# US 7,610,089 B1 · Implantable strain sensor for medical diagnostics > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,610,089 B1 - Document ID: US7610089B1 - Status: Granted - Kind: B1 - Application number: 11/677,536 - Filed: 2007-02-21 - Granted: 2009-10-27 - Earliest claimed: 2007-02-21 - Assignees: Pacesetter, Inc. - Inventors: Rodolfo Rodriguez; Annapurna Karicherla - Web page: https://patentgrep.com/patent/US7610089B1 ## CPC - A61N 1/36514: {controlled by a physiological quantity other than heart potential, e.g. blood pressure (controlled by two or more physical parameters A61N1/36585)} - A61B 5/1107: {Measuring contraction of parts of the body, e.g. organ or muscle} - H10N 30/302: {Sensors} - H10N 30/503: {having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view} - H10N 30/802: {Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits} - H10N 30/875: {Further connection or lead arrangements, e.g. flexible wiring boards, terminal pins} - H10N 30/883: {Additional insulation means preventing electrical, physical or chemical damage, e.g. protective coatings} - A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)} - A61B 2562/0261: Strain gauges - A61N 1/36578: {controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone} - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract Embodiments include strain sensor devices for detecting movement, morphological changes or other physical parameters within a patient's body tissue. Some embodiments are directed specifically to measuring parameters within a patient's heart and may also be configured to communicate with an implantable stimulation device and associated external programming device. ## Claims ### Claim 1 A piezoelectric strain sensor for use within a patient's body, comprising: a first resilient shear layer; a second resilient shear layer disposed apart from and substantially parallel to the first resilient shear layer; a piezoelectric element disposed between the first resilient shear layer and the second resilient shear layer with the first resilient shear layer and second resilient shear layer configured to apply shear strain onto the piezoelectric element upon bending of the first resilient shear layer and second resilient shear layer; and a compliant filler material disposed between the first resilient shear layer and second resilient shear layer. ### Claim 2 (depends on 1) The strain sensor of claim 1 further comprising a hermetic seal coating disposed over external exposed portions of the strain sensor. ### Claim 3 (depends on 2) The strain sensor of claim 2 wherein the hermetic seal coating comprises a layer of dielectric material and a metallic layer outside the dielectric material. ### Claim 4 (depends on 3) The strain sensor of claim 3 wherein the dielectric material comprises a conformal pin-hole free parylene coating. ### Claim 5 (depends on 3) The strain sensor of claim 3 wherein the metallic layer comprises a thin layer of noble metal. ### Claim 6 (depends on 1) The strain sensor of claim 1 wherein the piezoelectric element comprises a first side secured to the first resilient shear layer, a second side opposite the first side and secured to the second resilient shear layer, a thickness dimension between the first side and the second side, a major transverse dimension that is substantially greater than the thickness dimension and a polarization direction extending from the second side to the first side of the piezoelectric element in an orientation that is substantially perpendicular to the second side of the piezoelectric element. ### Claim 7 (depends on 6) The strain sensor of claim 6, wherein the piezoelectric element is configured such that a d51 piezoelectric coefficient is activated in the piezoelectric element by shear force applied by the first resilient shear layer and second resilient shear layer. ### Claim 8 (depends on 1) The strain sensor of claim 1 further comprising a second piezoelectric element disposed between and secured to the first resilient shear layer and second resilient shear layer with the first resilient shear layer and second resilient shear layer configured to apply shear strain onto the second piezoelectric element upon bending of the first resilient shear layer and second resilient shear layer. ### Claim 9 (depends on 8) The strain sensor of claim 8 wherein the compliant filler material is disposed between the first resilient shear layer and second resilient shear layer around the first and second piezoelectric elements. ### Claim 10 (depends on 8) The strain sensor of claim 8 wherein the piezoelectric elements are disposed on opposite sides of a longitudinal center line of the first resilient shear layer and a longitudinal center line of the second resilient shear layer. ### Claim 11 (depends on 1) The strain sensor of claim 1 wherein at least one of the first resilient shear layer and the second resilient shear layer comprises a superelastic material. ### Claim 12 (depends on 11) The strain sensor of claim 11 wherein the superelastic material comprises NiTi alloy. ### Claim 13 (depends on 1) The strain sensor of claim 1 wherein the piezoelectric element is disposed laterally away from a longitudinal center line of the first resilient shear layer and a longitudinal center line of the second resilient shear layer. ### Claim 14 (depends on 1) The strain sensor of claim 1 wherein the first resilient shear layer and second resilient shear layer have substantially the same shape and size in the transverse dimensions and have outer edges which are aligned. ### Claim 15 A piezoelectric strain sensor for use within a patient's body, comprising: a first resilient shear layer; a second resilient shear layer disposed apart from and substantially parallel to the first resilient shear layer; a first piezoelectric element disposed transversely away from a longitudinal center line of the first resilient