scholarly journals High-frequency acoustic sensors for operation in a gaseous medium. Final report

1990 ◽  
Author(s):  
G.S. Kino
Keyword(s):  
High Frequency ◽  
Gaseous Medium ◽  
Final Report ◽  
Acoustic Sensors

scholarly journals LDRD final report on Bloch Oscillations in two-dimensional nanostructure arrays for high frequency applications.

2008 ◽  
Author(s):  
Sungkwun Kenneth Lyo ◽  
Wei Pan ◽  
John Louis Reno ◽  
Joel Robert Wendt ◽  
Daniel Lee Barton
Keyword(s):  
High Frequency ◽  
Final Report ◽  
Two Dimensional ◽  
Bloch Oscillations ◽  
Nanostructure Arrays

Passive Wireless MEMS Microphones for Biomedical Applications

2005 ◽  
Vol 127 (6) ◽  
pp. 1030-1034 ◽  
Author(s):  
A. S. Sezen ◽  
S. Sivaramakrishnan ◽  
S. Hur ◽  
R. Rajamani ◽  
W. Robbins ◽  
...  
Keyword(s):  
High Frequency ◽  
Biomedical Applications ◽  
Impedance Change ◽  
Acoustic Sensors ◽  
Manufacturing Strategy ◽  
Wireless Monitoring ◽  
Wireless Telemetry ◽  
Mems Microphone ◽  
Mems Microphones ◽  
Sensor Package

This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, batteryless SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns.

scholarly journals Geomechanical modeling of distributed fiber-optic sensor measurements

2019 ◽  
Vol 7 (1) ◽  
pp. SA21-SA27 ◽  
Author(s):  
Christopher Sherman ◽  
Robert Mellors ◽  
Joseph Morris ◽  
Frederick Ryerson
Keyword(s):  
High Frequency ◽  
Fiber Optic ◽  
New Technology ◽  
Low Frequency ◽  
Rock Physics ◽  
Fiber Optic Sensor ◽  
Acoustic Sensors ◽  
Optic Sensor ◽  
Distributed Fiber Optic Sensor ◽  
Fracture Height

Fiber-optic-based distributed acoustic sensors (DAS) are a new technology that can be deployed in a well and are continuously interrogated during operations. These sensors measure the strain (or strain rate) at all points along the fiber and have been used extensively to monitor hydraulic stimulations. The data from these sensors indicate that they are sensitive to high-frequency signals associated with microseismicity and low-frequency signals associated with fracture growth. We have developed a set of idealized models to simulate these signals and to identify interpretation methods that may be used to estimate fracture location, geometry, and extent. We use a multiphysics code that includes rock physics, fluid flow, and elastic-wave propagation to generate synthetic DAS measurements from a set of simple models that mimic hydraulic fracturing. We then relate the signals observed in the synthetic DAS to specific features in the model such as fracture height, width, and aperture. Our results demonstrate that the synthetic DAS measurements may be used to interpret field DAS measurements and to optimize the design of future sensor deployments for sensitivity to fracture attributes.

scholarly journals High frequency response of fiber-optic planar acoustic sensors

1991 ◽  
Vol 9 (9) ◽  
pp. 1195-1199 ◽  
Author(s):  
J.A. Bucaro ◽  
N. Lagakos ◽  
B.H. Houston ◽  
A. Dandridge
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Fiber Optic ◽  
Acoustic Sensors ◽  
High Frequency Response
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