Figure 5
From: High fidelity fibre-based physiological sensing deep in tissue
pH response of the optrode and separate fluorophores. (A) Fluorescence emission spectra of “saturated” loaded FAM (solid lines) and TAMRA (dotted lines) microspheres at different pH. (B) Fluorescence emission spectra of FAM only (blue line) and TAMRA microspheres (orange line) at pH 7. Fluorescence emission spectra at pH 7 of FAM and TAMRA microspheres when numerically combined (green line) is compared to the spectral shape of the fabricated FAM/TAMRA probe (black line, halved in amplitude to aid comparison). (C) Fluorescence emission spectra of the FAM/TAMRA pH sensor at different pH. The FAM dominant region is highlighted as A1 (λ < 562 nm) and TAMRA dominant region as A2 (λ > 562 nm). (D) Calculated ratio of fluorescence intensity from the measured spectra at different pH (n = 3). The ratio was calculated by dividing the area under the curve of spectral region A2 by A1. All measurements were from a single sensor from one core of the optrode at 520 nm (Power 10 µW and 100 ms exposure time). Uncertainty in measurement was calculated to be ±0.02 pH units (standard deviation, see methods).
