Figure 3.

Selectivity, stability, repeatability, and linearity of the paper-based electrochemical sensors. (a) Selectivity of Ni-HHTP/SPCE for H₂O₂ detection (n = 9). (b) Changes in current generated by Ni-HHTP/SPCE in 0.1 M NaOH containing 50 μM H₂O₂ over 9 days. (c) Repeatability of Ni-HHTP/SPCE sensing in 0.1 M NaOH containing 50 μM H₂O₂ (n = 5). (d) CA of Ni-HHTP/SPCE at 0.4 V excitation potential for detection of different concentrations of H₂O₂ (inset shows the corresponding calibration curve of current versus H₂O₂ concentrations ranging from 0 to 5000 μM). (e) Selectivity of Ni-HHTP/SPCE Glu detection (n = 9). (f) Change in current generated by Ni-HHTP/SPCE in 0.1 M NaOH containing 100 μM Glu over 9 days. (g) Repeatability of Ni-HHTP/SPCE in 0.1 M NaOH containing 100 μM Glu (n = 5). (h) CV of Ni-HHTP/SPCE at different concentrations of Glu. Linear fitting curve of H₂O₂ concentration vs. current (inset shows the corresponding calibration curve of current versus Glu concentration).