A 3D printed flow sensor for microfluidic applications

Here, we describe the development and characterisation of a flow sensor for microfluidic applications. The flow sensor utilises two miniaturised commercial pressure sensors mounted across a 3D printed microfluidic tube to measure the flow rate based on the viscous pressure drop occurring between the two sensors. The operational range of the flow sensor can be modulated by varying the diameter of the microfluidic tube. We demonstrate the suitability of the flow sensor for measuring constant and dynamic flow rates driven by syringe, piezoelectric, and pressure pumps. We characterise the flow sensor against water, water-glycerol solutions, and human blood. We harness the sensitivity of the sensor for measuring the viscosity of human blood at physiologic and room temperatures. We also show the ability of the flow sensor for monitoring the transitory flow rates generated by a manual pipette. The flow sensor is compact, low-cost, and highly responsive. It has no moving elements and can be easily tailored, interfaced, and operated. These features make it appealing for a wide range of applications in microfluidics.