Long-term digital microfluidic chips for regulating macrophage cellular interactions in inflammation.

We introduce a robust multilayer dielectric stack for digital microfluidic chips to withstand the humid conditions of cell culture incubators for at least 60 days. Consisting of a combination of 1 μm polyvinylidene difluoride and 5 μm SU-8 layers, the stack demonstrated high breakdown voltages up to 1600 V and minimal surface currents <30 nA at 100 V. Long-term stability and precision in liquid handling enabled us to study macrophage phenotype modulation, pro-inflammatory response induction in macrophage population with single cell cytokine quantification and testing of a potentially anti-inflammatory drug candidate TCB-2 and its influence on macrophage phenotype, morphology, and cytokine release. The multilayer dielectric stack offers a durable solution for long-term biological assays on digital microfluidic platforms.