Figure 3.

Long‐term operation of the bioresorbable pH sensor. a) Normalized photoluminescence intensity (red, at 580 nm) and mass of the porous scaffold (black) measured over ≈100 h on a pH sensor in buffer at pH 7.4 and 37 °C. b) Calibration curve (photoluminescence intensity at 580 nm versus pH value) of the pH sensor in (a) measured over the pH range 7.4–4 at t = 0, 50, and 95 h (n = 3 full cycles). c) Sensitivity value of the pH sensor in (b). d) Mass percentage of nPSiO₂ scaffolds oxidized in different conditions measured over time until full dissolution. The raw data are best‐fitted using a piecewise linear model (dotted traces). e) Dissolution rate of the SiO₂ capping layer and silicon skeleton of the nPSiO₂ scaffolds in (d) (n = 4 samples). f) Full dissolution time of the nPSiO₂ scaffolds in (d) (n = 3 samples). g) Time‐resolved normalized photoluminescence intensity (at 580 nm) of pH sensors on native Si in a flow cell and on PLGA foil under synthetic skin. h) Degradation rate (after 110 h of stable operation) of the photoluminescence of pH sensors on native Si in flow cell and on PLGA foil under synthetic skin (n = 3 samples). i) Photoluminescence stability and degradation times of pH sensors on native Si in flow cell and on PLGA foil under synthetic skin (n = 3 samples). Data are presented as mean (± s.d).