain signal at this location is proportional to the induced voltage at 1 kHz. This is done to calibrate the position curve. The mapping from the time domain to the spatial domain is a necessary step in determining the probe velocity. The creation of a predetermined transfer function is disclosed in Example 1 below, and an example of a method for determining a lookup table is disclosed in Example 2.

[0042] The controller is configured to calculate a first velocity profile of an elongated magnetic probe from spatial domain locator values ​​and to use the calculated first velocity profile to determine physiological parameters. The first velocity profile is calculated from time domain locator values ​​relative to spatial domain locator values. Depending on the application, velocity as a function of time is used to determine physiological parameters, such as intraocular pressure. For example, the velocity of the elongated magnetic probe and the response of the eye surface to stop the elongated magnetic probe after it has been ejected toward the eye surface can be determined by calculating the first derivative of velocity. It is also possible to determine the velocity at which the elongated magnetic probe bounces off the eye surface. If the elongated magnetic probe bounces back at a high speed, the intraocular pressure is high; if the elongated magnetic probe bounces back at a low speed, the intraocular pressure is low. Measurements of time and velocity of an elongated magnetic probe may be collected in conjunction with medical tests (e.g., clinical trials). Then, as discussed in this disclosure, a function of velocity with respect to the shape of the elongated magnetic probe may be compared with the measurement results in the clinical trial in order to determine physiological parameters. The velocity of the elongated magnetic probe may be determined by dividing a first induced voltage value by a second induced voltage value to obtain a relative value used to determine the velocity of the elongated magnetic probe. In some embodiments, the first velocity profile includes at least one of the velocity in the spatial domain and the velocity in the time domain. In some embodiments, the second velocity profile includes at least one of the velocity in the spatial domain and the velocity in the time domain.

[0043] This disclosure is not intended to limit the technical scope of the device to the measurement of physiological parameters of the eye. The device can be used to measure physiological parameters of any part of the body in a manner similar to that described with respect to the surface of the eyeball.

[0044] Depending on the embodiment, the device controller may be configured to perform the following: • During the movement time of the elongated magnetic probe, the second induced voltage value from sections other than the first section is measured as a function of time. The second locator value is determined as a function of time by dividing the second induced voltage value by the common induced voltage value. • Map the second locator function from the time domain to the spatial domain. • Calculate the second velocity profile of the elongated magnetic probe from the second locator value in the spatial domain. • Update the physiological parameters using the calculated second velocity profile. This update can be performed, for example, by calculating the average of the first and second velocity profiles and using that average as the velocity profile to determine the physiological parameters.

[0045] This disclosure also relates to the method described above. Various embodiments and modifications disclosed above are applicable to this method.

[0046] In some embodiments, a slender magnetic probe is directed toward the patient and bounces off a surface of the patient's body. This surface can refer to the surface of the patient's eye. By directing the probe toward the surface and measuring the velocity profile, the patient's intraocular pressure can be determined, for example. For instance, a low acceleration in the velocity profile when the probe strikes the eyeball indicates low intraocular pressure. High acceleration (i.e., a large change in the velocity profile) indicates high intraocular pressure.

[0047] In some embodiments, the measurement is performed while an elongated magnetic probe is moving, and (multiple) induced voltage values ​​are obtained as a function of time.

[0048] In some embodiments, the determination of physiological parameters is performed by analyzing the acceleration while the elongated magnetic probe is in contact with the patient's body surface, the change in velocity before and after the collision, and at least one of the depth of penetration of the elongated magnetic probe into the body surface. Since acceleration is the time derivative of velocity, it can be obtained from the velocity profile.

[0049] Depending on the embodiment, physiological parameter values ​​are updated in the following way. • Measure the induced second voltage as a function of time in a section of the measuring coil different from the first section. The second locator value is determined as a function of time by dividing the second induced voltage value by the common induced voltage value. • Map the second locator function from the time domain to the spatial domain. • From the second locator value in the spatial domain, the second velocity profile of the elongated magnetic probe is calculated as a function of position. • Update the physiological parameters using the second calculated velocity profile.

[0050] Depending on the embodiment, the first velocity profile includes at least one of the velocity in the spatial domain and the velocity in the time domain.

[0051] Depending on the embodiment, the second velocity profile includes at least one of the velocity in the spatial domain and the velocity in the time domain.

