# US 12,007,291 B2 · Pressure sensing unit, system and method for remote pressure sensing

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- Number: US 12,007,291 B2
- Document ID: US12007291B2
- Status: Granted
- Kind: B2
- Application number: 17/250,141
- Filed: 2019-06-11
- Published: 2021-08-12
- Granted: 2024-06-11
- Earliest claimed: 2018-06-20
- Assignees: Koninklijke Philips N.V.
- Applicants: Koninklijke Philips N.V.
- Inventors: Bernhard Gleich; Jürgen Erwin Rahmer
- Web page: https://patentgrep.com/patent/US12007291B2

## CPC

- G01K 7/36: using magnetic elements, e.g. magnets, coils (magnetic elements per se H01F)
- A61B 1/00158: {using magnetic field}
- A61B 5/0215: by means inserted into the body
- A61B 5/02152: {specially adapted for venous pressure}
- A61B 5/03: Measuring fluid pressure within the body other than blood pressure, e.g. cerebral pressure {; Measuring pressure in body tissues or organs (determining bladder or urethral pressure A61B5/205)}
- A61B 5/05: Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24)
- A61B 5/062: {using magnetic field}
- A61B 5/6847: {mounted on an invasive device}
- A61B 5/6851: {Guide wires}
- A61B 5/6852: {Catheters}
- A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
- A61B 90/36: {Image-producing devices or illumination devices not otherwise provided for}
- A61B 90/39: {Markers, e.g. radio-opaque or breast lesions markers}
- A61M 25/0127: {Magnetic means; Magnetic markers}
- G01K 1/26: Compensating for effects of pressure changes
- G01K 13/04: for measuring temperature of moving solid bodies
- G01L 1/10: by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings (using resistance strain gauges G01L1/22)
- G01L 9/0001: {Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means (G01L9/0026, G01L9/0033, G01L9/0082, G01L9/0089, G01L9/0091 take precedence)}
- G01L 9/007: {using variations in inductance}
- G01L 19/14: Housings {(G01L19/0007, G01L19/0084, G01L19/0092, G01L19/04, G01L19/06 take precedence)}
- A61B 5/02158: {provided with two or more sensor elements}
- A61B 5/6853: {with a balloon}
- A61B 5/6862: {Stents}
- A61B 2017/00809: {Lung operations}
- A61B 2034/2051: {Electromagnetic tracking systems}
- A61B 2034/2072: {Reference field transducer attached to an instrument or patient}
- A61B 2090/309: {using white LEDs}
- A61B 2090/376: {using X-rays, e.g. fluoroscopy}
- A61B 2090/3937: {Visible markers}
- A61B 2090/3954: {magnetic, e.g. NMR or MRI}
- A61B 2090/3958: {emitting a signal}
- A61B 2090/3966: {Radiopaque markers visible in an X-ray image}
- A61B 2090/3995: {Multi-modality markers}
- A61B 2560/0252: using ambient temperature
- A61B 2562/0223: Magnetic field sensors
- A61M 25/09041: {Mechanisms for insertion of guide wires}
- A61M 2025/0166: {Sensors, electrodes or the like for guiding the catheter to a target zone, e.g. image guided or magnetically guided}
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

A wireless pressure sensing unit (20) comprises a membrane (25) forming an outer wall portion of a cavity and two permanent magnets (26,28) inside the cavity. One magnet is coupled to the membrane, and at least one magnet is free to oscillate with a rotational movement. At least one is free to oscillate with a rotational movement. The oscillation takes place at a resonance frequency, which is a function of the sensed pressure, which pressure influences the spacing between the two permanent magnets. This oscillation frequency can be sensed remotely by measuring a magnetic field altered by the oscillation. The wireless pressure sensing unit may be provided on a catheter (21) or guidewire.

## Claims

### Claim 1

A pressure sensing unit, comprising:
a structure defining a closed cavity, wherein the structure comprises at least one membrane forming an outer wall portion of the closed cavity, and wherein the structure is configured to be implanted within a human subject;
a first permanent magnet inside the closed cavity and coupled to the at least one membrane; and
a second permanent magnet inside the closed cavity,
wherein the second permanent magnet is coupled to the structure by a fixed coupling, wherein the fixed coupling prevents rotational movement of the second permanent magnet with respect to the structure; and
an elongate structure,
wherein the first permanent magnet is coupled to the at least one membrane by the elongate structure, wherein the elongate structure allows rotational movement of the first permanent magnet with respect to the structure.

### Claim 2 (depends on 1)

The unit as claimed in claim 1, wherein the elongate structure comprises a wire or thread.

### Claim 3 (depends on 1)

The unit as claimed in claim 1, wherein the membrane is made from an elastomer or a patterned metal sheet.

