Dielectrophoresis is defined as the force exerted on a dielectric particle in a non-uniform electric field. It can be used as a tool for precise on-chip colloidal manipulation and assembly and has been applied previously for making uniform structures from nano- and microparticles. In this study, we extend the method of controlled on-chip dielectrophoretic assembly to the making of permanent structures from live cells. Alternating electric fields were applied across suspensions of cells such as baker's yeast and NIH/3T3 mouse fibroblasts, to fabricate 1-D chains and 2-D arrays. The operating parameters such as voltage and frequency were optimized. The cells were further combined with synthetic inorganic nano- and microparticles to yield ultimate ?smart? materials. The particles were conjugated with lectins and attached to the cells irreversibly via biospecific lectin-polysaccharide interactions. Thus, they acted as biocolloidal binders between cells. The use of magnetic particles added an additional functionality to the live cell 2-D matrix and we were able to manipulate the material using an external magnetic field. Thus, we illustrate a simple novel technique to synthesize permanent functional bio-composite materials. A few applications of the new biocomposites include 1-D cell ?wires? in bioelectronic circuitry or 2-D cell membranes in sensors, coatings, bioreactors and biomedical implants.
