title: 1D Measurement of Sodium Ion Flow in Hydrogel After a Bath Concentration Jump.
abstract: NMR is used to measure sodium flow driven by a 1D concentration gradient inside poly-acrylamid (pAA) hydrogel. A sodium concentration jump from 0.5 M NaCl to 0 M NaCl is applied at the bottom of a cylindrical pAA sample. The sodium level and hydrogen level are measured as a function of time and position inside the sample for 5 days. Then a reversed step is applied, and ion flow is measured for another 5 days. During the measurement, the cylindrical sample is radially confined and allowed to swell in the axial direction. At the same time, sodium and moisture in the sample are measured on a 1D spatial grid in the axial direction. A quadriphasic mixture model (Huyghe and Janssen in Int J Eng Sci 35:793, 1997) is used to simulate the results and estimate the diffusion coefficient of sodium and chloride. The best fit results were obtained for D[Formula: see text] cm(2)/s and D[Formula: see text] cm(2)/s, at 25 degrees centigrade. Different time constants were observed for swelling and deswelling.
authors: Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands, rroos@gmail.com.
authors: R W
authors: RW
authors: Roos
authors: L
authors: L
authors: Pel
authors: H P
authors: HP
authors: Huinink
authors: J M
authors: JM
authors: Huyghe
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D004058:Diffusion; D020100:Hydrogels / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D008962:Models, Theoretical; D012964:Sodium / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D014867:Water / Q000737:chemistry; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D020100:Hydrogels; D006859:Hydrogen; D012964:Sodium; D012965:Sodium Chloride; D014867:Water; D000099166:Polyacrylamides