Measuring low viscosity fluids with the Fluidicam Rheo

FluidicamRheo2

Introduction

Analyzing low viscosity liquid products such as vaccines or water-based formulations can be a challange for traditional techniques like rotational rheology.
The Fluidicam technology allows for fast and precise measurements of even viscosity products with minimal sample volume.

Reminder on the technique

FLUIDICAM RHEO uses a co-flow microfluidic principle to measure viscosity of various products. A sample and viscosity standard are introduced together in the microfluidic channel (typically 2.2mm X 150µm) where they undergo strong confinement. Applied shear rate is adjusted by a computer-controlled syringe pump. Under these conditions, the interface position between the two fluids is related to the viscosity ratio between them. Images of the resulting laminar flow are acquired with to an integrated camera and the viscosity of the sample is automatically calculated as a function of shear rate and plotted directly in the software giving a resulting viscosity curve.

microfluidics 

Experimental results

Water, ethanol and methanol were analyzed at 25°C using a mechanical rheometer and with FLUIDICAM (Fig 1). At shear rates below 10 s-1
rheometer measurements oscillate to negative values. Above 100s-1 the Taylor-Couette instability can be noticed. On the other hand,
samples run with FLUIDICAM present expected Newtonian behavior and can be easily distinguished from one another.

curve1

The measured viscosities were compared to documented values. Fig 2. summarizes mean viscosity values in cP for both techniques.
Both instruments present a good agreement with theoretical values,
however FLUIDICAM offers higher precision compared to the rotational rheometer

curve2

Conclusion

FLUIDICAM RHEO allows fast and easy viscosity measurements in less than 4 minutes per sample
(compared to 25 min using rotational rheometer). The use of microfluidic principles offers good precision
even at low viscosity and minimal sample volume.

Key Benefits

Precise – measurement in a co flow with a reference solution 
Small sample volume - less than 1ml minimum sample volume
Quick – Less than 4 min per viscosity curve

channel

 

PRECISE – measurement in a co flow with a reference solution