An open and low-cost optical-fiber measurement system for the optical detection of oxygen using a multifrequency phase-resolved method

Electrophoretic deposition as a new approach to produce optical sensing films adaptable to microdevices

“…According to the Demas model, the response to oxygen for all the chips suggests the existence of two sites within the matrix: a rst fraction of sites (f 1 ) possessing a high k SV1 , and a second fraction of sites (f 2 ), whose contribution is very small compared to f 1 , presenting less sensitivity. The values for k SV1 found for the sensing lms are in agreement with the results found for a classical PS membrane (k SV1 ¼ 40.31 AE 3.90 bar À1 ) 25 and a PSMA membrane deposited over a glass support (k SV1 ¼ 49.25 AE 1.55 bar À1 ; see Table 2), which were also the same than those obtained for a gold chip drop-coated with PSMA particles and dried under vacuum. The same oxygen behavior, regardless of the amount of particles deposited, hints that even at 250 nm thickness the sensitivity to oxygen is still restricted by the polymer permeability to oxygen as well as the distribution of the dye inside the polymeric material.…”

“…Excitation and emission spectra were obtained with a Varian Cary-Eclipse luminescence spectrometer (Varian Inc.-Agilent Technologies, http://www.agilent.com, CA, USA) equipped with a Xe ash lamp (peak power equivalent to 75 kW), Czerny-Turner monochromators, and a red-sensitive photomultiplier tube (PMT) R-928 from Hamamatsu Photonics (http:// www.sales.hamamatsu.com, Japan) with a manual or automatic voltage regulator. In addition, a customized version of the optical ber measurement system previously described 25 (see Fig. ESI-1 †) was used to characterize the sensitivity to oxygen of the sensing layers. For this purpose, the phaseresolved method described in the ESI † was applied using a commercial dual lock-in amplier as the phase-sensitive detector.…”

“…ESI-3 † shows the excitation and emission spectra of the chip obtained at the highest potential and time (40 V cm À1 and 10 min), showing no change in the spectroscopic properties compared to the dye in solution or in a classical polystyrene (PS) membrane. 25,40 It shows three excitation peaks, at $390, 508 and 540 nm, corresponding to the Soret and Q bands of platinum porphyrins. In addition, the emission peak at 650 nm was completely quenched in the presence of oxygen.…”

“…† Assuming that the luminescence decay is monoexponential, the relationship between the emission lifetime s (in seconds) and the phase shi F (in radians) is given by expression (1), where f is the modulation frequency (in Hz). 9,25 s ¼ tanF 2pf…”

Self-Referenced Multifrequency Phase-Resolved Luminescence Spectroscopy

“…Chemical sensing based on quenched luminescence has become increasingly popular in the last decades due to its versatility and accuracy at a reasonable cost [ 1 , 2 , 3 , 4 , 5 , 6 ]. Different schemes for measuring the luminescence, including emission intensity and luminescence lifetime measurements are reported in the literature [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”