Cancer Biomarkers Ultrasensitive Detection Based on Terahertz Frequency-Comb-Like

Terahertz (THz) biosensors provide a new avenue for the early diagnosis and treatment of cancers. However, conventional THz biosensors cannot achieve high sensitivity due to limited absorption peaks. In this work, we propose a cancer biomarker ultrasensitive detection method based on THz frequency-comb-like. First, we design a basic biosensor that has three resonant absorption peaks. Then, we proportionally change the size of basic biosensor and obtain other four biosensors with different resonant absorption peaks. Finally, a frequency-comb-like containing eight uniformly spaced absorption peaks in the range of 0.5–1.3 THz is realized by appropriately selecting the absorption peaks of these five biosensors. Three cancer biomarkers of carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and squamous cell carcinoma (SCC) are used as samples of experiment. Under the same concentration, the frequency shifts generated by each peak are accumulated. For samples from 0.1 pg/mL to 50 ng/mL, the cumulative frequency shifts are 122–547, 168–815, and 142–505 GHz. The sensitivity ( $S_{c}$ ) of concentration is 64.995, 105.005, and 62.634 GHz/log(ng/mL). The limit of detection (LOD) is 0.1 pg/mL. Compared with other methods using single or few resonant absorption peaks, this method shows higher sensitivity and lower LOD. Therefore, it is valuable for trace molecule detection, biomedical sensing, and cancer diagnosis at early stage.