# US 2013/0278111 A1 · Piezoelectric micromachined ultrasound transducer with patterned electrodes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278111 A1 - Document ID: US20130278111A1 - Status: Published application - Kind: A1 - Application number: 13/833,159 - Filed: 2013-03-15 - Published: 2013-10-24 - Earliest claimed: 2012-04-19 - Assignees: Masdar Institute of Science and Technology; Massachusetts Institute of Technology - Applicants: Masdar Institute of Science and Technology; Massachusetts Institute of Technology - Inventors: Firas Sammoura; Katherine Marie Smyth; Sang-Gook Kim - Web page: https://patentgrep.com/patent/US20130278111A1 ## CPC - H10N 30/87: Electrodes or interconnections, e.g. leads or terminals - B06B 1/0622: {on one surface} - H10N 30/20: with electrical input and mechanical output, e.g. functioning as actuators or vibrators - H10N 30/204: {using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders} - B06B 1/0625: {Annular array} - B06B 1/0629: {Square array} - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R) ## Abstract A piezoelectric micro-machined ultrasonic transducer (PMUT) uses multiple electrodes, e.g., in a radial pattern for a disc, to improve performance. The multiple electrodes may be differentially driven to operate the PMUT in d31 mode (that is, with an applied electrical field perpendicular to the piezoelectrically-induced strain) where deflection relative to input voltage is increased and in-plane stresses are reduce, thus improving overall performance. ## Claims ### Claim 1 A device formed of a clamped, micromachined structure, the device comprising: a piezoelectric material having a top surface and a bottom surface; a first group of electrodes forming a pattern on the top surface of the first piezoelectric material; and a second group of electrodes forming the pattern on the bottom surface of the first piezoelectric material. ### Claim 2 (depends on 1) The device of claim 1 wherein the piezoelectric material is a disc. ### Claim 3 (depends on 2) The device of claim 2 wherein the first group of electrodes includes a first electrode having a circular shape centered on the disc. ### Claim 4 (depends on 1) The device of claim 1 wherein the piezoelectric material has a perimeter shape selected from a group consisting of a square and a hexagon. ### Claim 5 (depends on 1) The device of claim 1 wherein the first group of electrodes forms a number of concentric rings separated by a corresponding number of gaps. ### Claim 6 (depends on 1) The device of claim 1 wherein the first group of electrodes includes three or more electrodes. ### Claim 7 (depends on 6) The device of claim 6 further comprising a voltage source configured to drive each one of the three or more electrodes at a substantially different voltage. ### Claim 8 (depends on 6) The device of claim 6 further comprising a voltage source that drives at least two of the three or more electrodes at a substantially equal voltage. ### Claim 9 (depends on 8) The device of claim 8 wherein the substantially equal voltage is about zero Volts. ### Claim 10 (depends on 1) The device of claim 1 further comprising a voltage source configured to differentially drive adjacent ones of the first group of electrodes. ### Claim 11 (depends on 1) The device of claim 1 further comprising a voltage source configured to differentially drive one of the first group of electrodes and an opposing one of the second group of electrodes. ### Claim 12 (depends on 1) The device of claim 1 wherein the piezoelectric material is not initially poled. ### Claim 13 (depends on 1) The device of claim 1 wherein the piezoelectric material is poled Aluminum nitride. ### Claim 14 (depends on 1) The device of claim 1 further comprising a silicon substrate. ### Claim 15 (depends on 1) The device of claim 1 wherein the clamped, micromachined structure includes a support structure. ### Claim 16 (depends on 1) The device of claim 1 wherein the piezoelectric material includes a Lead Zirconate Titanate (PZT). ### Claim 17 (depends on 1) The device of claim 1 wherein the PZT is Perovskite-phase PZT. ### Claim 18 (depends on 1) The device of claim 1 wherein the piezoelectric material includes a piezoelectric ceramic bulk material. ### Claim 19 (depends on 1) The device of claim 1 wherein the clamped, micromachined structure is an ultrasound transducer having a resonant frequency of between one and eighteen Megahertz. ### Claim 20 (depends on 1) The device of claim 1 wherein the first group of electrodes covers about thirty-six percent of a top area of the piezoelectric material. ### Claim 21 (depends on 1) The device of claim 1 wherein the first group of electrodes cover about sixty percent of a radius of the piezoelectric material. ### Claim 22 (depends on 1) The device of claim 1 further comprising: a second piezoelectric material having a second top surface and a second bottom surface, the second top surface adjacent to the second group of electrodes; and a third group of electrodes forming the pattern on the second bottom surface of the second piezoelectric material. ### Claim 23 (depends on 22) The device of claim 22 further comprising a voltage source that drives one of the third group of electrodes and a corresponding one of the first group of electrodes at a substantially equal voltage.