Flow-through Permittivity Sensor


Flow-through Permittivity Sensor


Flow-through Permittivity Sensor

Liquid Permittivity (Dielectric) Sensing for a wide range of applications

The FPS is useful as a sensor/detector for research and development, QA/QC testing, automation and diagnostics of scientific instrumentation and liquid dispensing/handling devices. Here are a few of our favorite applications:

Liquid Chromatography Gradient Monitoring

Permittivity is a useful measure for monitoring gradients produced by LC pumps. When reproducibility is important, an FPS placed between the gradient pump and column provides assurance and a record of the gradient. Pump and solvent issues can be detected immediately.

CCC/CPC Multi-phase Liquid Monitoring

Monitoring the biphasic eluant as it exits the CCC column provides a new level of insight on stationary phase retention and bleed in real-time. Eliminates human error and tedious manual measurements. The 1kHz data-rate allows the FPS to be used for volumetric metering of multi-phase systems -- this means real-time Sf and K.

Process/System Control and Automation

The FPS is an excellent choice for detecting both gradual and instantaneous changes to flowing liquids. It's also useful for single and multiphase liquids and works great for bubble detection.


Total Internal Volume: 45µL

Measurment Cell Volume: 20µL

Wetted Materials: 316 SS, Borosilicate, ETFE

Fluid Connections: 10-32F (1/16” tubing)

Max pressure: 4000psi

Max flow (recommended): 100mL/min

Ambient Operating Temperature: 10~30°C

Temperature Sensor Range: -40~110°C

Data/Power Port: USB-C

Sampling Rate: 1kHz

Avg. Resolution 1-80 εr(k): ~0.03

Enclosure: 89.9x36.1x30.0mm Aluminium

What is permittivity?

Permittivity is a measure of how resistant something is (liquid in our case) to an electrical field. It's typically measured as "relative permittivity" (εr), or "dielectric constant" (k), and is an effective measure of chemical polarity. By definition a perfect vacuum has a relative permittivity of exactly 1, while water has a very high measure of ~80; most other liquids fall within this range.

The output signal of the FPS relates directly to the relative permittivity of the liquid flowing through it. It's also important to note that temperature effects permittivity, which is why the FPS has a integrated temperature sensor to correct for temperature fluctuations in harsh environments and sensitive applications.

The raw FPS Signal is an inverse log of the liquid's relative permittivity, and once calibrated can be transformed directly to relative permittivity as shown below.


Features and Options

Easy to use with simple protocol and USB interface

Custom materials and flow-rates available

Integrated temperature sensor

Highly inert flow path and capable of high pressure

Built to withstand hard chemical environments


For more information, quotations, or orders please contact us at We'll typically get back to you within 24 hours.