Dielectrophoresis (modeling, lab/chip)

Dielectrophoresis is the motion of polarizable particles in a nonuniform electric field. Electropatterning systems bvsed on dielectrophoretic forces are able to localize single cells within a fluid volume to micron-scale resolution, providing precise control over cell shape, organization, and their interactions. Such electrokinetic systems move living cells rapidly toward positions dictated by the local electric field strength established via micropatterned surface electrodes. We have developed several models and experimental systems that enable DEP-based manipulation of both biological and non-biological particles (Albrecht et al, 2004). In the movie below, 10 µm latex particles were aligned in water by dielectrophoresis (DEP) upon activation of a high frequency AC electric field between the electrodes (vertical stripes). We have used these active cell manipulation tools to create well-defined patterns of live cells within tissue engineering scaffolds, such as hydrogels. Cells become encapsulated in a tissue-like 3D environment, yet the precise positioning allows control of cell-cell and cell-matrix interactions. For example, we have patterned live hepatocytes within a flexible 100 µm thick hydrogel slab (top, right) by DEP cell patterning. (bottom: patterned gel, folded) This technique to organize cells is complementary to gel patterning via photopolymerized hydrogels , another technology being developed in the lab. Together, they can control 3D cellular architecture at various length scales (cell: 10 µm; tissue functional unit; 100 µm), allowing us to probe more deeply into the effects of the cell microenvironment on the behavior and function of tissue-engineered constructs.

Click the image above to watch a movie of the beads (332k)