Fiber Optic Assisted Optofluidic Viscometer for Biomedical Applications

Optical fiber technology is gaining increasing importance in all those fields requiring reliable, miniaturized, compact, and plug-and-play devices, with a special relevance in life science applications. Here, optical fibers are adopted to measure the fluids viscosity, by detecting the transit time (related to viscosity) of a steel bead moving through the tested fluid in a microfluidic channel under constant pressure. The proposed optofluidic system is designed by defining a theoretical model, here experimentally validated in the viscosity range of 5–110 cP, well resembling main blood flow features. The achieved results demonstrate the capability to work in multi-point and single-point detection modalities with a trade-off between resolution (minimum of 10−1 and 1 cP respectively) and measurement time (tens of seconds and milliseconds range, respectively). An optimum accuracy close to 1.5% has been achieved, with room for further optimization by reducing bead size uncertainty. The proposed platform features simple, low-cost, reliable, and fast measurements and ensures the integration with microfluidics chip in a miniaturized and disposable system. The low volumes required (scalable down to µL range) and the ease of use enable the translation of the proposed platform in clinical scenarios involving real-time blood and plasma viscosity measurements under physiological conditions.