Multi-layered MXene and GST Material–Based Reflective Index Sensor: Numerical Study and Predication of Behaviour Using Machine Learning

We proposed the multi-layered structure formed with two-dimensional and phase change materials for designing reflective index sensors. We have used the phased change material as composited Ge₂Sb₂Te₅ (GST) and Ti₃C₂T_X (MXene) to improvise sensitivity and tunable behaviour. The overall structure is formed with Si–MXene–Si–GST–Si–Au–analyte multi-layered materials. The proposed structure is numerically investigated for the infrared frequency range of 187 to 200 THz (1.5–1.6 µm). The structure can detect the RI from 1 to 2.5, covering the basic refractive index values of several biomolecules such as haemoglobin, urine, saliva, cortisol, glucose and cancerous cells. We have presented the behaviour of the structure for the different X and Y input polarization conditions. The structure is also numerically investigated for physical parameters like material height and the resonator’s dimensions. This structure offers constant reflectance operation under the wide input incident oblique angle (0 to 80°) condition. The overall structure provides the maximum and minimum sensitivity variation as 6.5 THz/RIU and 144 THz/RIU, which also can be represented as 208 nm/RIU to 4615 nm/RIU. The proposed structure’s optimized behaviour and performance are investigated using the Artificial neural network prediction model. This model can predict the behaviour of the overall structure with R² = 0.956. The wideband of the refractive index sensing behaviour and tunable approach of the GST material makes this device very suitable for developing universal biomolecule sensors where specific refractive index values are considered.