Biosensor For The Detection Of Cell By Resonant Optical Tunneling Effect

The incidence of cancer is increasing year by year,and the detection and treatment of cancer has attracted widespread attention.Early detection and treatment of cancer is extremely important to improve the cure rate of cancer patients.The method based on refractive index(RI)measurements has the advantages of rapid,label-free detection and real-time monitoring for discriminating the cancer/normal cells.Compared with the classic RI sensing structure,the sensing structure based on the resonant optical tunneling effect(ROTE)has higher resolution and can distinguish cancer/normal cells at low cell concentration.Firstly,the reflection spectra formula of multilayer dielectric structure is deduced by the transmission matrix method.The sensing performance of the ROTE cavity and Fabry Pérot(FP)cavity are simulated and analyzed based on the simulation software,respectively.The RI sensitivity characteristics of the ROTE and FP structures are verified by changing the RI of the cavity,and the sensitivity,quality factor and figure of merit of the two sensors are also characterized and compared.The results show that although the Q value of ROTE is lower than that of FP etalon,the RI sensitivity of the ROTE structure is almost 20 times as high as the FP structure.The ROTE structure has higher FOM than that of the FP cavity with the same cavity length.The effect of coupling loss and material absorption on the quality factor of the two sensing structures are analyzed by simulation.Then,the ROTE multilayer sensitive structure is prepared based on the simulation results,and the experimental test system is established.The performance calibration of ROTE sensor shown the Q value of 600 and the RI sensitivity of 19,200 nm/RIU.The cancer and normal cells discrimination scheme is designed based on the ROTE structure.Three groups of normal human cells(human stomach cells,human liver cells,human skin cells)and corresponding cancer cells are tested for discrimination,and each reflection spectrum maintains a good discrimination,and the results of the experiment is analyzed by mathematical statistics.Finally,in order to improve the performance of the sensor,a RI sensor based on the Mach-Zehnder(MZ)interference is designed by combining ROTE structure with interference structure.Compared with reflection spectrum of the ROTE structure,the MZ interference structure greatly improved the resolution of the ROTE sensor based on the high sensitivity of the original structure.The RI sensor based on the ROTE has broad application prospects in biomedical,drug screening,and early cancer diagnoses.