Patents by Inventor Robert J. Littrell

Robert J. Littrell has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 9853201
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Grant
    Filed: August 5, 2014
    Date of Patent: December 26, 2017
    Assignee: The Regents of the University of Michigan
    Inventors: Karl Grosh, Robert J. Littrell
  • Publication number: 20170150248
    Abstract: A package comprises: a transducer; a substrate comprising an acoustic port, with the transducer attached to a surface of the substrate and over or adjacent to the acoustic port; and a venting mechanism for venting air or sound pressure from a device comprising the package, with the venting mechanism being affixed to the substrate and partially surrounding the acoustic port, and with the venting mechanism being dimensioned to filter out audio frequencies.
    Type: Application
    Filed: November 21, 2016
    Publication date: May 25, 2017
    Inventor: Robert J. Littrell
  • Publication number: 20150350792
    Abstract: A microphone including a casing having a front wall, a back wall, and a side wall joining the front wall to the back wall, a transducer mounted to the front wall, the transducer including a substrate and a transducing element, the transducing element having a transducer acoustic compliance dependent on the transducing element dimensions, a back cavity cooperatively defined between the back wall, the side wall, and the transducer, the back cavity having a back cavity acoustic compliance. The transducing element is dimensioned such that the transducing element length matches a predetermined resonant frequency and the transducing element width, thickness, and elasticity produces a transducer acoustic compliance within a given range of the back cavity acoustic compliance.
    Type: Application
    Filed: March 13, 2014
    Publication date: December 3, 2015
    Inventors: Karl Grosh, Robert J. Littrell
  • Publication number: 20150271606
    Abstract: A transducer of the preferred embodiment including a transducer and a plurality of adjacent, tapered cantilevered beams. Each of the beams define a beam base, a beam tip, and a beam body disposed between the beam base and the beam tip. The beams are arranged such that each of the beam tips extends toward a common area. Each beam is joined to the substrate along the beam base and is free from the substrate along the beam body. A preferred method of manufacturing a transducer can include: depositing alternating layers of piezoelectric and electrode onto the substrate in block, processing the deposited layers to define cantilever geometry in block, depositing metal traces in block, and releasing the cantilevered beams from the substrate in block.
    Type: Application
    Filed: May 1, 2015
    Publication date: September 24, 2015
    Inventors: Karl Grosh, Robert J. Littrell
  • Patent number: 8896184
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Grant
    Filed: August 9, 2013
    Date of Patent: November 25, 2014
    Assignee: The Regents of The University of Michigan
    Inventors: Karl Grosh, Robert J. Littrell
  • Publication number: 20140339657
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Application
    Filed: August 5, 2014
    Publication date: November 20, 2014
    Inventors: Karl Grosh, Robert J. Littrell
  • Publication number: 20130329920
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Application
    Filed: August 9, 2013
    Publication date: December 12, 2013
    Applicant: The Regents of the University of Michigan
    Inventors: Karl Grosh, Robert J. Littrell
  • Patent number: 8531088
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Grant
    Filed: June 30, 2009
    Date of Patent: September 10, 2013
    Assignee: The Regents of The University of Michigan
    Inventors: Karl Grosh, Robert J. Littrell
  • Publication number: 20100254547
    Abstract: A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
    Type: Application
    Filed: June 30, 2009
    Publication date: October 7, 2010
    Applicant: THE REGENTS OF THE UNIVERSITY OF MICHIGAN
    Inventors: Karl Grosh, Robert J. Littrell