title: Combined "dual" absorption and fluorescence smartphone spectrometers.
abstract: A combined "dual" absorption and fluorescence smartphone spectrometer is demonstrated. The optical sources used in the system are the white flash LED of the smartphone and an orthogonally positioned and interchangeable UV (λex=370  nm) and blue (λex=450  nm) LED. The dispersive element is a low-cost, nano-imprinted diffraction grating coated with Au. Detection over a 300 nm span with 0.42 nm/pixel resolution was carried out with the camera CMOS chip. By integrating the blue and UV excitation sources into the white LED circuitry, the entire system is self-contained within a 3D printed case and powered from the smartphone battery; the design can be scaled to add further excitation sources. Using a customized app, acquisition of absorption and fluorescence spectra are demonstrated using a blue-absorbing and green-emitting pH-sensitive amino-naphthalimide-based fluorescent probe and a UV-absorbing and blue-emitting Zn2+-sensitive fluoro-ionophore.
authors: Md
authors: M
authors: Arafat Hossain
authors: John
authors: J
authors: Canning
authors: Sandra
authors: S
authors: Ast
authors: Kevin
authors: K
authors: Cook
authors: Peter J
authors: PJ
authors: Rutledge
authors: Abbas
authors: A
authors: Jamalipour