PRESSURE SENSORS FOR SMALL-SCALE APPLICATIONS AND RELATED METHODS

• US 20140296687A1
• Filed: 10/12/2012
• Published: 10/02/2014
• Est. Priority Date: 10/12/2011
• Status: Active Grant

• Current Assignee: The Jackson Laboratory, Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: The Jackson Laboratory, Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: John, Simon W.M., Irazoqui, Pedro P., Ha, Dohyuk, Chappell, William J.
• Granted Patent: US 9,596,988 B2
• Time in Patent Office: Days
• US Class Current: 600/398
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 3/16 for measuring intraocular pressure, e.g. tonometers
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence

Abstract

Certain pressure sensor devices are much smaller than prior art devices, yet are at least as sensitive as the prior art devices. A capacitive pressure sensor can include a flexible substrate that permits bending of a pressure sensing region without significantly affecting operation thereof. The pressure sensor can include a flexible membrane in which an electrode is sandwiched between two layers of polymeric material. The sandwiched electrode can be extremely close to a reference electrode so as to provide for highly sensitive capacitance readings, yet the membrane can be restricted from contacting the reference electrode under high pressure conditions.

Claims

1-54. -54. (canceled)

55. A capacitive pressure sensor for monitoring fluid pressure within a patient, the pressure sensor comprising:

a substrate;

a first electrode in abutting contact with the substrate;

a membrane spaced from the first electrode, wherein the membrane comprises;

a second electrode configured to be displaced toward the first electrode; and

at least one flexible layer covering at least a portion of the second electrode; and

a dielectric region between the first electrode and the membrane,

wherein the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg.

56. The pressure sensor of claim 55, wherein the second electrode is thinner than the at least one flexible layer so as to readily bend when the at least one flexible layer is bent toward the substrate.

57. The pressure sensor of claim 55, wherein the second electrode is sandwiched between two flexible layers.

58. The pressure sensor of claim 55, wherein each of the substrate and the at least one flexible layer are polymeric.

59. The pressure sensor of claim 55, wherein the substrate comprises liquid crystal polymer and the at least one flexible layer comprises parylene.

60. The pressure sensor of claim 55, wherein the sensitivity is substantially constant over a range of from about 0 mmHg to about 50 mmHg above atmospheric pressure.

61. The pressure sensor of claim 55, wherein a perimeter of the substrate defines an area of no greater than about 2 millimeters².

62. The pressure sensor of claim 55, further comprising an additional flexible layer covering at least a portion of the first electrode, wherein the additional flexible layer and the at least one flexible layer of the membrane comprise the same material.

63. The pressure sensor of claim 55, wherein the dielectric region comprises a gas.

64. The capacitive pressure sensor of claim 55, wherein the membrane has a depth of no greater than about 7 microns when the membrane is in an uncompressed position.

65. The pressure sensor of claim 55, wherein the substrate is flexible so as to be able to conform to a curved surface.

66. The pressure sensor of claim 55, wherein the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg whether the substrate is in a flat orientation or a curved orientation.

67. The pressure sensor of claim 55, wherein the first electrode is configured to bend in conformity with the substrate.

68. A system for monitoring fluid pressure within an eye, the system comprising:

a substrate;

a pressure sensor coupled with the substrate;

an integrated circuit coupled with the substrate and electrically coupled with the pressure sensor;

an antenna coupled with the substrate and electrically coupled with the integrated circuit, the antenna and integrated circuit adapted to receive a first wireless signal for powering the system and transmit a second wireless signal, the second wireless signal providing an indication of the fluid pressure.

69. The system of claim 68, further comprising:

an LED coupled with the substrate and electrically coupled with the integrated circuit, wherein a maximum width of the LED is not greater than the maximum width of the substrate, wherein the light intensity of the LED output provides an indication of power being received by the system from a wireless external power source.

70. The system of claim 68, wherein the antenna transmits the second signal at a harmonic of the frequency of the first signal.

71. The system of claim 68, wherein the harmonic is the third harmonic of the first signal.

72. The system of claim 68, wherein the substrate defines a maximum width of no greater than about 0.7 millimeters;

wherein a maximum width of the pressure sensor is no greater than the maximum width of the substrate; and

wherein a maximum width of the integrated circuit is no greater than the maximum width of the substrate.

73. A non-human animal having implanted therein a pressure sensor according to claim 68.

74. The non-human animal of claim 73, wherein the pressure sensor is implanted in the eye of the animal.