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High Accuracy Flow Meter for Low Flow Measurements

With the growing popularity of micro-bioreactors, perfusion, as well as cell & gene therapy applications in the life sciences industry, the need to measure low flow rates non-invasively is ever increasing. The new SONOFLOW CO.55 V3.0 non-contact clamp-on flow meter pushes the boundaries of low flow measurement in flexible tubing.

During the development of the SONOFLOW CO.55 V3.0 flow meter, SONOTEC focused on major requirements in the biotech industry that cover low flow applications in process development, cell & gene therapy, as well as accurate dosing of biopharmaceuticals. With the new sensor generation, SONOTEC offers outstanding measurement accuracy combined with excellent clamp-to-clamp repeatability. Designed to increase efficiency and reproducibility in PAT-related bioprocessing, real-time data availability makes the sensor also ideally suited for process modelling.

As a critical process parameter (CPP) the flow volume of the medium can affect critical quality attributes (CQAs), which are defined to ensure the desired product quality. Even minor deviations in the flow velocity or flow volume might have an effect on the cell growth. Thus, it is essential to measure the liquid flow in all process steps. Monitoring and validating real-time flow data throughout the entire production can substantially improve process stability.


In order to demonstrate the low flow capabilities of the new SONOFLOW CO.55 V3.0 flow meter series, the ultrasonic specialist SONOTEC performed a number of comparative measurements between a SONOFLOW CO.55 V2.0 and SONOFLOW CO.55 V3.0 sensor. For the testing, water (@ 23 °C) was pumped through a ¼” (OD) tubing using a peristaltic pump or a syringe pump, which are both connected via a Y-connector to the measuring tubing. Each pump can be pinched off using standard hose clamps. Both flow meters are clamped to a new, straight line of tubing with a distance of exact 20 cm before, between, and after the sensors. For accurate reference measurement, the scale does not have any contact with the setup material and is tared before each test run.

The plot summarizes the results by focusing on the flow range between 2.5… 100 mL/min. At flow rates higher than 50 mL/min, both non-contact clamp-on flow meters show almost the same deviation from the target flow with an accuracy of 1 % and better.