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. Author manuscript; available in PMC: 2013 Jul 14.
Published in final edited form as: Soft Matter. 2012 May 28;8(26):2897–2905. doi: 10.1039/C2SM25783A

FIGURE 4.

FIGURE 4

(A) Model results for the ion concentrations based on the experimentally measured voltage and E-gel growth curves (Fig. 3). For clarity, concentrations of H+ ions are displayed as positive and OH− concentrations are inverted and appear as negative. The dashed line indicates the separation between the H+ and OH− domains. The boundary between the E-gel and the silk solution is x=0.6 cm, the final value of the E-gel depth in Fig. 3b. (B) pH profile calculated by converting ion concentration values of (A) into pH (Eqs. 6,7). The numerical pH results agree well with the experimentally measured pH distribution obtained using the pH probe (Fig. 1c,d). The coordinate x=0 is the (+) plate and x=L=1 cm is the (−) plate (Fig. 2).