Attension Theta Flex

The Attension Theta Flex is a fully automated optical tensiometer used to characterise surface properties such as contact angle and surface tension between gas, liquid and solid phases.

Attension Theta Flex

The Attension Theta Flex is a fully automated optical tensiometer used to characterise surface properties such as contact angle and surface tension between gas, liquid and solid phases.

Manufacturer Attension
Product Series Theta Optical Tensiometer
Measurement principle Optical tensiometry
Application Surface Tension - Contact Angle
Sample type Chemicals, pharmaceuticals, electronics, foods, energy, paper and packaging
MeasurementsStatic/ dynamic contact angle, surface/ interfacial tension, surface free energy, 3D surface roughness, interfacial rheology

Product Overview

The Attension Theta Flex is a fully automated optical tensiometer used to characterise surface properties and interactions between gas, liquid and solid phases. The method of analysis is to capture the images of a drop of the liquid sample as forms at the end of a syringe. The drop changes shape with time and the sequence of images is analysed to determine contact angle and surface tension.

Measurements are made in air or on a surface. In air the drop is formed at the end of a precision syringe and a camera captures its images. When a drop of sample is placed on a solid surface it spreads and forms a profile that depends on the solid’s surface free energy. The camera captures the image of the drop profile and a fitting method is used to determine contact angle and surface tension. Optical tensiometry measurements are used to determine properties such as: wettability, adhesion, adsorption, cleanliness, heterogeneity, spreading, printability, emulsion and foam stability.

Theta Flex has a motorised stage and dispenser enabling the programming of drop locations on the substrate. There are a range of different types of Drop Profile measurements which are selected to suit the application. A monochromatic cold light source minimises sample evaporation. The high resolution camera accurately records drop profiles and there is fast data transfer to the computer. The modular design means the system is upgradable for future needs.

The OneAttension software provides comprehensive analysis of drop shapes. It uses the Young-Laplace equation as a reference method and can fit the entire drop profile. The user interface enables live analysis and includes a database of liquid properties.

Drop Profile measurements:














Attension Theta Flex received the Red Dot Award for Product Design 2020, and was elected Best of the best in the category of Industrial design making it a winner in the world’s most renowned design competition.

  • Demonstration video
  • Benefits
  • Applications
  • Accessories
  • Theta range comparisons

Demonstration video


One instrument for all needs

  • All the measurements are readily included in the software. Thanks to the modular design, all applications can be fulfilled with one instrument which can be tailored for your needs.
  • Single, double or multi liquid dispenser option for Surface Free Energy analysis
  • Select ready-made experiments or create custom programs.
  • Automatic baseline detection and drop shape fitting
  • Monochromatic cold LED light source for reduced sample evaporation
  • Contact angle on curved surfaces, circular and near-circular.
  • The effect of roughness to wettability can be measured with the unique 3D Topography module.
Make Product Enquiry


  • Contact Angle Measurements on Single Fibres
  • Tensiometry in Inkjet Printing Applications
  • Self-Cleaning Coatings
  • Influence of Contact Angles and Surface Free Energies on Biocompatibility of Biomaterials
  • Wettability of Pharmaceutical Powders
  • Dynamic Contact Angles on Super hydrophobic Surfaces
  • Pulsating Drop Technique to Characterise Surfactant Behaviour in Flotation Process
  • Contact Angle Measurement for Surface Treatment Evaluation in Packaging Industry
  • CO 2 in Enhanced Oil Recovery
  • Comparison of Theta QC and Dyne Pens for Quality Control Applications
  • Contact Angle Measurements in Solar Cell Industry
  • Contact Angle Measurements for Microfluidic Chips
  • Adhesion to Wood-Plastic Composites
  • Influence of Topography and Wettability on Biocompatibility
Make Product Enquiry


3D Topography module

This option enables 3D surface roughness and contact angle to be measured on exactly the same sample location.

The roughness corrected contact angle makes it possible to understand the influence of surface roughness and chemical modification separately on wetting and adhesion properties.

Applications include the biocompatibility of implants and wettability of paper coatings.



Theta High Pressure Chamber

This module enables interfacial tension and contact angle measurements at high pressures and temperatures.

Applications include Enhanced Oil Recovery (EOR) to provide a quantitative measure of wettability in oil reservoirs and to understand the properties of Polymers.



Pulsating Drop module

The module functions by oscillating drops with control of frequency, amplitude and wave shape. This easy measurement of interfacial rheology provides viscoelasticity information for surfactant applications.






Picoliter Dispenser


This allows precision measurements with low volume drops as small as 20 pl. Applications include inkjet printing, printed electronics and contact angle measurement of a picodrop deposited on single fibre.




Tilting Cradle

This tilts the entire Theta and allows automated measurements of dynamic contact angle, used as an indicator of surface homogeneity. Advancing and receding contact angles are measured at the exact moment the drop on the surface starts moving.


Make Product Enquiry

Theta range comparisons

Available measurements Theta Flow Theta Flex Theta Lite
Static contact angle and captive bubble
Batch contact angle
Dynamic contact angle
Menisuc contact angle
Surface/interfacial  tension
3D surface roughness and roughness-corrected contact angle
Interfacial rheology
Surface free energy Zisman Plot, OWRK/Extended Fowkes, van Oss Acid-Base, Wu, Neumann’s Eq. of State, Schultz 1 and 2

Product Enquiry


If you would like to enquire about this product, fill out this form and one of our product specialists will contact you shortly.
If you need help in the operation or repair of an instrument then please contact the Customer Help Centre directly.

Please note, product enquiries are only applicable to Australia, New Zealand, Papua New Guinea and Fiji

    Or call us instead at (02) 9541 3500