Combined alternating current electrothermal and dielectrophoresis-induced tunable patterning to actuate on-chip microreactions and switching at a floating electrode

A unique platform to fabricate tunable micropatterns at an electrically floating electrode has been developed via an enhanced combination of dielectrophoresis (DEP) and alternating current electrothermal (ACET) processes. The design of the platform uses two pairs of driving electrodes to generate a tunable electric field at a floating electrode, which in turn allows for the formation of patterned cells and fluids with desired features. By regulating the input configuration of the ac signals, yeast cells can be either patterned at the field stagnant region by a synergistic combination of negative DEP and ACET flow, or partially captured at the electrode edges subjected to a strong positive DEP, to form varying cell patterns. Additionally, nanoparticles were used to characterize the ACET-based flow pattern formation. Furthermore, the patterns were successfully exploited as an electrokinetic actuator to actuate continuous droplet switching, fluid mixing and microreactions. Implementing the simultaneous nanoparticle synthesis and guiding demonstrated that the combined field pattern is capable of manipulating both particulate samples and fluids. The proposed micropatterning technique may provide new insights for sample manipulation, on-chip function development and integration with other analytical components (i.e., biochemical sensors, chemical detectors, cell culture bioreactors) owing to a facile operation, easy integration and multifunctionality.