A plasmonic refractive index sensor with high sensitivity and its application for temperature and detection of biomolecules

In this paper, a metal–insulator–metal waveguide is paired with a hexagonal irregular ring resonator to construct a high sensitivity refractive index plasmonic nano-sensor in this work. The sensing properties of the proposed design are studied using a numerical solution in the finite-difference time-domain. The acquired results reveal a linear connection between the material's refractive index (RI) and the wavelength of resonances. Furthermore, the maximum linear sensitivity for the second mode is S = 2417 nm/RIU, with a figure of merit (FOM) of 38, whereas the highest for the first mode is S = 1002 nm/RIU, with a FOM of 28.6. With a sensitivity of 1.02 nm/°C, this sensor is also being examined as a temperature sensor. When ethanol is employed as the measuring liquid, the sensor's operating temperature range is between—114.3 and 78 °C. This device can create a path toward RI by being highly sensitive for the label-free diagnosis of different molecules and providing temperature sensing abilities. It can also be used in microchip processors and has a wide spectrum of biological applications.