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.