Controlled Massive Encapsulation via Tandem Step Emulsification in Glass

Controlled encapsulation is important in pharmaceutics, agriculture, food products, and in emerging materials applications. Microfluidics offers a compelling approach to create controlled emulsions and microcapsules for these applications, but upscaling of this technology for the robust encapsulation of chemically diverse active ingredients is not yet demonstrated. Here, it is shown that microfluidic step emulsification can be exploited in upscaled glass devices to robustly produce monodisperse double emulsions and functional microcapsules in tandem at high throughput rates. The effect of geometrical parameters of the devices and the operating flow rates on the morphology, dimensions, and structure of monodisperse double emulsions is investigated and quantified using simple quantitative models. Using such double emulsions as templates, mechanoresponsive microcapsules that can be embedded in a soft matrix to generate damage‐reporting polymer parts that change color in areas subjected to excessive mechanical loads are created. Thanks to the chemical versatility and mechanical robustness of glass, this platform should enable the high‐throughput encapsulation of a wide variety of chemicals while providing the exquisite control achievable through microfluidics. Tandem step emulsifiers produce monodisperse capsules with size‐controlled inner and outer phases at high through‐put rates. The double emulsions are tailored by the flow rate and the geometry of the microfluidic device. Combined with the chemical versatility of glass, these devices allow for the encapsulation of a wide variety of chemicals with exquisite control over the emulsion structure.