Viscosity measurements utilizing a fast-flow microfluidic paper-based device

Abstract

Traditional microfluidic paper-based analytical devices (μPADs) use capillary action to transport fluids through a single layer of paper. While μPADs have many advantages, flow rates are typically quite slow. Fast-flow paper-based analytical devices (ffPADs) have unique and advantageous flow characteristics that differ from traditional μPADs. ffPADs have a hollow channel with paper on at least one side that generates flow rates of cm/s. Within the device, two types of flow interact with each other to create the fast flow phenomenon. In this work, we take advantage of these flow characteristics to create a viscosity measurement method for biofluids. Solution viscosity is important for a range processes from pharmaceutical formulations to clinical diagnostics. The proposed method uses a small sample volume (100 μL) without the need for reference fluids or measurements for unknown fluid properties. Additionally, the device is fabricated from paper, double-sided adhesive and transparency film, so it still possesses the advantages of traditional paper-based devices such as portability, ease of use, and low-cost. To confirm the device performance, viscosities of polyethylene glycol (PEG) solutions were measured at different concentrations and were found to be in good agreement with a commercial viscometer. Finally, viscosity measurements of artificial saliva solutions were also demonstrated to verify biofluid applicability.