Planar Microwave Sensor for Theranostic Therapy of Organic Tissue Based on Oval Split Ring Resonators.
Microwave sensors in medical environments play a significant role due to the contact-less and non-invasive sensing mechanism to determine dielectric properties of tissue. In this work, a theranostic sensor based on Split Ring Resonators (SRRs) is presented that provides two operation modes to detect and treat tumor cells, exemplary in the liver. For the detection mode, resonance frequency changes due to abnormalities are evaluated, and in the treatment mode, microwave ablation is performed. The planar sensor structure can be integrated into a needle like a surgery tool that evokes challenges concerning size limitations and biocompatibility. To meet the size requirements and provide a reasonable operating frequency, properties of oval shaped SRRs are investigated. By elongating the radius of the SRR in one direction, the resonance frequency can be decreased significantly compared to circular SRR by a factor of two below 12 GHz. In order to validate the detection and treatment characteristics of the sensor, full wave simulations and measurements are examined. Clear resonance shifts are detected for loading the sensor structures with phantoms mimicking healthy and malignant tissue. For treatment mode evaluation, ex vivo beef liver tissue was ablated leading to a lesion zone 1.2 cm × 1 cm × 0.3 cm with a three minute exposure of maximum 2.1 W.
Institute for Microwave Engineering and Photonics, Technische Universität Darmstadt, Merckstr. 25, Darmstadt 64283, Germany. reimann@imp.tu-darmstadt.de.
Carolin
C
Reimann
Institute for Microwave Engineering and Photonics, Technische Universität Darmstadt, Merckstr. 25, Darmstadt 64283, Germany. puentes@imp.tu-darmstadt.de.
Margarita
M
Puentes
Terahertz Sensors Group, Technische Universität Darmstadt, Merckstr. 25, Darmstadt 64283, Germany. maasch@imp.tu-darmstadt.de.
Matthias
M
Maasch
Institute of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main 60590, Germany. Frank.Huebner@kgu.de.
Frank
F
Hübner
Institute of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main 60590, Germany. Babak.Bazrafshan@kgu.de.
Babak
B
Bazrafshan
Institute of Diagnostic and Interventional Radiology, Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main 60590, Germany. Thomas.Vogl@kgu.de.
Thomas J
TJ
Vogl
Terahertz Sensors Group, Technische Universität Darmstadt, Merckstr. 25, Darmstadt 64283, Germany. damm@imp.tu-darmstadt.de.
Christian
C
Damm
Institute for Microwave Engineering and Photonics, Technische Universität Darmstadt, Merckstr. 25, Darmstadt 64283, Germany. jakoby@imp.tu-darmstadt.de.
Rolf
R
Jakoby
microwave ablation; oval split ring resonator; theranostics