Real time nanoflow metrology paper published in Measurement: Sensors

I'm excited to announce the publication of our new paper on the optofluidic flow meter we developed at NIST that achieves unprecedented accuracy and dynamic measurement capabilities for extremely low fluid flows - down to just 1 nanoliter per minute. Our work addresses a critical need in the growing field of microfluidics. As these systems become more sophisticated and widely used in medical diagnostics, manufacturing, and research, the ability to precisely measure and control tiny amounts of fluid becomes increasingly important.

The image below illustrates the flow meter's basic principle of operation. Fluid containing a fluorescent chemical flows through a microchannel and is hit with laser light. The lower the flow rate, the more time fluorescent molecules spend absorbing laser light, and the more likely they are to photobleach. This allows us to directly determine the flow rate from the amount of fluorescence detected.

In this work, we used our recently developed optofluidic flow meter to study the performance of commercial syringe pumps and thermal flow meters in the sub-microliter-per-minute regime. By comparing measurements across different instruments, we demonstrated that our system provides superior accuracy and dynamic measurement capabilities. Notably, we found that many commercial pumps exhibit larger flow variations than their specifications suggest - information that was previously difficult to obtain at these scales. The figure below shows a representative measurement of the flow generated by a syringe pump set to 25 nL/min using our optofluidic flow meter as well as two popular commercial flow meters.

The paper, titled "Accuracy and dynamics of flow measurements to 1 NL/min using an optofluidic flow meter," appears in the journal Measurement: Sensors.