Digital microfluidics (DMF) takes advantage of the electrowetting-on-dielectric (EWOD) phenomenon to independently manipulate discrete droplets (pico- to microliter) using an arrayed platform of interdigitated electrodes. Recent advances in DMF have enabled the miniaturization and automation of chemical and biochemical laboratory processes. However, there are surprisingly few reports on the EWOD behavior and DMF applications of nanofluids (i.e. engineered colloidal suspensions of nanometer sized particles), and reports of quantum dot (QD) nanofluids within such a platform are almost nonexistent. QDs have unique optoelectronic properties that arise from the confinement energy of the semiconductor nanocrystal, and have been utilized in cell labeling, displays, and photovoltaics. Herein, we report on the fundamental electowetting behavior of polymer-encapsulated CdSe/ZnS QD nanofluids and explore their utility within a DMF platform. The stability and performance of electrically modulated QD nanofluid droplets are investigated by varying the amphiphilic solubilizing polymer, altering the size of the QDs, and the addition of surfactants to the ambient, non-conducting medium. Optimized nanofluids are subsequently utilized within an open-source DMF platform—OpenDrop V3—to demonstrate the ability to quickly and efficiently manipulate small volumes of fluorescent liquids via an externally applied voltage. The speed of the droplets is dependent upon the voltage and surfactant employed, and the ability to mix fluids with different emissions to result in new optical properties is also presented.

Digital microfluidic applications of polymer-encapsulated quantum dot nanofluids

2019 Spring National Meeting

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