FIG. 1.

Antibody-functionalized obstacle arrays in a 2D microfluidic device can be used to engineer differential particle transport (left inset) and cell capture probabilities as a function of cell type, cell diameter (2a), array geometry (row spacing, Γ; column spacing, Λ; obstacle diameter, 2r; row offset, Δ), and flow rate. This paper studies the effect of DEP-assisted immunocapture, generated by applying an AC electric field to electrodes offset from the array and parallel to the direction of fluid flow. Target cells undergoing positive DEP (pDEP) are attracted to the high electric field magnitude regions at the obstacles leading and trailing edges (right inset), where the shear stress is low and the residence time is long (supporting the capture of the target cells); although they are also repelled from the low field magnitude regions at the obstacle shoulders, the locally high shear stress and short residence time minimizes the impact on overall capture. Likewise, contaminating cells undergoing negative DEP (nDEP) are repelled from regions where capture is likely (i.e., the obstacles' leading edge) and attracted to regions where capture is unlikely (i.e., the obstacles' shoulder).