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Optically excited nanoscale ultrasonic transducers
Journal article   Open access   Peer reviewed

Optically excited nanoscale ultrasonic transducers

Richard J Smith, Fernando Perez Cota, Leonel Marques, Xuesheng Chen, Ahmet Arca, Kevin Webb, Jonathon Aylott, Micheal G Somekh and Matt Clark
The Journal of the Acoustical Society of America, Vol.137(1), pp.219-227
01/2015
DOI: 10.1121/1.4904487
PMID: 25618053
url
https://doi.org/10.1121/1.4904487View
Published (Version of record) Open Access

Abstract

In order to work at higher ultrasonic frequencies, for instance, to increase the resolution, it is necessary to fabricate smaller and higher frequency transducers. This paper presents an ultrasonic transducer capable of being made at a very small size and operated at GHz frequencies. The transducers are activated and read optically using pulsed lasers and without physical contact between the instrumentation and the transducer. This removes some of the practical impediments of traditional piezoelectric architectures (such as wiring) and allows the devices to be placed immediately on or within samples, reducing the significant effect of attenuation which is very strong at frequencies above 1 GHz. The transducers presented in this paper exploit simultaneous optical and mechanical resonances to couple the optical input into ultrasonic waves and vice versa. This paper discusses the mechanical and optical design of the devices at a modest scale (a few μm) and explores the scaling of the transducers toward the sub-micron scale. Results are presented that show how the transducers response changes depending on its local environment and how the resonant frequency shifts when the transducer is loaded by a printed protein sample.
Models, Theoretical Photoacoustic Techniques - instrumentation Serum Albumin, Bovine - analysis Transducers Lasers Signal-To-Noise Ratio Nanotechnology - instrumentation Ultrasonics - instrumentation Equipment Design

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