United States of America As Represented by the Administrator of Nasa

Creare, Incorporated

Robert Kline-Schoder

Patrick Magari

Shinzo Onishi

David B Kynor

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

Bubble measuring instrument and method

An ultrasonic transducer array having a plurality of transducer elements, at least some of which have multiple piezoelectric and electrode layers. The resonant frequency of the transducer elements may range from 500 kHz to 300 MHz or more. A single array may have transducer elements of different resonant frequencies, and the array may be sparsely populated. Highest frequencies are typically obtained when the piezoelectric layers are made from vapor deposited PZT in accordance with a disclosed deposition process. The array may have a 1-D configuration, 1.5-D or 2-D, configuration. The array may be positioned in a probe.

Multilayer ultrasonic transducer array including very thin layer of

An ultrasonic imaging system capable of transmitting and receiving ultrasound over a wide frequency range, i.e., 500 KHz-300 MHz. Ultrasound may be transmitted from a single transducer array at multiple frequencies simultaneously or sequentially via separate, acoustically isolated transducer elements, each having a unique resonant frequency. Signal-to-noise ratio may be enhanced through use of multiple piezoelectric layer transmit transducer elements and single piezoelectric layer receive transducer elements, both on a single transducer array. Aspect ratios approaching unity for transducer elements of the array may be obtained, which can be used to reduce grating lobes. Sparsely populated transducer arrays are included in the imaging system. Methods of ultrasound imaging and ultrasound therapy obtainable with the present imaging system are included in the invention.

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Norwich, VT, United States of America

Robert Kline-Schoder