Theta Flex Optical Tensiometer


The versatile Theta Flex Optical Tensiometer (also known as a goniometer, contact angle meter & drop shape analyser) allows highly accurate and easy characterisation of both solids and liquids. The instrument offers all measurements in one instrument and is designed for reliable and repeatable measurements of wettability and adhesion, even in the most demanding industrial and research applications.

Theta Flex  is able to perform a complete range of automated or manual measurements which makes it a highly versatile instrument in Research, Industrial and Quality Control laboratories. Measurements include static contact angle with the sessile drop, captive bubble and meniscus methods, dynamic contact angle with the tilted drop and sessile drop methods, surface free energy, surface/interfacial tension with the pendant drop and reverse pendant drop methods, 3D surface roughness with the Fringe projection phase shifting method and interfacial dilatational rheology with the pulsating drop method.

The Theta Flex contact angle meter enables you to choose the level of automation that you require for different applications.  Starting with a basic frame, the versatility of the instrument has a high degree of modularity and an extensive range of accessories that allow you to upgrade or change the instrument as your needs evolve.

The OneAttension software comes with all Theta instruments and combines the most intuitive user interface with a high level of functionality.  Some of its main features include:

  • Best-in-class user interface
  • Superior analysis accuracy
  • Live Analysis
  • Full automation
  • Flexibility for every need
  • Data handling and exporting made easy
  • Optimal for industrial & research use

With optional motorised sample stage, motorised vertical movement and a choice of dispensing systems, Theta Flex can function in a fully automated mode, placing drops in predetermined locations on the substrate and measuring the contact angles.

  • Fully automatic measurements avoids user variation and saves time.
  • Select ready-made experiment recipes or create custom programs for quick and repeatable operations.
  • Automatic base line detection and drop shape fitting.
  • Contact angle on curved surfaces (circular or near-circular).
  • Flexible and programmable frame per second rate recorded by the camera.

For a breakdown on the technical specifications of the complete Theta Flex product range, please click on the Downloads tab below.  Click on the video tab also for an overview of how the instrument works.

ThetaFlex is an advanced optical tensiometer for high accuracy and easy measurement of: –

  • 3D surface roughness – please refer to the downloads section for further information
  • static contact angle
  • dynamic contact angle
  • surface free energy
  • surface tension
  • interfacial tension
  • interfacial rheology
  • wettability
  • absorption
  • adsorption
  • spreading
  • cleanliness
  • surface heterogeneity
Measuring range 0…180°, 0.01…2000 mN/m
Accuracy ± 0.1°, 0.01 mN/m
Maximum sample size W unlimited x 100 mm x 320mm (with stage)
Integrated sample holders Yes
Frame interval 0.33 ms…1000 s
Maximum resolution 1984 x 1264 pixels
Field of view 1.44…32.3mm diagonal
Max. measuring speed 3009 frames/s
Camera USB3 digital camera
Camera protection Inside instrument covers
Camera view angle -4.5….2.5°
Disposable tip dispensing Yes
Light source High power monochromatic LED, 62 x 62mm
Measurement indicator LED Yes
Dimensions H 435 mm, W 230 mm, L 765 mm
Weight (basic frame) 26 Kg
Power supply 90…264 VAC
Frequency 47…440 Hz


Recommended System Requirements:
2GHz processor, 2GB RAM, 120 GM hard disk drive*, 1920 x 1080 resolution, 1 USB3 port,  1 additional USB3 port required with 3D topography module.

* SDD hard disk (min. 500 MB/s) needed for high speed recording with high resolution.

Operating System Requirements:
Windows 7 & 8 & 10 (32 or 64 bit).



Contact our Sales Team directly to discuss your individual requirements.  See typical configurations below & refer to the product brochure.
           Dispenser      Droplet placement      Sample stage
Theta Flex Auto 5           Auto, 4 liquids           Auto           Auto XYZ
Theta Flex Auto 4           Auto, 2 liquids           Auto           Auto XYZ
Theta Flex Auto 3           Auto, 1 liquid           Auto           Auto XYZ
Theta Flex Auto 2          Auto, 2 liquids           Auto           Auto X, Manual YZ
Theta Flex Auto 1           Auto, 1 liquid           Auto           Manual XYZ
Theta Flex Plus           Auto , 1 liquid           Manual           Manual XYZ
Theta Flex Basic           Manual           Manual           Manual XYZ



Complement your system with the additional modules that will enable further capabilities:

  • 3D Topography Module: Roughness-corrected contact angle measurements automatically with a single click.  For studying the effect of surface roughness to contact angle results.
  • High Pressure Chamber: Enables measurements at pressures up to 400 bars and temperatures up to 200°C.  Designed for enhanced oil recovery and super-critical fluid applications.
  • Pulsating Drop Module – PD 200: Oscillates drop volume for interfacial rheology studies.
  • Tilting Cradle: For fully automatic dynamic contact angle and roll-off angle measurements by the tilted drop method.
  • Environmental Chambers: To control the measurement environment including the temperature.

Please contact our sales team to discuss your individual requirements.