Custom optical system for enhanced characterization and analysis of LSPR-based biosensors

Abstract

This paper presents the design and implementation of a tailored hyperspectral readout system for rapid characterization of transmission-based localized surface plasmon resonance (LSPR) biosensors. It addresses a gap in plasmonic research by offering high flexibility in experimenting with both chip synthesis and readout methodologies. The findings reported in this article can support the development of multiplexed LSPR array sensors with high sensitivity (120 nm/RIU), compact size (2 × 3 mm), and fast readout speed by providing optimal synthesis parameters, such as nanoparticle density and size, along with a robust foundation for designing an appropriate optical readout system. The setup incorporates a digitally controlled monochromator, offering high versatility in experimenting with the illumination’s wavelength, resolution and bandwidth. By employing a laser-excited phosphor source, integration times of the detector can be significantly reduced compared to Tungsten-Halogen light sources, resulting in enhanced signal-to-noise ratio and measurement time. Through a fully automated software-driven setup, the process of determining optimal chip design parameters, such as the density of nanoparticles and the size of the sensing spots, is streamlined. Additionally, simultaneous capture of illumination spectra is achieved for every measurement via a reference optical path with a spectrometer to mitigate measurement errors induced by source wavelength drift. Furthermore, the system facilitates straightforward detection of manufacturing errors, including misalignment or inhomogeneous particle distributions, enhancing overall efficiency and reliability for evaluating biosensors.