A Portable Surface Plasmons Resonance Sensor Based on Single-Board Computer

Abstract

The development of portable surface plasmons resonance (SPRs) are recently boosted by the use of instrumentation based on small-size single-board computer (SBC) platforms. The SPR and SBC combination is ideal for advances in direction of miniaturization and portability, however many scientific and engineering solutions yet required a computer connection for operation, and reported portable sensors in which hardware and software resources are misused. Here a standalone portable SPR based on an SBC is presented. The sensor operates without the need for another device, computer, or connection. Designed to work with thicker (3 mm thick) or thin (1.5 mm) biochips to support surface plasmons (SPs) and avoid rotational parts, a set of special structures was designed to encapsulate all electronics and optical elements. Composed of modular parts manufactured in a 3-D printer, the proposed arrangement enables quick maintenance and repair actions, eventually required for field applications. The chassis piece enclosure the components and fit the touchscreen. A replaced top cover piece enables the exchange of the thicker- and thin- biochips. And a back lid gives access to the internal components, where moving parts are designed and included to improve mechanical alignment. The sensor was optimized to Raspberry Pi SBC. The Python-based embedded software implements algorithms for acquiring, processing, displaying, storing, and delivering the SPR responses. To demonstrate the solution feasibility a Raspberry pi 3 model B was used. The well knows biochips PPBIO (Prism BIOchip) (thicker) and diffractive optical coupling element (DOCE) (thin) were attached to the proposed SBC-SPR Sensor. Those biochips dismissed index-matching gels and rotate parts, which benefits the sensing labor cost. Experiments of aqueous solutions were performed with a sensor operating in the so-called angular interrogation mode (AI mode). The results indicate the capability of phenomena excitation and sensor arrangement. The sensitivity figure-of-merit (FOM) was achieved in the order of 160°/RIU, similar to the performance of traditional set-up for those biochips.