Portable low-cost instrumentation for monitoring Rayleigh scattering from chemical sensors based on metallic nanoparticles.

Using a Hg(II) sensor based on the aggregation of gold nanoparticles as a model system, we evaluated the performance of two portable low-cost devices that monitor the wavelength-ratiometric resonance Rayleigh scattering signal of the chemical sensor upon white-LED illumination. The first device uses two optical filter-photodiode combinations to detect scattered light while the second employs a novel ultra-compact (grating-free) spectral sensor. Results show that the response of the Hg(II) sensor monitored with these devices is comparable to that measured using a high-end benchtop scanning spectrofluorometer.