An addressable electrowetting valve for centrifugal microfluidics

Centrifugal microfluidic platforms aim to integrate and perform complex biological and chemical processes within disc-like substrates and valving through centrifugal forces and the Coriolis effect. Although the integration of active valves within such system can be used to enhance fluid control, the ability to fabricate and integrate addressable valves within centrifugal platforms remains a significant challenge. To address this issue, herein, we present and test an addressable electrowetting centrifugal (EWC) valve. The EWC valve comprises a hydrophobic burst valve, integrated side electrodes and a dielectric layer between the microfluidic channel and electrode structures. The burst valve is made from a hydrophobic material able hold a specified pressure. Specifically, application of an external electric field is used to alter the valve wettability, making the valve more hydrophilic, decreasing the threshold pressure and triggering the opening of the valve. To assess valve performance, we investigate the influence of electric properties and channel geometry on valve response and then demonstrate multiple operations on different fluid samples. Finally, and to highlight the utility of EWC valves, we demonstrate the detection and analysis of CD4 human immune cells.