[0052] Example 1: Experimental pre-determination of transfer functions

[0053] To obtain localization, locator value mapping is performed. Here, localization refers to the value of Z and the probe velocity dZ / dt. Mathematically, the elongated magnetic probe is mapped to a linear space with position Z. Then, a robotic system is used to set and map the value of Z in order to measure a first function L with respect to Z. Here, the first function L with respect to Z is expressed as "L(Z)". Furthermore, a second function with respect to Z is determined. Here, the second function is a function that depends on the position of the elongated magnetic probe but does not depend on the signal coil induced voltage signal, the degree of magnetization of the elongated magnetic probe, or the probe velocity. The time derivative of Z is used to calculate the velocity (v) of the elongated magnetic probe.

[0054] v = dZ / dt = (dL / dt) / (dL / dZ)

[0055] For example, in the case of a long, fast-moving magnetic probe, the locator values are sampled at short time intervals. This short time interval is given by the formula T n -T n-1 where n indicates a finite time interval. The locator values are given by the formula L n -L n-1 and increase correspondingly. The velocity of the magnetic probe for the nth sample is given by the following formula.

[0056] v n = K(L n -L n-1 ) / (T n -T n-1 )

[0057] Multiple data points can be collected while making a long sweep of Z values starting from Z = 0, thereby creating multiple steps at 1 mm intervals. Here, the voltage signal is the root mean square value of the measured voltage in millivolts (mVrms) at the output of the digital oscilloscope. The range of Z that gives useful locator values is from 1 to 7, which is limited by the maximum distance tolerated by the eye being examined in order to obtain reliable results. Multiple points of data are used for fitting the localization curve, but the first 10 points of data are collected for the U+ voltage and the U- voltage respectively. The first 5 Z values are calculated from the given data. This is explained in more detail in relation to Figure 13C. And values as shown in the table of Figure 13D were observed. By removing the dependencies of the long magnetic probe on velocity, magnetization, and the first, second, third, and fourth induced voltage values, and dividing by the common induced voltage for each point, the position of the long magnetic probe is obtained. Furthermore, with the help of the measured values, an appropriate linear combination can also be created. This was explained in detail in relation to Figure 5.

[0058] Example 2: An example of how to determine the above lookup table by moving a long, thin magnetic probe back and forth.

[0059] In this disclosure, a first induced voltage, used to indicate the velocity of a magnetic probe, is induced in a measuring coil by vibrating an elongated magnetic probe using a vibrator. The vibrator uses a commercially available piezoelectric element to vibrate the elongated magnetic probe at its mechanical resonant frequency of 875 hertz (Hz). Typically, the amplitude of the vibrator's vibration is small. The vibrator is driven by setting the signal generator to 0.2 volts (V) and 0.3 V, respectively. The common induced voltage is the sum of the induced voltages of the measuring coil. The sum of the voltages of the first and second sections may be measured by measuring the induced voltages of the first and second sections separately.

[0060] In some embodiments, the common induced voltage is measured across all sections of the measuring coil, where at least the first and second sections of the measuring coil are connected to a first signal amplifier and a second signal amplifier, respectively. The first and second signal amplifiers also constitute a differential input that can be changed as needed. In an exemplary implementation, the first signal amplifier is connected between the first and third sections, and the second signal amplifier is connected between the third and fourth sections. The vibrator generates a signal of less than 1 volt (V) from the first and second signal amplifiers. This voltage is low enough to avoid saturation. Typically, the output of the drive coil is the root mean square of the measured voltage and is expressed in millivolts (mVrms). The output of a drive coil with a standard voltage of 0.2V is 500mVrms. The output of a drive coil with a standard voltage of 0.3V is 800mVrms. The inputs of the first and second signal amplifiers are connected to multiple coupling leads of the measuring coil, corresponding to approximately 1 millivolt (mV) and 1.6mV, respectively. The outputs of the first and second signal amplifiers are also connected to the inputs of a digital oscilloscope for measuring the speed of the elongated magnetic probe. The induced voltages are obtained from four sections of the measuring coil. Here, the induced voltage obtained between the first and second coupling leads is referred to as "U12", the voltage obtained between the second and third coupling leads as "U23", the voltage obtained between the third and fourth coupling leads as "U34", and the voltage obtained between the fourth and fifth coupling leads as "U45". The measurement is performed over 30 magnetization cycles by manually operating the signal generator using a drive coil of 875 Hz, 0.2 V or 0.3 V. The signal amplifier is connected to the drive coil through a third signal amplifier. A digital oscilloscope measures the root mean square values ​​of the outputs from the first and second signal amplifiers and digitally stores them in a spreadsheet. This spreadsheet has Visual Basic code to receive and display the measurements as a function of the position of an elongated magnetic probe. The position of the elongated magnetic probe is determined by integrating its velocity over time. In some embodiments, the position of the elongated magnetic probe is controlled by a robotic system. The robotic system has a linear screw driven by a stepper motor, which allows for high-precision, linear movement of the elongated magnetic probe. Moving the measuring coil at a low speed does not induce a voltage in the signal coil. The robotic system changes its position stepwise between measurements. Here, the position of the elongated magnetic probe is referred to as "Z". The mechanical end position is the starting position Z=0. The robotic system is operated to change its position by 1 millimeter (mm) for the next measurement point. This will be explained in more detail in relation to Figure 7.

