# US 12,120,959 B2 · Stacked piezoelectric energy harvester > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,120,959 B2 - Document ID: US12120959B2 - Status: Granted - Kind: B2 - Application number: 17/045,262 - Filed: 2019-04-02 - Published: 2021-11-25 - Granted: 2024-10-15 - Earliest claimed: 2018-04-06 - Assignees: University of Kansas; Evoke Medical, LLC - Applicants: University of Kansas; Evoke Medical, LLC - Inventors: Elizabeth Annamaria Friis; Ember Krech; Eileen Cadel; Bonnie Reinsch; Leighton Lapierre - Web page: https://patentgrep.com/patent/US12120959B2 ## CPC - H02N 2/186: {Vibration harvesters} - H10N 30/50: having a stacked or multilayer structure - H10N 30/30: with mechanical input and electrical output, e.g. functioning as generators or sensors - H10N 30/8536: {Alkaline earth metal based oxides, e.g. barium titanates} - H10N 30/8554: {Lead-zirconium titanate [PZT] based} - H10N 30/857: Macromolecular compositions - A61N 1/0551: {Spinal or peripheral nerve electrodes} - H02N: ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - 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) ## Abstract The present application relates to stacked piezoelectric energy harvesters that include compliant layers between piezoelectric layers. The energy harvesters are useful in various structures and devices, including tissue-stimulating implants, such as spinal fusion implants. The present application also relates to methods of increasing the power output of a piezoelectric energy harvester through the inclusion of compliant layers. ## Claims ### Claim 1 A stacked piezoelectric energy harvester, comprising: a. a first piezoelectric element layer; b. a first compliant layer positioned adjacent the first piezoelectric element layer; and c. a second piezoelectric element layer positioned adjacent the first compliant layer, wherein a ratio of a volume of the first piezoelectric element layer and/or a volume of the second piezoelectric element layer, to a volume of the first compliant layer is between about 1:8 volume piezoelectric:volume compliant to about 8:1 volume piezoelectric:volume compliant, or wherein a ratio of a thickness of the first piezoelectric element layer and/or a thickness of the second piezoelectric element layer, to a thickness of the first compliant layer is between about 1:8 thickness piezoelectric:thickness compliant to about 8:1 thickness piezoelectric:thickness compliant; and wherein the first piezoelectric element layer is poled in a radial direction and the second piezoelectric element layer is poled in a through-thickness direction; and, wherein the stacked energy harvester is configured to withstand a minimum load of at least 500 N. ### Claim 2 (depends on 1) The stacked piezoelectric energy harvester of claim 1, wherein the first piezoelectric element layer comprises lead zirconium titanate, barium titanate or polyvinylidene difluoride (PVDF). ### Claim 3 (depends on 1) The stacked piezoelectric energy harvester of claim 1, wherein the first compliant layer comprises a polymer. ### Claim 4 (depends on 3) The stacked piezoelectric energy harvester of claim 3, wherein the polymer is an epoxy, a polyethylene, or a polyether ether ketone (PEEK). ### Claim 5 (depends on 1) The stacked piezoelectric energy harvester of claim 1, wherein the first compliant layer has a bulk modulus that is at least 50% less than a bulk modulus of the first piezoelectric element layer and/or the second piezoelectric element layer. ### Claim 6 (depends on 1) The stacked piezoelectric energy harvester of claim 1, further comprising a polymer encapsulating the stacked piezoelectric energy harvester. ### Claim 7 (depends on 1) The stacked piezoelectric energy harvester of claim 1, wherein the ratio of the volume of the first piezoelectric element layer and/or the volume of the second piezoelectric element layer, to the volume of the first compliant layer is between about 1:4 volume piezoelectric:volume compliant to about 1:8 volume piezoelectric:volume compliant. ### Claim 8 (depends on 1) The stacked piezoelectric energy harvester of claim 1, wherein the first compliant layer has a thickness of about 0.2 mm to about 8 mm. ### Claim 9 (depends on 1) The stacked piezoelectric energy harvester of claim 1, further comprising one or more additional piezoelectric element layers and one or more additional compliant layers. ### Claim 10 (depends on 9) The stacked piezoelectric energy harvester of claim 9, wherein each of the compliant layers has a thickness within about 40% of each other. ### Claim 11 (depends on 9) The stacked piezoelectric energy harvester of claim 9, wherein each of the compliant layers has a thickness within about 10% of each other. ### Claim 12 (depends on 1) A method of providing power generation from the stacked piezoelectric energy harvester of claim 1, comprising loading the stacked piezoelectric energy harvester with a load of at least about 500 N. ### Claim 13 (depends on 12) The method of claim 12, wherein the power generation is provided to a tissue-stimulating implant of a patient. ### Claim 14 (depends on 13) The method of claim 13, wherein the tissue-stimulating implant is a spinal implant. ### Claim 15 A stacked piezoelectric energy harvester, comprising: alternating layers of: N compliant layers; and N−1 piezoelectric element layers; wherein the compliant layers and the piezoelectric element layers are adjacent one another, wherein N is a whole integer between 3 and 20, and wherein a ratio of a volume of at least one of the piezoelectric element layers, to a volume of at least one of the compliant layers is between about 1:8 volume piezoelectric:volume compliant to about 8:1 volume piezoelectric:volume compliant, or wherein a ratio of a thickness of at least one of the piezoelectric element layers, to a thickness of at least one of the compliant layers is between about 1:8 thickness piezoelectric:thickness compliant to about 8:1 thickness piezoelectric:thickness compliant; and wherein the stacked piezoelectric energy harvester has a total thickness in the range of 11 mm to 17 mm. ### Claim 16 (depends on 15) The stacked piezoelectric energy harvester of claim 15, wherein the piezoelectric element layers are electrically connected to each other. ### Claim 17 (depends on 15) The stacked piezoelectric energy harvester of claim 15, wherein the piezoelectric element layers comprise lead zirconium titanate, barium titanate or polyvinylidene difluoride (PVDF). ### Claim 18 (depends on 15) The stacked piezoelectric energy harvester of claim 15, wherein the compliant layers comprise a polymer. ### Claim 19 (depends on 18) The stacked piezoelectric energy harvester of claim 18, wherein the polymer is an epoxy, a polyethylene, or a polyether ether ketone (PEEK). ### Claim 20 (depends on 15) The stacked piezoelectric energy harvester of claim 15, wherein each of the compliant layers has a bulk modulus that is at least 50% less than a bulk modulus of each of the piezoelectric element layers.