### Claim 4 (depends on 1)

The unit as claimed in claim 1, wherein the structure has a shape of a cylinder, and;
wherein there is one membrane which forms one end of the cylinder; or
there is a respective membrane forming each end of the cylinder.

### Claim 5 (depends on 4)

The unit as claimed in claim 4, wherein the first permanent magnet has a rotationally symmetric shape.

### Claim 6 (depends on 1)

The unit as claimed in claim 1, wherein an interior of the closed cavity, except for the first and second permanent magnets and the elongate structure is filled with air or holds a vacuum.

### Claim 7 (depends on 1)

The unit as claimed in claim 1, wherein the unit has an outer diameter of no more than 0.3 mm.

### Claim 8 (depends on 1)

A pressure sensing system, comprising:
a pressure sensing unit of claim 1;
an excitation coil arrangement having a plurality of coils for wirelessly inducing a resonant rotational oscillation of said first permanent magnet by generating a magnetic field.

### Claim 9 (depends on 8)

A system as claimed in claim 8, further comprising a controller, wherein the controller is adapted to:
control the excitation coil arrangement to induce and sustain resonant oscillation of the said first permanent magnet; and
measure a magnetic field which is altered by the resonant oscillation.

### Claim 10 (depends on 9)

The system as claimed in claim 9, wherein the controller is adapted to control the excitation coil arrangement to induce and sustain the resonant oscillation by applying a discontinuous external magnetic field.

### Claim 11 (depends on 10)

The system as claimed in claim 10, wherein the controller is adapted to measure a magnetic field between active periods of the discontinuous external field.

### Claim 12 (depends on 8)

The system as claimed in claim 8, wherein the controller is adapted to use a same coil or ones of the cods for inducing and sustaining the resonant oscillation as for measuring the magnetic field.

### Claim 13 (depends on 8)

The system as claimed in claim 8, comprising multiple pressuring sensing units, each with different resonant frequencies.

### Claim 14 (depends on 8)

A catheter or guidewire system, comprising:
a catheter or guidewire; and
a system as claimed in claim 8, wherein the pressure sensor unit is provided along the catheter or guidewire.

### Claim 15

A pressure sensing method, comprising:
using an excitation coil arrangement to wirelessly excite a pressure sensing unit into a resonant oscillation, wherein the pressure sensing unit is implanted into a human subject and comprises:
a structure defining a dosed cavity, wherein the structure comprises at least one membrane forming an outer wall portion of the dosed cavity;
a first permanent magnet inside the dosed cavity and coupled to the at least one membrane;
a second permanent magnet inside the dosed cavity, wherein the second permanent magnet is coupled to the structure by a fixed coupling, wherein the fixed coupling prevents rotational movement of the second permanent magnet with respect to the structure, and wherein the first permanent magnet is coupled to the membrane by an elongate structure, wherein the elongate structure allows rotational movement of the first permanent magnet with respect to the structure, wherein at least a part of magnetic moment between the first and second permanent magnets is oriented perpendicular to a rotation axis of the first permanent magnet, wherein the first permanent magnet is excited into the resonant oscillation;
measure a magnetic field which is altered by the resonant oscillation; and
determine a pressure from the frequency of alteration of the measured magnetic field.

### Claim 16 (depends on 1)

The unit of claim 1, wherein the elongate structure is only supported by the first permanent magnet and the membrane which forms the outer wall portion of the closed cavity.

### Claim 17 (depends on 1)

The unit of claim 1, wherein the elongate structure extends between a first end thereof and a second end thereof, wherein the elongate structure further extends between the first permanent magnet and the membrane which forms the outer wall portion of the closed cavity, and wherein the elongate structure is connected at the first end thereof to the first permanent magnet, and wherein elongate structure is connected at the second end thereof to the membrane which forms the outer wall portion of the closed cavity.

### Claim 18 (depends on 8)

The pressure sensing system of claim 8, wherein in the pressure sensing unit, the elongate structure is only supported by the first permanent magnet and the membrane which forms the outer wall portion of the closed cavity.

### Claim 19 (depends on 15)

The method of claim 15, wherein the elongate structure is only supported by the first permanent magnet and the membrane which forms the outer wall portion of the closed cavity.

### Claim 20 (depends on 15)

The method of claim 15, wherein the elongate structure extends between a first end thereof and a second end thereof, wherein the elongate structure further extends between the first permanent magnet and the membrane which forms the outer wall portion of the dosed cavity, and wherein the elongate structure is connected at the first end thereof to the first permanent magnet, and wherein elongate structure is connected at the second end thereof to the membrane which forms the outer wall portion of the dosed cavity.