[0061] In one implementation of this disclosure, the locator values ​​were observed to be linear in the range Z = 1 to 5 millimeters (mm). (Z is the distance the probe moves relative to the coil). Approximations can be obtained by fitting a trend line using a spreadsheet to points in the range Z = 1 to 5 millimeters. The resulting trend line of locator values ​​takes the form of a general linear equation y = mx + c. This trend line represents the position of the elongated magnetic probe in the range Z = 1 to 5 millimeters for measurement within the device. Here, the variables "x" and "y" are selected for further calculation. Then, in order to fit the coordinates of this disclosure, the variable x is made equivalent to Z, and the variable y is made equivalent to 1000 times the function of L(Z). Thus, the equation of the trend line is given by the following equation.

[0062] 1000L = -mZ + c

[0063] Therefore, Z can be expressed as follows:

[0064] Z = -(1000 / m)L + c / m

[0065] Here, let K = (-1000) / m be a constant. Also, let c / m be the value of Z when L = 0. That is, c / m = Z o Let's assume that V = K(dL / dt), where V is a variable. As a result, we obtain the following equation.

[0066] Z = -Vt + Z o

[0067] Thus, based on the examples and test cases, the velocity profile of the elongated magnetic probe can be determined from the locator value. This velocity profile can then be used to determine physiological parameters. In other words, the velocity of the elongated magnetic probe can be used to determine physiological parameters. In particular, the first induced voltage is proportional to the velocity of the elongated magnetic probe. [Detailed explanation of the drawing]

[0068] Referring to Figure 1, a block diagram of an apparatus 100 for determining physiological parameters according to one embodiment of the present disclosure is shown. The apparatus 100 comprises an elongated magnetic probe 102, a drive coil 104, a measuring coil 106, and a controller 108. The elongated magnetic probe 102 has a first end 102A, a second end 102B opposite to the first end 102A, and an intermediate portion 102C between the first end 102A and the second end 102B. The drive coil 104 is positioned to partially surround the elongated magnetic probe 102. The measuring coil 106 has at least a first section 106A and a second section 106B. The measuring coil 106 is positioned to partially surround the elongated magnetic probe 102. In the figure, the measuring coil has four sections, namely a first section 106A, a second section 106B, a third section 106C, and a fourth section 106D. These sections are connected in series with each other. The controller 108 is communicatively coupled to the drive coil 104 and the measuring coil 106. The controller 108 selectively energizes the drive coil 104 to generate a magnetic field, causing the elongated magnetic probe 102 to begin moving toward the eye 110. Figure 1 shows the probe at position Z=0. As an example, a first induced voltage can be measured for the first section 106A. Alternatively, a common induced voltage spanning the first section 106A and the second section 106B can be measured. Another example is that the first induced voltage can be measured over the second section 106B, and the common induced voltage can be measured as a voltage spanning, for example, all four sections. In fact, the term "first section" can refer to any section. The common induced voltage is measured from at least one or more sections different from the first section.

