3.1. Design and fabrication of microchannels
Using the diffusion cell shown in Fig. 1, the permeability of the denaturant GdnHCl through the dialysis membrane was determined. Fig. 4 shows the time course of the GdnHCl concentration in the permeation chamber. Eq. (2) and the concentration from 0 to 60 minutes, in which the gradient of the GdnHCl solution concentration difference in the two chambers can be assumed to be constant. These data were used to determine the permeation coefficient P , which was calculated as 1.1 × 10−10 m2/s. The diffusion coefficient in the solution was about 5 × 10−10m2/s (Gannon et al., 2008). After 1440 min the concentrations in the feed and permeation chambers became almost equal. As the diffusion coefficient of GdnHCl was reported to be concentration dependent, and that at 1 M was around three times that at 5 M (Gannon et al., 2008), which is the concentration of feed used for the microchannel, P used for the microchannel design was collected with the scale factor.