Droplet Platform for Actuation and Chemical Mixing of Multiple Droplets

An open microfluidic system has been developed to dispense and manipulate individual droplets on plastic sheets. Superhydrophobic material is applied to the surface of obtainable plastic sheets by spraying, then hydrophilic symbols are printed with an inkjet printer. The plastic sheets are connected to a two-axis tilting platform driven by stepper motors, which produces mechanical agitation enabling droplet transport. The system has been demonstrated to carry out various droplet operations, such as moving droplets of different sizes, transporting multiple droplets concurrently, fusing and combining multiple droplets, dispensing small droplets from a large droplet or liquid reservoir, and one-directional droplet transportation. As a proof-of-concept, a colorimetric assay has been implemented to measure glucose concentration in sheep serum. In comparison to silicon-based digital microfluidic systems, this system is especially suitable for biological experiments due to its ease of changing designing layouts of hydrophilic symbols, quicker turnaround time in printing on plastic sheets, larger area to accommodate more tests, and lower operational costs through the use of off-the-shelf products.