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. Author manuscript; available in PMC: 2018 Mar 31.
Published in final edited form as: Sens Actuators B Chem. 2016 Oct 18;241:398–405. doi: 10.1016/j.snb.2016.10.079

Figure 3.

Figure 3

a) Schematic diagram of system setup. The integrated system consisted of a CW Argon laser source, a prism, a shutter, a focusing lens, a free-space coupling stage, a detector, and a computer. The dual-core double-fiber twisted pH probe was integrated into the system and was applied for pH measurements in each well of a 96-well plate; b) A fluorescent spectra was plotted based on probe signal intensity range from 510 nm to 650 nm under a set of standardized pH buffer solution that ranged from pH 6.20 to pH 7.92. The vertical red and blue dash lines represent the peak (550 nm) wavelength and the reference wavelength (640 nm) for final ratio-based pH calculation (I550nm/I640nm); c) Linear correlation between buffer pH and fluorescent spectra peak intensity.