Picture of athlete cycling

Open Access research with a real impact on health...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by Strathclyde researchers, including by researchers from the Physical Activity for Health Group based within the School of Psychological Sciences & Health. Research here seeks to better understand how and why physical activity improves health, gain a better understanding of the amount, intensity, and type of physical activity needed for health benefits, and evaluate the effect of interventions to promote physical activity.

Explore open research content by Physical Activity for Health...

Piezoelectric ultrasonic transducers with fractal geometry

Mulholland, A. J. and Walker, A. J. (2011) Piezoelectric ultrasonic transducers with fractal geometry. Fractals, 19 (4). pp. 469-479. ISSN 0218-348X

Full text not available in this repository. Request a copy from the Strathclyde author

Abstract

Piezoelectric ultrasonic transducers typically employ composite structures to improve their transmission and reception sensitivities. The geometry of the composite is regular with one dominant length scale and, since these are resonant devices, this dictates the central operating frequency of the device. In order to construct a wide bandwidth device it would seem natural therefore to utilize resonators that span a range of length scales. In this article we consider such a device and build a theoretical model to predict its performance. A fractal medium is used as this contains a wide range of length scales and yields to a renormalization approach. The propagation of an ultrasonic wave in this heterogeneous medium is then analyzed and used to construct expressions for the electrical impedance, and the transmission and reception sensitivities of this device as a function of the driving frequency. The results presented show a marked increase in the reception sensitivity of the device.