In-Channel electrowetting technology for lab-on-chip applications

Electrowetting-on-dielectric (EWOD) is a versatile tool in lab-on-chip systems since it controls fluid shape and flow by electrical signals alone without using external pumps and related tube connections. The most versatile EWOD configuration (allowing transport, division and mixing of droplets) is the closed one, where the fluid handling occurs between two coupled glasses. However, the use of EWOD-based lab-on-chip is often laborious due to the necessity of spacers between the bottom and top glasses as well as of oil to confine the solution droplets and to avoid fluid evaporation. In order to overcome these issues, we have developed a new technology called In-Channel EWOD (ICEWOD) relying on the microelectronic definition of the microfluidic channel in the top glass and on the microelectronic fabrication of the EWOD electrodes in the bottom glass. Experiments, performed injecting a saline solution in the reservoir (see Figure 2c), demonstrated both the successful dispensing of separate droplets from the reservoir and their subsequent movement along the electrodes to fill the central chamber. Furthermore, the system showed robustness against mechanical stress as well as high reliability after several tests.