Online Micro Dilution Module

The Online Micro Dilution Module (OMD) extends the NanoFlowSizer for applications in which particle concentrations are too high for direct measurement under representative process conditions.

By continuously extracting a small sample stream and diluting it under controlled conditions before analysis, the OMD supports reliable real-time particle size monitoring in challenging process environments.

This makes the OMD especially relevant for workflows involving highly concentrated nanosuspensions, complex rheology, or strong particle-particle interactions.

Direct measurement at very high concentrations can be challenging

The NanoFlowSizer can measure highly turbid suspensions without dilution. However, at very high particle concentrations, sample behavior can become more complex.

Increased viscosity and particle-particle interactions may influence diffusion behavior and affect direct particle size interpretation.

Controlled dilution supports robust measurement

The OMD module addresses this by continuously extracting and diluting the sample before measurement.

This creates more suitable measurement conditions while preserving the value of real-time process monitoring.

Instead of relying on manual sampling and offline dilution, users can follow particle size continuously during processing.

The OMD module typically extracts between 10 and 150 µL/min from the process stream and dilutes the sample with a suitable diluent before measurement.

A common operating point is an extraction rate of 50 µL/min combined with approximately 50x dilution.

Under these conditions, one hour of continuous measurement results in only about 3 mL of product waste, while using approximately 150 mL of diluent.

After extraction from the process, the sample is diluted and mixed through a static mixer before entering the measurement flow cell.

At typical diluent flow rates, the delay between sampling and measurement is generally in the range of 1 to 2 minutes.

Real-time monitoring during milling

One process area where the OMD module is especially valuable is wet bead milling.

In these workflows, larger particles are reduced to the nanoscale, often in suspensions with solid fractions that are too high for convenient direct real-time measurement.

By combining the NanoFlowSizer with the OMD module, users can monitor particle size distribution continuously during milling and follow how the suspension evolves over time.

Better insight into process progression

At the start of milling, particle sizes and distributions are typically broader and larger.

As the process progresses, particle size decreases and the distribution narrows toward the desired endpoint.

The OMD module helps users observe these trends in real time and determine more precisely when endpoint criteria have been reached.

Support for process understanding and endpoint decisions

Continuous access to parameters such as z-average, PDI, and D90 supports improved process understanding.

It can also reduce uncertainty in late-stage milling and create a stronger basis for process control and endpoint decisions.

At the start of the wet bead milling process, larger particle sizes and broader particle size distributions (PSD) are observed. At the end of the process, particle size and PSD are smaller and have reached the endpoint specification.

Fits within a modular NanoFlowSizer setup

The OMD module is part of the NanoFlowSizer accessories portfolio. It allows users to configure the system for sample conditions where controlled online dilution is needed for robust measurement performance.
This modular approach helps align the measurement setup with the specific demands of the process.

Discuss your process setup with our team

Looking to monitor highly concentrated nanosuspensions in real time?

We can help determine whether the OMD module fits your workflow, process conditions, and integration requirements.