[0069] Referring to Figure 2, a graph is shown illustrating the relationship between the position (in millimeters) of the magnetic probe 102 and the force acting on the magnetic probe 102 (force induced per ampere of current in the signal coil or drive coil) according to an embodiment of the present disclosure. The horizontal axis represents the magnetic force acting on the magnetic probe 102 induced for a current of 1 ampere (A) flowing through the measuring coil 106 and the drive coil 104. The vertical axis represents the position of the magnetic probe 102 in millimeters. Line 202 shows the magnetic force acting on the magnetic probe 102 due to the current flowing through the measuring coil 106. Line 204 shows the magnetic force acting on the magnetic probe 102 due to the current in the drive coil 104. The upper curve 202 corresponds to a single signal coil used in the measuring instrument, and the lower curve 204 corresponds to a drive coil. The curves of the signal voltage induced by a probe moving at a constant speed within the coil look similar.

[0070] Referring to Figure 3, a graph 302 for determining the common induced voltage of the measuring coil 106 according to an embodiment of the present disclosure is shown. The common induced voltage is a function of time. At point 304, the common induced voltage increases as the drive coil 104 begins to accelerate the elongated magnetic probe 102. (The acceleration of the magnetic probe 102 starts from position Z=0mm.) The magnetic probe 102 collides with the surface of the eyeball 110 at point 306. (At this point, the position is between Z=4mm and 8mm.) The magnetic probe 102 then decelerates and becomes zero in about 1 ms. This is after 20 milliseconds (ms) to 30 ms. Then the magnetic probe 102 bounces back. These depend on the velocity of the magnetic probe 102 and the distance from the surface of the eyeball 110. Here, the change in velocity of the magnetic probe 102 while in contact with the surface of the eyeball 110 depends mainly on the velocity of the magnetic probe 102 and also on the intraocular pressure through the pushing force. The main parameter dependent on intraocular pressure is given by the slope of the deceleration of the magnetic probe 102's velocity. The deceleration of the magnetic probe 102's velocity is equal to the magnetic force between the magnetic probe 102 and the surface of the eyeball 110. The figure shows a measurement over a single section of the measuring coil. The drive coil is active when Z < 1. The probe strikes the eye when Z is approximately 5-7 mm. At this point, the driving force is close to zero.

[0071] Figure 4 shows three locator signals, with the voltage between each signal coil section measured using four differential amplifiers. The curves in the figure are created by acquiring signals from adjacent coils, i.e., the first and second sections, the second and third sections, and the third and fourth sections, drawing them in pairs, and dividing by the total U+(common induced voltage). The curves calculated in this way are all independent of probe speed and magnetization. By selecting from these curves, the probe can be localized over a wide range. It is also possible to form appropriate linear combinations to optimize the sensitivity of the selected region. In this setup, the four amplifiers / measurements need to be synchronized in order to sample each point simultaneously on all four channels. The advantage of measuring multiple first induced voltage values ​​is improved accuracy.

[0072] Referring to Figure 5, a graph for determining the position of the elongated magnetic probe 102 according to an embodiment of the present disclosure is shown. Here, the dependence of the magnetic probe 102 on velocity and magnetization is eliminated by measuring the induced voltage U13 of half a section of the measuring coil (= U12 + U23 in Figure 9) and the induced voltage U35 of the other half section (= U34 + U45). The signal ratio S is calculated as the difference between U13 and U34 divided by the common voltage Ucom of the entire coil. This signal ratio S represents the position of the elongated magnetic probe 102 and is independent of the magnetization and velocity of the probe. In Figure 5, the horizontal axis represents the position of the elongated magnetic probe 102 in millimeters. The vertical axis represents the signal ratio S, which is a function of the probe position. Using two signal points S1 and S2 at times t1 and t2, the curves give the corresponding z1 and z2. Using these signal points, the average probe velocity is calculated as vcal = (z1-z2) / (t1-t2). In this way, the probe position can be directly determined independently of the probe's magnetization, and the probe velocity can be determined indirectly.

[0073] In fact, even without knowing the magnetization coefficient of the probe, it is possible to calibrate the effect of magnetization and use that to derive the probe's position and velocity.

