Bottom side partially etched D-shaped PCF biosensor for early diagnosis of cancer cells Shivam Singh, Bhargavi Chaudhary, Anurag Upadhyay and Sofyan A. Taya Eur. Phys. J. Plus, 138 6 (2023) 511 Published online: 08 June 2023 DOI: 10.1140/epjp/s13360-023-04133-8