Design of an Optical Biosensing Platform Based on a Trapezoidal Prism

This article presents the design, development, and characterization of a Surface Plasmon Resonance (SPR) biosensing platform for point-of-care (POC) applications. The platform employs a custom image acquisition system with a Hamamatsu S11661 CMOS sensor and an STM32F407VE microcontroller, operating in angular interrogation mode (AIM) with a prism-based polymeric transducer (PPBIO). Low-cost, 3D-printed optomechanical components ensure optical alignment and focal adjustment. Experimental evaluations demonstrate the system’s capability to detect refractive index variations, effectively distinguishing between water and phosphate-buffered saline (PBS) samples. Three minimum detection algorithms (DBL, PLF, LPDIFF) are compared. The results, including a sensitivity of approximately 111°/RIU and a total power consumption below 0.5 W (excluding the microfluidic system), underscore the platform’s potential. Its low cost and portability support its viability for future use in POC diagnostics and eventual expansion for IoT system integration.