[0074] Referring to Figure 6, a measuring coil assembly 602 according to an embodiment of the present disclosure is shown. The measuring coil 602 is divided into a first section indicated by 602A, a second section indicated by 602B, a third section indicated by 602C, and a fourth section indicated by 602D. Furthermore, a first coupling lead 604A is connected to the left end J1 of the first section 602A, and a second coupling lead 604B is connected to the connection J2 between the first section 602A and the second section 602B. A third coupling lead 604C is connected to the connection J3 between the second section 602B and the third section 602C, a fourth coupling lead 604D is connected to the connection J4 between the third section 602C and the fourth section 602D, and a fifth coupling lead 604E is connected to the right end J5 of the fourth section 602D. The length of the measuring coil 602 may be 20 millimeters (mm). The elongated magnetic probe 610 moves linearly with an accuracy of 1 mm 612, where Z=0 is the starting position of the elongated magnetic probe 610. In this specification, the following notations are generally used: U12 represents the induced voltage between connection points J1 and J2. U16 represents the induced voltage between connection points J1 and J5 (i.e., the voltage spanning all sections 602A, 602B, 602C and 602D). U34 represents the induced voltage between connection points J3 and J4. U24 represents the induced voltage between connection points J2 and J4, i.e., the induced voltage spanning the second section 602B and the third sections 603 and C.

[0075] Referring to Figure 7, a schematic diagram of a robotic system 700 for determining the speed and position of an elongated magnetic probe 702 according to one embodiment of the present disclosure is shown. The robotic system comprises a linear screw 704 driven by a stepper motor 706. The linear screw 704 enables the elongated magnetic probe 702 to move linearly with high precision within a measuring coil 708. Furthermore, a first signal amplifier 710A and a second signal amplifier 710B are used to amplify the induced voltage of the measuring coil 708. The first signal amplifier 710A and the second signal amplifier 710B are electrically coupled to an oscilloscope 712. The elongated magnetic probe 702 is vibrated by a vibrator 714 at a frequency of 875 hertz (Hz) to determine the speed of the magnetic probe 702. The vibrator 714 is driven by a signal generator 716 via a third amplifier 718.

[0076] Referring to Figure 8, an electrical circuit 800 for adding induced voltages according to the implementation of this disclosure is shown. Multiple resistors R1, R2, R3, and R4 are shown. The first voltage input connected between the first and second sections of the measuring coil 708 is denoted as V1, the second voltage input connected to the end of the fourth section of the measuring coil 708 is denoted as V2, and the third voltage input connected between the third and fourth sections of the measuring coil 708 is denoted as V3. Firstly, the first voltage input is the negative form of the second induced voltage value, i.e., V1 = -U2. Secondly, the second voltage input is the sum of the third induced voltage value and the second induced voltage value, i.e., V2 = U3 + U4. Thirdly, the third input corresponds to the third induced voltage, and V3 = U3. Finally, the output voltage indicated by Vout is obtained. The output voltage is the sum of the first input, the second input, and the third input.

[0077] V out = V1+V2+V3 = -U2+U3+U4-U3 = U4-U2

[0078] The output voltage may be calculated for multiple resistors.

[0079] V1=(V1·R1 / (R1+R2)+V2·R1 / (R1+R2))(1+R4 / R3)-V3·R4 / R3

[0080] Referring to Figure 9, the induced signal voltage in the measuring coil 602 is shown according to the implementation of the present disclosure. The vertical axis is twice the approximate root mean square value, and the unit is millivolts. U12 shows the induced voltage obtained between the first coupling lead 604A and the second coupling lead 604B, U23 shows the voltage obtained between the second coupling lead 604B and the third coupling lead 604C, U34 shows the voltage obtained between the third coupling lead 604C and the fourth coupling lead 604D, and U45 shows the voltage obtained between the fourth coupling lead 604D and the fifth coupling lead 604E.

[0081] Referring to Figure 10, a block diagram of system 1000 for implementing a device according to an exemplary implementation of the present disclosure is shown. A first amplifier 1002 is electrically coupled to the second section 1004B and the third section 1004C of the measuring coil 1004 to measure the induced voltages of the second and third sections. The induced voltages of the second and third sections are used as a first induced voltage value. A second amplifier 1006 is electrically coupled to the first section 1004A and the fourth section 1004D of the measuring coil 1004 to determine a common induced voltage. The probe is positioned at Z=0 in the figure. The probe can be moved by the drive coil 1040.

