Chip-scale optical detection of lung cancer with engineered photodetector based on distributed semiconductor heterojunctions

Abstract

Early detection of lung cancer is crucial because of the lower survival rate for improving treatment outcomes. Chip-scale photonic biosensors offer a promising label-free and non-invasive diagnostic approach by analyzing intercellular properties. Here, we demonstrate a chip-scale photonic platform based on semiconductor heterojunctions of n-type ZnO/TiO<inf>2</inf> with a comb-like structure to enable label-free detection of lung cancer cells. The lung cancer cells are detected using the engineered structure of the proposed photodetector through distinct fluctuations in the cells' electrical signature. The proposed voltage-controlled device configuration enhances interband transitions within the ZnO/TiO<inf>2</inf> depletion region with strong light-matter interaction, particularly in the UV spectrum. The proposed biosensor results in an enhanced photocurrent response in the presence of A549 cells, demonstrating its high sensitivity towards lung cancer detection. The photocurrent in PBS increases from 45 μA to 80 μA when a small concentration of A549 cells (500 cells/μl) is added at a low bias of 1.6 V, demonstrating label-free detection capability. The proposed device with its engineered structure combines ZnO's efficient charge carrier transport with TiO<inf>2</inf>'s proven biocompatibility, enabling sensitive and non-invasive analysis with an additional flexibility of voltage-controlled operation. The demonstrated on-chip biosensor can be a potential candidate for cancer detection, which can enable future integration with compact biosystems. © 2025 Elsevier B.V., All rights reserved.