Capacitive Transducers with Curved Electrodes

Robert B. McIntosh
Founder, Horizon Technology Group, Inc
IEEE Senior Member

Robert McIntosh

Thursday, March 16, 2006 at 6:30 PM

Location: Aberdeen Barn
5805 Northampton Blvd
Virginia Beach, VA 23455
(757) 464-1580
(757) 464-6905 (fax)

Presentation Summary: Mr. McIntosh will highlight innovative portions of his January 2006, IEEE Sensor Journal paper: “Capacitive Transducers with Curved Electrodes” of particular interest to student members. He will also discuss approaches to R&D that illustrate both successes and failures, and what he believes are fundamental rules of success for new engineers and managers.
After the presentation, McIntosh will be available to talk with members having specific interest and experience in sensing technologies. His recent paper shows that the sensitivity and dynamic range of capacitive sensors and actuators with curved electrodes are higher and wider than devices with parallel electrodes. An electrical advantage is obtained from the permittivity of a fixed dielectric film and a mechanical advantage from its thinness. Transducers were constructed with silicon diaphragms that bend and polymer membranes that stretch in response to applied stress. Ocean bottom sensors with silicon diaphragms can measure dynamic pressure changes over a linear range of 125 dB. An 885% change in capacitance was obtained for a sensor in air with a thin diaphragm. By comparison, electrostatic collapse limits the capacitance change of conventional devices with parallel-plate electrodes to about 20%.
Sensors with polycarbonate membranes demonstrated the ability of a low-cost transducer to measure pressure, fluid flow, displacement, and tilt. Arrays of micromachined capacitors are ideally suited for sonar and ultrasonic imaging applications. An active capacitive bridge circuit was developed to linearly measure capacitance changes up to 1000% and to control electrostatic actuators by force-balanced feedback.

Biographical Sketch: A Sr. Member of IEEE since 1988, Robert B. McIntosh, received a BSEE from the University of Pennsylvania (1961) and an MSEE from New York University (1962). Early in his career, McIntosh was the Program Manager for the Apollo 17, Infrared Scanning Radiometer that thermally mapped the dark side of the moon from lunar orbit. Later, he was employed at the Optical and Microlithography Groups of Perkin-Elmer Corp, Norwalk, CT.
Mr. McIntosh founded Horizon Technology Group, Inc. in 1986 and moved the company to Washington, DC. From 1986 to 1989, HTG provided proposal and strategic planning assistance to government agencies, companies, and research universities. Since 1989, HTG has performed R&D and SBIR contracts for the Navy, Air Force, DARPA, BMDO, and USDA for advanced sensing and semiconductor manufacturing technology. McIntosh was president of HTG until his retirement in 2004. He has 12 patents which he prosecuted pro se for capacitive sensors and sensor manufacturing methods. A Sr. Member of IEEE since 1988, Robert B. McIntosh, received a BSEE from the University of Pennsylvania (1961) and an MSEE from New York University (1962). Early in his career, McIntosh was the Program Manager for the Apollo 17, Infrared Scanning Radiometer that thermally mapped the dark side of the moon from lunar orbit. Later, he was employed at the Optical and Microlithography Groups of Perkin-Elmer Corp, Norwalk, CT.
Mr. McIntosh founded Horizon Technology Group, Inc. in 1986 and moved the company to Washington, DC. From 1986 to 1989, HTG provided proposal and strategic planning assistance to government agencies, companies, and research universities. Since 1989, HTG has performed R&D and SBIR contracts for the Navy, Air Force, DARPA, BMDO, and USDA for advanced sensing and semiconductor manufacturing technology. McIntosh was president of HTG until his retirement in 2004. He has 12 patents which he prosecuted pro se for capacitive sensors and sensor manufacturing methods.