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. Author manuscript; available in PMC: 2022 Nov 28.
Published in final edited form as: ACS Sens. 2019 Sep 5;4(9):2367–2374. doi: 10.1021/acssensors.9b00962

Figure 2.

Figure 2.

Sensor design. (a) The sensor consists of two layers: A top pH-indicating film made of PEG hydrogel with encapsulated BCG dye. A bottom layer of scintillating particles (Gd2O2S:Eu) encapsulated in PDMS and covered by the pH sensing film. (b) Luminescence spectrum of scintillators (Gd2O2S:Eu) (red line, left y -axis) and the extinction spectra of BCG-doped PEG films in pH 3.0 buffer (yellow line, right y-axis) and pH 7.0 buffer (blue line, right y-axis). Inset: Sensor discs (scintillator + pH film) showing color change at acidic pH (yellow), physiological pH (blue-green) and reference disc (white) containing only scintillators with no pH film covering it. (c) Scintillator radioluminescence spectrum after passing through the BCG pH dye in PEG hydrogel at different pH. Inset: Ratio of 620 and 700 nm intensities plotted for each pH (ratio vs. pH on log scale available in ESI, S2).