Digital microfluidics (DMF) for SERS analysis on a chip with EWOD-/(w)OEW-actuated analyte droplets

• Applicants: Professor Dr. Detlev Belder; Professor Dr. Henning Fouckhardt
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 366065598

Electrically conducting fluid droplets can be actuated via electrowetting on dielectric (EWOD) and opto-electrowetting (OEW). In principle, the OEW control lightwave might even be waveguided within the layer sequence beneath the droplet (idea Fouckhardt, waveguide-based OEW = wOEW). An important application is represented by droplet manipulation in digital microfluidics (DMF, lab on a chip 2.0) in chemical chip-sized laboratories.An obstacle for a break-through of digital microfluidics in miniaturized chemistry is given by a lack of sensitive, non-destructive methods for detection, allowing for the doubtless identification of chemical substances in discrete droplets on a DMF chip. In the project proposed here surface-enhanced Raman scattering or spectroscopy (SERS) shall be employed for this purpose on a chip for the first time (idea Belder), which shall make well evaluable vibrational spectra possible. By the interaction of the analyte molecules (within the droplets) e. g. with metallic nanoparticles dispersed in the droplets high signal amplifications should be obtainable.The undertaking is aimed at the first-time combination of DMF and SERS and the concurrent droplet actuation by EWOD-OEW-wOEW. By the optical initiation of the droplet movement new opportunities for the realization of unpretentious lab on a chip systems should arise.The cooperation of the groups Belder and Fouckhardt should provide for synergies, which make a break-through of the DMF technology in the context of chemical lab-chips possible. The Belder group focuses on SERS detection within DMF systems. The Fouckhardt group concentrates on further development of droplet actuation via EWOD and OEW, preferably up to wOEW.Moreover, in close cooperation the potential of solid metallic SERS targets is to be investigated, which might simultaneously be used as electrical contacts or mirror layers for the EWOD-(w)OEW technologies. Multifunctionality of components is to be considered as inherently positive for further miniaturization of DMF lab chips.In principle, for any of the SERS target alternatives any of the mentioned actuation variants, i. e. EWOD, OEW, or wOEW, might be used. The (preliminary) allocation in the work program is owed to the temporal coordination of work packages of both groups.In case of need, for droplet actuation OEW (compared with wOEW) or even EWOD (compared with wOEW and OEW) might act as a fall-back position. Even the combination of DMF and SERS and EWOD actuation would be new.

• DFG Programme: Research Grants