Surface tension/interfacial tension is a crucial parameter, relating to the wettability (contact angle) and adhesion of a liquid to a solid surface. It influences many processes, such as cleaning, foaming, emulsification, etc., and product stability. In most cases, it's necessary not only to understand the quasi-static value of surface tension/interfacial tension but, more importantly, to analyze and grasp its dynamic variation characteristics.

Common surface tension/interfacial tension measurement methods can be categorized into three types based on their measurement principles：

    (1) Force surface tension meters using force sensors, such as the plate/ring method；

    (2) Surface tension meters using pressure sensors, such as the maximum bubble pressure method (MBPM)；

    (3) Droplet/liquid surface profile analysis methods, such as the pendant drop profile analysis method (PDA). The droplet volume method (DVT) should also be classified into the third category, as it is essentially based on droplets and their stability.

The DropMeter DOT series surface tension meters are a new generation of measurement methods based on the Type III principle. They can simultaneously be equipped with the following three dynamic surface/interface tension (IFT) measurement methods：

    a) (Fully-automated) Pendant Drop Analysis (haPDA)；

    b) (Fully-automated) Drop Volume Tensiometry (DVT)；

    c) (Fully-automated) Maximum Drop Volume Tensiometry (MDVT).

All three methods can be used simultaneously to measure the same liquid/flow interface!

Features of Three Dynamic Surface/Interfacial Tension (IFT) Measurement Methods

haPDA Fully Automated Drip Profilometry Dynamic IFT Measurement

    ● Supports sinking droplets, rising droplets, and rising bubbles.

    ● Measurement lower limit approximately 0.01 mN/m, resolution ±0.01 mN/m or 0.01%, accuracy error <0.1%.

    ● Can measure dynamic surface/interfacial tension from 200 ms onwards.

    ● Offers Static/Dynamic/Dynamic-Ex and custom modes, fully automated throughout the entire process.

    ● Supports constant volume/surface area mode and droplet locking, ensuring stable and reliable measurements.

    ● Features intelligent guidance and error detection, improving operational accuracy.

    ● Results can be simultaneously displayed as droplet images, and abnormal images are automatically saved for verification.

DVT Dynamic IFT Measurement Based on Droplet Volume

    ● Supports sinking droplets, rising droplets, and rising bubbles.

    ● Measurement range: 0.1–100 mN/m, resolution: 0.001 mN/m.

    ● Flow rate range: 0.6–2000 μL/min, drop detection: >60 Hz, volumetric resolution: 1 nL.

    ● Single rate/rate range mode, automatically scanning IFT at different interface lifetimes.

    ● QSD quasi-static dynamic mode reduces the influence of hydrodynamics and viscosity, improving accuracy.

    ● Supports simultaneous saving of images before and after droplet drop for verification and necessary result correction.

MDVT Maximum Suspended Droplet Volume Method

    ● Directly calculates IFT based on the maximum suspensible volume before droplet ...

    ● Flow rate range 0.6–2000 μL/min, shedding detection rate >60Hz.

    ● Single value/range mode, capable of automatically scanning to achieve the interface lifetime required for a specified IFT.

Reference Specifications：

Optics/Vision System

    ● High-brightness, highly uniform monochromatic LED backlight, brightness continuously adjustable by software.

    ● USB 3.0 monochrome CMOS industrial camera (6.3MP), maximum standard speed up to 183 fps (depending on mode).

    ● Field of view 1.8×2.9mm to 7.7×11.5mm (approx. 4.2× zoom).

Automatic Dispensing Unit (ADU)

    ● Software-controlled automatic dispensing system with 0.5 or 1.0 mL high-precision airtight syringe, volumetric resolution 0.001 μL.

    ● Flow rate range 0.3–7000 μL/min.

    ● Supports liquid addition, liquid subtraction, and up to 8 liquid addition modes (depending on the measurement method).

Instrument Frame and Standard Accessories

    ● Equipped with multi-axis adjustment (focusing, liquid addition unit y/z/t, sample lifting), including tilt adjustment of the liquid addition needle to maintain verticality.

    ● Instrument frame is made of German Item profiles.

    ● Includes various liquid addition needles, quartz cuvettes (with caps), and a dust cover.