Millimeter-Wave Near-Field Probe Designed for High-Resolution Skin Cancer Diagnosis
Fritzi Töpfer, Sergey Dudorov, Joachim Oberhammer
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
Vol. 63, No. 6
pp. 2050 - 2059
Dielectric waveguides, medical applications, micromachining, millimeter waves, near-field probes
This paper presents a detailed technical characterization of a micromachined millimeter-wave near-field probe developed for skin cancer diagnosis. The broadband probe is optimized for frequencies from 90 to 104 GHz and consists of a dielectric-rod waveguide, which is metallized and tapered towards the tip to achieve high resolution by concentrating the electric field in a small sample area. Several probes with different tip sizes were fabricated from high-resistivity silicon by micromachining and were successfully characterized using silicon test samples with geometry-defined tailor-made permittivity. The probes show a high responsivity for samples with permittivities in the range of healthy and cancerous skin tissue at 100 GHz (from to , loss tangent of approximately 1.26). The sensing depth was determined by simulations and measurements from 0.3 to 0.4 mm, which is adapted for detecting early-stage skin tumors before they metastasize. The lateral resolution was determined to 0.2 mm for a tip size of 0.6 0.3 mm, which allows for resolving small skin tumors and inhomogeneities within a tumor.
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