Microstructured Multimaterial Fibers for Microfluidic Sensing

The thermal drawing of a uniform capillary-like fiber that integrates an encapsulated microchannel and an embedded capacitor system within a polymeric cladding is demonstrated. Such a fiber construct has versatile functionalities applicable to microfluidic sensing including the detection of the presence and travel distance of a fluid, real-time flowrate sensing, and high-accuracy identification of the static dielectric constant, which reveals information on the nature of the fluid inside the channel. As a capacitive device, the fiber exhibits a broad operative frequency range from 100 Hz to 2 MHz, and is capable of sensing microflows with a wide flowrate range from 50 nL min(-1) to 10 mL min(-1). Beyond such performance, the novel fabrication approach proposed, based on fiber processing, is highly scalable and can potentially yield tens-of-kilometers of such fibers in a single draw, equating millions of short (few centimeters) working capillaries. It offers significant opportunities for reliable monitoring and manipulation of complex microfluidics, especially in cases requiring flexible and disposable sensors, at a scalability and cost traditionally associated with fiber processing technologies.