A Newly Developed mm-Wave Sensor for Detecting Plaques of Arterial Vessels

Abstract

Background Microcalcifications within the fibrous cap of the arteriosclerotic plaques lead to the accrual of plaque-destabilizing mechanical stress. New techniques for plaque screening with small detectors and the ability to differentiate between the smooth and hard elements of plaque formation are necessary.

Method Vascular plaque formations are characterized as calcium phosphate containing structures organized as hydroxylapatite resembling the mineral whitlockite. In transmission and reflexion studies with a simple millimeter wave (mm-wave)–demonstrator, we found that there is a narrow window for plaque detection in arterial vessels because of the tissue water content, the differentiation to fatty tissue, and the dielectric property of air or water, respectively.

Result The new sensor is based on a sensing oscillator working around 27 GHz. The open-stub capacitance determines the operating frequency of the sensor oscillator. The capacitance depends on the dielectric properties of the surrounding material. The sensor components were completely built up in surface mount technique.

Conclusion Completed with a catheter, the sensor based on microwave technology appears as a robust tool ready for further clinical use.

Keywords

atherosclerosis - bioengineering - dielectric spectroscopy - mm-wave catheter

Authors' Contributions

Sebastian Vogt, MD, JW, CW and RR wrote the manuscript. Sebastian Vogt, Wilhelm Nimphius, Anette Ramaswamy, and Rabia Ramzan performed the histological studies and clinical applications. Markus Detert, David Wagner, and Ulrich Schumann developed electronic hardware design. Jan Wessel, Christian Wenger, Subhajit Guha, Farabi Ibne Jamal, and Mohammed Hussein Eissa finalized sensor assembly and were involved in experimental procedures together with Sebastian Vogt, Jan Wessel, Christian Wenger, Rabia Ramzan, and Wilhelm Nimphius, Betram Schmidt, Georg Rose, Anette Ramaswamy, Gordon Notzon, Christoph Bear, Christoph Dahl, Ilona Rolfes, and Thomas Musch adapted catheter in different experimental settings.

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