What you can measure

  • Static contact angle 
    Sessile drop, captive bubble and meniscus methods
  • Dynamic contact angle 
    Dynamic contact angle, advancing and receding contact angle, contact angle hysteresis and roll-off angle
  • Surface free energy 
    Sessile drop, captive bubble and meniscus methods
  • Surface- and interfacial tension 
    Pendant drop and reverse pendant drop methods
  • Roughness-corrected contact angle and 3D surface roughness 
    Fringe projection phase shifting method
  • Interfacial dilatational rheology
    ulsating drop method

3 reasons to invest

One instrument for all your needs

Flexible at its core, this instrument gives you plenty of measuring possibilities. All neatly packed in our easy-to-use software. Add accessories and modules to match your needs. 

Results you can trust

We know that high quality imaging is essential for high quality results. Therefore the Theta Flex camera has a resolution of 1984 × 1264 px with a maximum of 3009 FPS. Sophisticated algorithms record and analyze the contact angle and surface free energy for you, and you can follow the experiment in real-time. 

Need for speed?

All steps of your measurements can be automated to speed things up in the lab. This way you can also avoid user dependency. The outcome will be more precise, and experimenting more smooth. Enjoy. 


Not sure which tensiometer you need?

Use InstruMentor to find and customize your optimal instrument.

InstruMentor – Tensiometer selector


A closer look

Check out the specifics of Theta Flex and compare it to our Theta Lite to find out what you need. Theta Flex systems come in ready-made packages optimized for your automation level. Other packages can also be formed easily thanks to the modular design.

Theta Flex
Theta Lite

Available Measurements

Static contact angle
Dynamic contact angle
Automatic Manual
Surface/Interfacial tension
3D surface roughness
Interfacial rheology
Surface free energy
Zisman Plot, OWRK/Extended Fowkes, van Oss Acid-Base, Wu, Neumann’s Equation of State, Schultz 1 and 2

Available Measurement Methods

Sessile drop
Batch sessile drop
Captive bubble
Pendant drop
Reverse pendant drop
Dynamic contact angle
Automatic Manual
Pulsating drop
3D Topography


Measuring range (°, mN/m)
0…180, 0.01…2000 0…180, 0.01…2000
Accuracy (°, mN/m)
±0.1, ±0.01 ±0.1, ±0.01
Maximum sample size (mm)
Unlimited×100×320 (with stage) Unlimited×45×200 (with stage)
Integrated sample holders
Yes Yes
Frame interval
0.33 ms ... 1000 s 0.48 ms ... 1000 s
Maximum resolution (px)
1984×1264 1280×1024
Maximum measuring speed (fps)
3009 2068
USB 3.0 digital camera with zoom USB 3.0 digital camera
Camera protection
Inside instrument covers Inside instrument covers
Camera view angle (°)
 -4.5 ... 2.5  -2 ... 2
Light source and size
LED based background lighting, 62 x 62 mm LED based background lighting, Ø 20 mm
Field of view (Ø, mm)
1.44…32.3 2.9…12 
Measurement indicator LED
Yes No
Disposable tip dispensing
Dimensions — Basic frame (L×W×H, mm)
 765 x 230 x 435  495 x 130 x 310
Weight — Basic frame (kg)
26 5
Power supply (VAC)
90…264 100…240
Frequency (Hz)
47 ... 440 50 ... 60
Droplet placement
Sample stage
Possible upgrades
Theta Flex Auto 5
Auto, 4 liquids Auto Auto XYZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Auto 4
Auto, 2 liquids Auto Auto XYZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Auto 3
Auto, 1 liquid Auto Auto XYZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Auto 2
Auto, 2 liquids Auto Auto X, Manual YZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Auto 1 
Auto, 1 liquid Auto Manual XYZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Plus
Auto, 1 liquid Manual Manual XYZ 1984 × 1264 px, max 3009 FPS Full
Theta Flex Basic
Manual Manual Manual XYZ 1984 × 1264 px,  max 3009 FPS Full
Theta Lite Auto 2  
Auto, 2 liquids Manual Manual YZ 1280 x 1024 px,  max 2068 FPS Limited
Theta Lite Auto 1  
Auto, 1 liquid Manual Manual YZ 1280 x 1024 px,  max 2068 FPS Limited
Theta Lite Basic
Manual Manual Manual YZ

1280 x 1024 px, max 2068 FPS



OneAttension Software

We made our software for Theta Flex with you in mind. It is a fine combination of a very intuitive interface and high functionality. Follow your experiment live, and get the results within seconds. OneAttension is analyzing made easy. Let's have a look at the features! 


OneAttension Features

  • User friendly interface
    To get you going in no time
  • Fully automated measurements
    Saving your time and avoiding user dependency
  • Automatic baseline detection and drop shape fitting
    For simplicity and precision
  • Batch angle mode
    When you have plenty of tests to run in no time
  • Meniscus contact angle mode
    When you are finding out the contact angle of fibers
  • Automated liquid purity checkup
    So you can trust your results
  • Fully automatic dynamic contact angle mode with the needle method
    For user-independent results



Add more possibilities

With the modular design and an extensive range of modules and accessories you have room to upgrade or change the Attension Theta Flex as your needs evolve. Have a look at a few selected examples or explore the full range below.


Topography 3D module

Theta Flex can be combined with the unique 3D Topography module that takes the wettability and adhesion analysis into a completely new level by measuring both contact angle and surface roughness of the sample in a single measurement. Distinguish the effect of roughness on contact angle and surface free energy.


High Pressure Chamber

The High Pressure Chamber is designed for wettability research within enhanced oil recovery and enables measurements at pressures up to 400 bars and temperatures up to 200°C. Integrated chamber piston and sample port are optimized for the best usability and versatility.


Tilting cradle

A software controlled tilting cradle. Used for studying dynamic contact angles. Tilting range from 0 to 90° and tilting resolution 0.1°. The vacuum stage top C204B is recommended to be used with this option.


Pulsating Drop Module - PD200

Software controlled drop size pulsing for interfacial rheology measurement of viscoelastic properties of interfacial layers at liquid-air or liquid-liquid interfaces. 


Picoliter Dispenser

Automated picoliter-scale drop formation. Especially for inkjet applications and for measuring contact angle on very small sample areas.


What others say

Our instruments are present at many prestigious universities and research facilities world wide. Take a minute to find out what others say about Theta Flex. 



Ville Jokinen. Aalto University

"The ability to measure the advancing and receding contact angles with a single click and having the data into a convenient format saves time and reduces the human error."

Watch the full story



Aalto University, Finland

Aalto University is a top Finnish university combining science, technology and arts into a collaborative environment for both scientific communities and companies. Our contact angle meters and tensiometers have been used there in research for decades. 




Researcher at MIT

“The reproducibility of the measurements acquired is excellent even with the lowest surface energy values and the tensiometers are quite flexible with regards to sample size. The software is also very useful and the customer support for the products is excellent.”



MIT, Massachusetts Institute of Technology, is a world-leading research university with a mission to advance knowledge and educate students in science and technology. MIT use our tensiometers to study contact angles and interfacial energy.