Article

A triphasic analysis of negative osmotic flows through charged hydrated soft tissues

Department of Orthopaedic Surgery, Columbia University, New York, NY 10032, USA.
Journal of Biomechanics (Impact Factor: 2.5). 02/1997; 30(1):71-8. DOI: 10.1016/S0021-9290(96)00099-1
Source: PubMed

ABSTRACT Osmotic flow and ion transport in a one-dimensional steady diffusion process through charged hydrated soft tissues such as articular cartilage were analysed using the triphasic theory (Lai et al., 1991, J. biomech. Engng 113, 245-258). It was found that solvent would flow from the high NaCl concentration side to the low concentration side (i.e. negative osmosis) when the fixed charge density within the tissue (or membrane) separating the two electrolyte (NaCl) solutions was lower than a critical value. The condition for negative osmosis was derived based on a linear version of the triphasic theory. Distributions of ion concentration and strain field within the tissue were calculated numerically. Quantitative results of osmotic flow rates (ordinary and negative osmosis), ion flux and electric potential across the tissue during this diffusion process suggest that the negative osmosis phenomenon is due to the friction between ions and water since they could flow through the tissues at different rates and different directions.

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    • "So far, the triphasic mechano-electrochemical theory has been applied to model the mechanics of the articular cartilage [27] [28] [29] [30]. However the theory can be applied to any charged hydrated soft tissue made of an intrinsically incompressible, porous-permeable, charged solid phase; an intrinsically incompressible, interstitial fluid phase; and an ion phase with two monovalent ion species anion (-) and cation (+). "
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    • "A particular emphasis has been placed on the transport of ions in a charged, deformable solid matrix, as embodied in the triphasic theory of Lai et al. [8], the quadriphasic theory of Huyghe and Janssen [9], and the multielectrolyte theory of Gu et al. [10]. These investigations have often focused on mechanoelectrochemical phenomena arising from the transport of charged species within a charged matrix, such as streaming and diffusion potentials and currents [11] [12], Donnan osmotic swelling [8] [9] [10] [13], and phenomena such as reverse osmosis [14]. Finite element implementations of charged porous media have been presented by several authors, which are applicable to infinitesimal deformations [15] [16] [17] [18] [19] [20] and finite deformations [21]. "
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    • "Lai et al (1991) proposed a triphasic model of articular cartilage as an extension of the biphasic model, where negatively charged proteoglycans are modelled to be fixed to the solid matrix, and monovalent ions in the interstitial fluid are modelled as additional fluid phases. This model was later extended to incorporate multiple polyvalent ions by Gu et al. (1997,1999). Similar modification of the biphasic model to include thermo-chemo-electro-mechanical interactions in saturated charged porous solids was made by Huyghe and Janssen (1999), van Meerveld et al. (2003) and Zhang and Szeri (2007). "
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