Figure 5.

(a) Spectrum of escaping luminescence relative input light at different sensor implantation depth. The log-scale intensity axis highlights the exponential depth dependence. The sensor configuration was a single layer of tight-packed particles 100 μm in diameter with 100-μm center-to-center spacing (D100S100). (b) Ratio of total escaping luminescence power to the total input excitation power versus depth. Inset is log-scale plot. The environmental glucose concentration used for emission spectra was 250 mg∕dL. (The spectra obtained from prototype sensors exposed to 250 mg∕dL in vitro were used.) The absorption coefficient (@540 nm) was kept at 11.16 mm⁻¹. (c) Peak ratios of emission at 645 nm to that at 585 nm versus implantation depths.