Assessment of microalgae viability employing insulator-based dielectrophoresis

Microscale bioparticle analysis has advanced significantly providing advantages over bench-scale studies such as the use of a reduced amount of sample and reagents, higher sensitivity, faster response, and portability. Insulator-based dielectrophoresis (iDEP) is a microscale technique where particles are driven by polarization effects under a non-uniform electrical field created by the inclusion of insulators between two electrodes. iDEP possesses attractive advantages over traditional electrode-based dielectrophoresis since there is no electrode degradation and manufacture of the device is simpler and economical. This novel and powerful technique has been applied successfully in the manipulation of macromolecules and cells. In this study, differences in dielectric properties (cell membrane conductivity) of viable and non-viable microalgae, Selenastrum capricornutum, were employed to concentrate and separate a mixture of live and dead cells. A microchannel, manufactured in glass and containing an array of cylindrical insulating posts, was employed to dielectrophoretically immobilize and concentrate the mixture of cells employing direct current electric fields. Experiments showed that live cells exhibited a stronger dielectrophoretic response than dead cells, which allowed cell differentiation. Separation and enrichment of viable and non-viable microalgae was achieved in 35 s with a concentration yield of 10.36 and 15.87 times the initial cell concentration, respectively. These results demonstrate the use of iDEP as a technique for rapid assessment of microalgae viability; unveiling the potential of this powerful technique for environmental applications on lab-on-a-chip platforms.