Photonic Non-Invasive mmW and THz Imaging for Non-Melanoma Skin Cancer Detection

This paper proposes a contact-less non-invasive diagnostic technique for skin cancer detection and screening based on millimeter-wave (mmW) to terahertz (THz) photonic near-field imaging. Key photonic technologies required for developing multi-spectral sensors are fabricated and reported. This includes broadband photodiodes and wideband near-field antennas, both offering an operational frequency tuning range in excess of 0.2 THz and a maximum operational frequency beyond 0.3 THz. Furthermore, a compact photonic Ka-band mmW imaging sensor has been developed. The sensor head consists of a broadband photodiode for mmW signal generation and a Schottky barrier diode for incoherent power detection within the Ka-band. Calibration of the integrated sensor head is performed using a manufactured gelatin-based skin phantom. Calibration results reveal that the expected refractive index difference of 1 between healthy skin tissue and malignant squamous cell carcinoma (SCC) tumor in the mmW range can be easily detected. Finally, the principal function of the developed photonic imaging sensor is proven in the first in-vivo experiments using human skin tissue and skin tumor tissue (SCC). Experimental results indicate that the tumor can be clearly distinguished from healthy skin.