Fig. 1. (Color online) (a) A diagrammatic representation of the water-dispersible F127-dodecyl-Si QDs:Er micelles. (b) Photographs under fluorescent lamp illumination of dodecyl-Si QDs:Er in toluene (left) and aqueous F127-dodecyl-Si QDs:Er assembled with 10 mg·mL⁻¹ F127 (right). (c) TEM image of dodecyl-Si QDs:Er. An HR-TEM image is shown as the inset. (d) Dodecyl-Si QDs:Er size distribution. (e) PL spectral comparison between dodecyl-Si QDs:Er in toluene and aqueous F127-dodecyl-Si QDs:Er solutions at different F127 concentrations (2 to 20 mg·mL⁻¹). (f) F127 concentration dependence of the F127-dodecyl-Si QDs:Er PL intensity. (g) Effect of F127 concentration on the PL peak wavelength (λ) for F127-dodecyl-Si QDs:Er.

Fig. 2. (Color online) (a) PL spectra of F127-dodecyl-Si QDs:Er with varying Fe³⁺ concentrations. (b) Correlation between ratiometric fluorescence response and Fe³⁺ concentrations (0−100 mM). Linear fits of the intensity ratio versus Fe³⁺ concentration in the ranges of (c) 0−0.01 mM and (d) 10−100 mM. (e) Comparison of detection performance metrics to previously reported QDs-based Fe³⁺ nanosensors. (f) Selectivity and anti-interference of the F127-dodecyl-Si QDs:Er nanosensor. All metal ions present are at a concentration of 5 mM.

Fig. 3. (Color online) (a) FTIR −OH peak of F127-dodecyl-Si QDs:Er with varying Fe³⁺ concentration. (b) PL lifetime of F127-dodecyl-Si QDs:Er under different Fe³⁺ concentrations. (c) O 1s XPS spectrum of F127-dodecyl-Si QDs:Er in the absence or presence of Fe³⁺. C_Fe = 5 mM. (d) Fe 2p XPS spectrum of FeCl₃ in the absence or presence of F127-dodecyl-Si QDs:Er. C_Fe = 5 mM. (e) Schematic of the fluorescence quenching mechanism for F127-dodecyl-Si QDs:Er with Fe³⁺.

Fig. 4. (Color online) (a) Bar plot of sequential logic function using the Δc and c_T as inputs. (b) Output (OFF/ON) resulting from different input sequences and the corresponding truth tables. (c) Graphical illustration for the input of sequential logic function and crossword puzzle analogy.