Development of the prism-coupler model for the design of a biosensor based on SPR technology for fast diagnostics

Biosensors are considered the tools of the future in medicine. With the pandemic caused by the new corona-virus (SARS-COV-2), the development of biosensors with fast diagnostics has become a public health need. Optical biosensors, in particular, have gained strength in the market due to their high sensitivity and detection capability. In this category, sensors based on surface plasmon resonance technology have gained prominence. In this work, a prism-coupler set using the Ktreschamnn configuration was designed and built. The prism-coupler smodel consists of an automated optical-mechanical system and a triangular prism. Thin films of 50 nm of gold and 5 nm of titanium were deposited on glass slices and coupled to a commercial prism (refractive index 1.50). The movement of the optical-mechanical system and the data acquisition are carried out by 2 microcontrollers that are configured using a Labview software. A simulation program using MatLab software was also developed in this work to determine the SPR curves at different refractive index solutions. At first, measurement in air was carried out obtaining a resonance angle in 35°. Afterwards, sucrose solutions were measured using our system at concentrations of 10, 20, 30, 40 and 50%. Finally, experimental and simulated results were compared and analyzed in this work.