[0082] Referring to Figures 11A and 11B, graphs are shown for achieving the optimal connection of the first amplifier 1002 and the second amplifier 1006 in Figure 10, according to the implementation of the present disclosure. As shown in Figure 10, the first amplifier 1002 is electrically coupled to the second and third sections of the measuring coil 1004. The second amplifier 1006 is electrically coupled to the first and fourth sections of the measuring coil 1004. In Figure 11A, the common induced voltage, indicated by U15, is plotted alongside the induced voltages from the second and fourth sections, indicated by U24, for a vibrator voltage of 0.2 volts (V). Also shown is the result of dividing U24 by U15 to find the optimal connection of the first amplifier 1002 and the second amplifier 1006. Figure 11B plots the common induced voltage, indicated by U15, alongside the induced voltages from the second and fourth sections, indicated by U24, for the case where the vibrator voltage is 0.3 volts. Also shown is the result of dividing U24 by U15 to find the optimal connection between the first amplifier 1002 and the second amplifier 1006.

[0083] Figure 12A shows the first measured voltage values ​​U13 and U35. Figure 12B shows the summed signal voltages (U+) representing the sum of the signal coil sections, and the difference between these signal voltages (U-). Note that U+ is equal to U15. The different notation indicates that two or more measured signals were added together for measurement. This is useful for several purposes, such as forming a difference U. A minimal system would work like this: The signal coil has two sections, each with a differential amplifier, which generates the signals shown in Figure 12A. Instead of forming the U- and U+ signals and their quotient (locator) (as in Figure 12B), a 4mm zero-crossing point can be used. If the time of this occurrence is measured, the average speed from 0 to 4mm can be calculated.

[0084] Referring to Figures 13A to 13D, graphs are shown for measuring locator values ​​by adding multiple signal amplifiers according to one embodiment of the present disclosure. In Figure 13A, line “Series 1” represents U13, which is the induced voltage in the measuring coil 602 between the first coupling lead 604A and the third coupling lead 604C. Line “Series 2” represents U35, which is the induced voltage in the measuring coil 602 between the third coupling lead 604C and the fifth coupling lead 604E. Line “Series 3” is U+, i.e., the sum of the output signals from the first signal amplifier and the second signal amplifier. U- is the difference between the output from the first signal amplifier and the output from the second signal amplifier. Figure 13B provides locator values ​​for U+ and U-. The locator signal is generated by dividing U- by U+. Figures 13A and 13B also provide data with a long sweep of Z values. Similarly, Figure 13C shows data from the range of induced voltage values, providing data for the range used to fit the trend line. Figure 13D shows the locator values ​​for U+ and U-.

[0085] Referring to Figures 14A and 14B, a flowchart is shown illustrating the steps of a method for determining physiological parameters according to one embodiment of the present disclosure. In step 1402, a drive coil is energized to move an elongated magnetic probe toward a first end of the elongated magnetic probe. In step 1404, an induced first voltage is measured as a function of time using a first section of the measuring coil. In step 1406, an induced common voltage is measured as a function of time across the measuring coil. In step 1408, a first locator value is determined as a function of time by dividing the measured induced first voltage value by the respective measured induced common voltage value. In step 1410, the first locator value is mapped from the time domain to the spatial domain. In step 1412, the first locator value in the spatial domain is used to calculate a first velocity profile of the elongated magnetic probe. In step 1414, the first velocity profile is used to determine physiological parameters.

[0086] Figure 15 is an explanatory diagram of the measured and calculated values ​​as a function of probe movement (Z-axis from 0 to 10 mm). Locator 1500 is formed by taking the ratio of the U- signal and U+ signal shown in Figure 12B. The differential curve 1510 of locator 1500 is obtained by dividing the point increment by the step length (1 mm). (Differential curve 1510 is multiplied by -4 for readability in Figure 15). The reciprocal of differential curve 1520 is the first velocity profile as a function of distance, in units of mm.

[0087] It is possible to modify the embodiments of this disclosure described above without departing from the scope defined by the attached claims. Expressions such as “includes,” “equip,” “incorporates,” “possesses,” and “is” used to describe and claim this disclosure are intended to be interpreted non-exclusively, that is, to allow for the existence of items, parts, or components not expressly described. The absence of explicit indication that an element is plural does not preclude the existence of multiple such elements.

