Simple, low-cost styrene-ethylene/butylene-styrene microdevices for electrokinetic applications.

Styrene-ethylene/butylene-styrene (SEBS) copolymers combine thermoplastic and elastomeric properties to provide microdevices with the advantageous properties of hard thermoplastics and ease of fabrication similar to PDMS. This work describes the electrical surface properties of SEBS block copolymers using current monitoring experiments to determine zeta potential. We show that SEBS exhibits a stable and relatively high zeta potential magnitude compared to similar polymers. The zeta potential of SEBS is stable when stored in air over time, and no significant differences are observed between different batches and devices, demonstrating reproducibility of results. We show zeta potential trends for varying pH and counterion concentration and demonstrate that SEBS has a repeatable surface potential comparable to glass. Oxygen plasma treatment greatly increases the zeta potential magnitude immediately following treatment before undergoing a moderate hydrophobic recovery to a stable zeta potential. SEBS copolymers also offer simple rapid prototyping fabrication and mass production potential. The presented electrokinetic properties combined with simple, low-cost fabrication of microdevices make SEBS a quality material for electrokinetic research and application development.