Impact of Protein Adsorption on the Geometry of Microfluidics Devices

Abstract“Lab-on-a-chip” microfluidics devices manipulate biological fluids, which contain significant quantities of biomolecules, in particular proteins and DNA, and even living cells. As the dimensions of these devices continue to decrease and approach the sub-micron range, and as the trend towards “disposable” devices continues, the impact of the inevitable adsorption of biomolecules becomes more important. In this paper we estimated the protein-adsorption-related sensitivity of the geometry of a rectangular micron-sized channel. The estimation the thickness of the adsorbed protein layer versus processing parameters, i.e., protein concentration in the fluid; ionic strength of fluid; and surface tension of the walls, is based on a proposed semi-empirical model for protein adsorption. The model, derived from the data contained in a biomolecule adsorption database, uses the concept of a “generic protein”, i.e., a protein with molecular properties averaged over the range of data present in the database. The estimation of protein-adsorption-related impact on the geometry of a rectangular micron-sized channel, i.e., narrowing of the micro-channel, increases dramatically below a threshold value of approximately 1.5–2 μm.