Claims

1. A device for determining physiological parameters, An elongated magnetic probe having a first end, a second end opposite to the first end, and an intermediate portion between the first end and the second end; A drive coil is positioned so as to partially surround the magnetic probe; A measuring coil having at least a first section and a second section, and positioned to partially surround the magnetic probe; Controller and; The controller is equipped with, - To initiate movement of the magnetic probe toward the first end, the drive coil is selectively energized to generate a magnetic force; - Measuring a first induced voltage value and a common induced voltage value as a function of time while the magnetic probe is moving, wherein the first induced voltage value is the voltage across the first section, and the common induced voltage value is a voltage value spanning from the first section to the second section, or a voltage value across at least one of the second sections; - The locator value is determined as a function of time by dividing the first induced voltage value by the common induced voltage value; - Mapping the locator value from the time domain to the spatial domain as a function of time; - Calculate a first velocity profile of the magnetic probe from the spatial domain locator value, and determine physiological parameters using the calculated first velocity profile; It is configured to perform, Device.

2. During use, the first section of the measuring coil surrounds the first section of the magnetic probe, and the second section of the measuring coil surrounds the second section of the magnetic probe. The apparatus according to claim 1, wherein the first section of the magnetic probe is different from the second section of the magnetic probe.

3. The apparatus according to claim 1, wherein the mapping from the time domain to the spatial domain is performed by at least one of a predetermined transfer function or lookup table.

4. The apparatus according to claim 1, wherein the first section of the measuring coil and the second section of the measuring coil are connected in series.

5. The apparatus according to claim 1, wherein the common induced voltage value is measured across all sections of the measuring coil.

6. The aforementioned controller - During the movement time of the magnetic probe, the second induced voltage value from sections other than the first section is measured as a function of time. - By dividing the second induced voltage value by the common induced voltage value, the second locator value is determined as a function of time. - The second locator value determined above is mapped from the time domain to the spatial domain, - From the mapped second locator value, calculate the second velocity profile of the magnetic probe. - Update the physiological parameters using the calculated second velocity profile. The apparatus according to claim 1, configured as follows.

7. The apparatus according to claim 1, wherein the first velocity profile includes at least one of a velocity in the spatial domain and a velocity in the time domain.

8. The apparatus according to claim 6, wherein the second velocity profile includes at least one of a velocity in the spatial domain and a velocity in the time domain.

9. The apparatus according to any one of claims 1 to 8, which is an intraocular tonometer.

10. A method for determining physiological parameters, - To move the elongated magnetic probe toward the first end of the magnetic probe, energize the drive coil; - For the first section of the measuring coil, measure the induced first induced voltage value as a function of time; - Measure the common induced voltage value as a function of time, which is either the voltage spanning the first section and the second section of the measuring coil, or the voltage applied to the second section; - The first locator value is determined as a function of time by dividing the measured first induced voltage value by the measured common induced voltage value; - Mapping the aforementioned first locator value from the time domain to the spatial domain; - Calculate the first velocity profile of the magnetic probe from the first locator value in the spatial domain; - Determining physiological parameters using the first velocity profile; Methods that include...

11. The method according to claim 10, wherein the magnetic probe is directed toward the patient and bounces off the surface of the patient's body.

12. The method according to claim 10, wherein the measurement is performed while the magnetic probe is moving, and the induced voltage value is obtained as a function of time.

13. The method according to claim 10, wherein the determination of the physiological parameters is performed by analyzing the acceleration while the magnetic probe is in contact with the patient's body surface, by the change in velocity before and after the collision, and by the amount of penetration of the elongated magnetic probe into the body surface.

14. A method according to any one of claims 10 to 13, wherein the physiological parameter is - To measure the induced second induced voltage value as a function of time in a section of the measuring coil different from the first section; - The second locator value is determined as a function of time by dividing the second induced voltage value by the common induced voltage value; - Mapping the second locator value determined above from the time domain to the spatial domain; - Calculate the second velocity profile of the elongated magnetic probe as a function of position from the mapped second locator value; - Updating the physiological parameters using the calculated second velocity profile; The method updated by [the specified method].

15. The method according to claim 10, wherein the first velocity profile includes at least one of a velocity in the spatial domain and a velocity in the time domain.

16. The method according to claim 14, wherein the second velocity profile includes at least one of a velocity in the spatial domain and a velocity in the time domain.

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