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 SeriesTheta Optical Tensiometer
Measurement principleOptical tensiometry
ApplicationSurface Tension - Contact Angle
Sample typeChemicals, 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 8 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.

Theta Lite is a cost-effective version of the Theta with 6 Drop Profile measurements and a manual sample stage and manual or automated liquid dispenser.

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 and the instrument 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 base line 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.
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  • 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 Characterize 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
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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.


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Available Measurements
Static contact angle
Dynamic contact angleAutomaticAutomatic
Surface/Interfacial tension
3D surface roughness
Interfacial rheology
Surface free energy (SFE)
Available Measurement Methods
Sessile drop
Captive bubble
Pendant drop
Reverse pendant drop
Pulsating drop
High pressure
3D Topography

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Product Enquiry

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