Universal Pre-Mixing Dry-Film Stickers Capable of Retrofitting Existing Microfluidics

Abstract

Integrating microfluidic mixers into lab-on-a-chip devices remains challenging yet important for numerous applications including dilutions, extractions, addition of reagents or drugs, and particle synthesis. High efficiency mixers utilize large or intricate geometries that are difficult to manufacture and co-implement with other lab-on-a-chip processes, leading to cumbersome two-chip solutions. To that end, we present a universal dry-film microfluidic mixing sticker that can retrofit pre-existing microfluidics and maintain high mixing performance over a range of flow rates and input component mixing ratio. To attach our pre-mixing sticker add-on module, one simply removes the backing material and presses the microfluidic sticker onto an existing microfluidic or substrate. Our key innovation centers around the multilayer use of laser-cut commercially available silicone-adhesive coated polymer sheets as microfluidic layers to create geometrically complex yet easy to assemble designs that can be adhered to a variety of surfaces, namely existing microfluidic devices. Our approach enabled us to assemble the well regarded yet difficult to manufacture “F-mixer” in minutes, and conceptually extend this design to create a novel space-saving spiral F-mixer. Computational Fluid Dynamic simulations and experimental results confirmed that both designs maintained high performance for 0.1<Re<10, and disparate input mixing ratios of 1:10. We then tested the integration of our system by using the pre-mixer to aid in the fluorescent tagging of proteins encapsulated in an existing microfluidic. When integrated with another microfluidic our pre-mixing sticker successfully combined primary and secondary antibodies to fluorescently tag micropatterned proteins with high spatial uniformity, unlike a traditional pre-mixing “T-mixer” sticker. Given the ease of this technology, we anticipate numerous applications for point of care devices, microphysiological-systems-on-a-chip, and microfluidic based biomedical research.