Enhancement of the volume refractive index sensing by ROTE and its application on cancer and normal cells discrimination

A volume refractive index (RI) sensor based on the resonant optical tunneling effect (ROTE) is presented in this study. Compared with the classic volume RI sensing structure, the Fabry-Pérot (FP) etalon, the ROTE structure has a higher figure of merit (FOM) than that of the FP cavity with the same cavity length. The sensitivity of the ROTE structure is almost 20 times as high as that of the FP structure, although the Q value of the ROTE structure is lower than that of the FP etalon. Given the excellent volume RI sensing performance of the ROTE structure, three groups of normal human cells and corresponding cancer cells were tested for discrimination in this paper. According to experimental results, the reflection resonant dips of each type of human cancer cell showed a red shift with respect to corresponding normal cells at the same density. The RI sensor based on the ROTE has broad application prospects in biomedical, drug screening, and early cancer diagnoses.