shear layer and a longitudinal center line of the second resilient shear layer and having a first side secured to the first resilient shear layer, a second side opposite the first side and secured to the second resilient shear layer, a thickness dimension between the first side and the second side, a major transverse dimension that is substantially greater than the thickness dimension, a polarization direction extending from the second side to the first side of the first piezoelectric element in an orientation that is substantially perpendicular to the second side of the first piezoelectric element; a second piezoelectric element disposed transversely on an opposite side of the longitudinal center line of the first resilient shear layer from the first piezoelectric element and having a first side secured to the first resilient shear layer, a second side opposite the first side and secured to the second resilient shear layer, a thickness dimension between the first side and the second side, a major transverse dimension that is substantially greater than the thickness dimension, a polarization direction extending from the first side to the second side of the second piezoelectric element in an orientation that is substantially perpendicular to the first side of the second piezoelectric element; and a compliant filler material disposed between the first resilient shear layer and second resilient shear layer. ### Claim 16 (depends on 15) The strain sensor of claim 15 further comprising: a third resilient shear layer disposed apart from and substantially parallel to the second resilient shear layer; a third piezoelectric element disposed transversely away from a longitudinal center line of the second resilient shear layer and a longitudinal center line of the third resilient shear layer and having a first side secured to the second resilient shear layer, a second side opposite the first side and secured to the third resilient shear layer, a thickness dimension between the first side and the second side, a major transverse dimension that is substantially greater than the thickness dimension, a polarization direction extending from the second side to the first side of the third piezoelectric element in an orientation that is substantially perpendicular to the second side of the third piezoelectric element; a fourth piezoelectric element disposed transversely on an opposite side of the longitudinal center line of the second resilient shear layer from the third piezoelectric element and having a first side secured to the second resilient shear layer, a second side opposite the first side and secured to the third resilient shear layer, a thickness dimension between the first side and the second side, a major transverse dimension that is substantially greater than the thickness dimension, a polarization direction extending from the first side to the second side of the fourth piezoelectric element in an orientation that is substantially perpendicular to the first side of the fourth piezoelectric element; and a compliant filler material disposed between the first resilient shear layer and second resilient shear layer. ### Claim 17 (depends on 16) The strain sensor claim 16 wherein the first piezoelectric element and third piezoelectric element are substantially aligned in transverse directions in a stacked configuration. ### Claim 18 (depends on 17) The strain sensor of claim 17 wherein the second piezoelectric element and fourth piezoelectric element are substantially aligned in transverse directions in a stacked configuration. ### Claim 19 (depends on 15) The strain sensor of claim 15 wherein the piezoelectric elements are configured such that a d51 piezoelectric coefficient is activated in the piezoelectric elements by shear force applied by the respective resilient shear layers. ### Claim 20 (depends on 15) The strain sensor of claim 15 further comprising a first electrical conductor in electrical communication with the first side of the piezoelectric elements and a second electrical conductor in electrical communication with the second side of the piezoelectric elements. ### Claim 21 An implantable piezoelectric strain sensor comprising a hermetic seal coating having a dielectric layer and a thin noble metal layer disposed outside of the dielectric layer. ### Claim 22 (depends on 21) The strain sensor of claim 21 wherein the dielectric material comprises a conformal pin-hole free parylene coating. ### Claim 23 (depends on 21) The strain sensor of claim 21 wherein the thin metallic layer has a thickness of about 0.5 micron to about 2 microns. ### Claim 24 (depends on 21) The strain sensor of claim 21 wherein the a material of the thin metallic layer is selected from platinum or titanium. ### Claim 25 A tissue stimulation system comprising: an implantable stimulation device; and a strain sensor in communication with the implantable stimulation device, the strain sensor including: a first resilient shear layer; a second resilient shear layer disposed apart from and substantially parallel to the first resilient shear layer; a piezoelectric element disposed between the first resilient shear layer and the second resilient shear layer with the first resilient shear layer and second resilient shear layer configured to apply shear strain onto the piezoelectric element upon bending of the first resilient shear layer and second resilient shear layer; and a compliant filler material disposed between the first resilient shear layer and second resilient shear layer. ### Claim 26 (depends on 25) The system of claim 25 wherein the strain sensor is in electrical communication with the implantable stimulation device. ### Claim 27 (depends on 25) The system of claim 25 further comprising a lead in electrical communication with the implantable stimulation device, wherein the strain sensor is disposed within or on a body portion of the lead.