Fig. 2: Glow chemi-excitation of fluorescent particles.

a Emission spectra of optically-excited (dashed lines) and chemi-excited (solid lines) 0.2 μm FluoSpheres Microspheres (blue, Excitation 365 nm/ Emission 415 nm; green, Excitation 505 nm/Emission 515 nm; red, Excitation 580 nm/Emission 605 nm; 2 × 10¹⁰ particles in 50 μL butyl benzoate) and 0.28 μm latex particles in-house dyed with 9,10 diphenylanthracene (Excitation 350–395 nm/ Emission 400–450 nm; black lines). Optically-excited emission spectra were obtained with a Tecan M200PRO microplate reader. Chemi-excitation emission spectra were obtained by mixing particles with TCPO/H₂O₂ and recording emission spectrum with excitation set to irrelevant 850 nm. b Detectability of chemi-excited fluorescent particles by a smartphone camera versus optically-excited fluorescent particles by a Tecan M200PRO plate reader. Top: Optically-excited fluorescence (log scale) of a dilution series read using a plate reader. FluoSpheres Microspheres (blue, green, and red particles as described in (a) were twofold serially diluted into a black 96-well plate and measured at their corresponding excitation and emission wavelengths (n = 3; average ± 1 Std Dev). Middle: FluoSpheres Microspheres chemi-excited with glow excitation solution and imaged with a smartphone (n = 3; average ± 1 Std Dev). Bottom: Intensity profiles (log scale) for chemi-excited particles were extracted from images above (b) using ImageJ and normalized by the no-particle signal as described in Methods.