Tracker™ - Pendant Drop Tensiometer for Surface Tension, Interfacial Tension, and Interfacial Rheology
One drop. One method. The complete picture of your interface — from equilibrium through dynamics to rheology.
The TRACKER is built entirely around axisymmetric drop shape analysis (ADSA) — a first-principles method. A precisely formed pendant or rising drop is suspended from a capillary tip, and its profile is captured by a high-resolution imaging system. The shape of that drop is governed by the balance between gravitational and surface forces, and ADSA works by fitting the experimentally observed profile to a theoretical curve derived from the Young-Laplace equation. The surface or interfacial tension is the value that produces the best fit between the Laplacian curve and the measured drop shape. Because the theoretical curve comes directly from the fundamental physics — not from calibration against a reference liquid, not from an empirical model, and not from mechanical contact with the interface — the result is a first-principles determination of surface tension. This is what Erbil describes as an absolute measurement of surface and interfacial tension.
A first-principles measurement is inherently the most reliable measurement a scientist can make, because it does not depend on assumptions, reference standards, or empirical models that may or may not apply to the system under study. It depends only on the physics. And because ADSA is also a non-contact optical method — the interface is observed, never touched — there is no mechanical interaction with the surface, no probe or plate, and no physical artifact introduced into the measurement.
This is the only measurement methodology the TRACKER uses, and it is the only methodology TECLIS offers. That is a deliberate choice. Where other instrument manufacturers provide both force-based tensiometry (Wilhelmy plate, du Noüy ring) and optical methods, TECLIS builds exclusively around ADSA — because we believe it is the most versatile and most rigorous approach to interfacial characterization available.
Force-based methods have a well-established role in surface science, particularly for pure liquid systems at equilibrium. But they require physical contact with the interface, which inherently limits what can be measured and under what conditions. A single pendant drop, analyzed optically, can do what no force method can: measure surface and interfacial tension as a continuous function of time, capture adsorption and desorption kinetics in real time, apply controlled oscillatory perturbations to probe the viscoelastic response of the interface, and do all of this under ambient or extreme conditions of temperature and pressure — from the same platform, with the same drop, in the same experiment.
For you, this means every measurement the TRACKER produces traces back to fundamental physics — not to a calibration curve, not to a correction factor, and not to an empirical model. It is the most direct, most versatile, and most accurate path from your sample to the answer you need.
“The drop shape method is an absolute measurement of surface and interfacial tension.”
— Surface Chemistry of Solid and Liquid Interfaces, Professor H. Y. Erbil, Blackwell Publishing, 2006
We designed the Tracker™ to be the most comprehensive tensiometer available.
Yet we also wanted it to have a modular design because everyone has different needs and goals.
The Tracker allows you to measure one, a couple, or all relevant surface and interface properties under wide-ranging environmental conditions. All with one instrument.
As your needs and application field grow, you can always add additional modules.
With the Tracker™, you have the freedom of choice.
Measure all relevant surface and interfacial properties
The Tracker™ modular design gives you the freedom and flexibility to invest in only those analytical modules that are important to your work. Measure:
Interfacial tension (liquid/liquid)
Surface tension (liquid-gas)
Adsorption/desorption kinetics
Interfacial Dilatational Rheology
Viscoelastic modulus
Coefficient of rigidity
Critical micelle concentration CMC
LaPlace pressure inside a bubble
Tensiometry at elevated pressures and temperatures
Critical micelle concentration (CMC)
Surfactants contain hydrophilic and hydrophobic parts. Due to this amphiphilic nature, surfactants can form spontaneous structures referred to as association or self-assembled colloids.
The simplest forms of association colloids are micelles. They are dynamic self-forming structures with various shapes (spherical, lamellar, disk, and cylindrical shaped) and sizes.
The most common and valuable measurement to understand micelles is the concentration at which micelles form spontaneously; the critical micelles concentration (CMC).
The Tracker™ intelligent CMC module automatically determines the critical micelle concentration using up to four different surfactant solutions. The injected volume and concentration are determined by an algorithm that calculates the concentration steps and volume amount to optimize the accuracy of the CMC determination.
The Tracker™ intelligent CMC module gives you extraordinary sensitivity and flexibility to understand complex surfactant interactions and micelle formations.
Phase Exchange Module
You can study the effects of solution chemistry and composition changes on the surface or interfacial layer inside or outside the formed bubble/droplet.
This phase exchange method is potent as it allows you to measure the sequential adsorption of different components at a liquid/liquid interface, in addition to the classic simultaneous adsorption measurement from a mixed solution.
Thus, for example, the movement of pre-adsorbed proteins after the successive addition of another surfactant can be successfully studied by this technique.
Measuring surfactant interface adsorption and desorption kinetics
Interfacial Rheology
Interfaces are dynamic entities. When working with solutions containing different or a mixture of surfactants, polymers, proteins, lipids, and particles, understanding the adsorption-desorption kinetics and surface/interface equilibrium arrangement is essential.
Calculating the viscoelastic modulus also allows you to deduce interfacial elasticity and viscosity effects on foam and emulsion stability.
With the Tracker™, you can control the drop/bubble volume and perform high-frequency sinusoidal variations with industry-leading precision giving you exceptionally accurate and repeatable viscoelasticity and rigidity data (for membrane-type interfaces and surfaces).
Surface Pressure
You can also control and measure the surface pressure using the Tracker.
Specific or custom-made interfaces can be made to mimic different interfacial systems and to study rheological properties at different interfacial pressures.
Thus, it is possible to determine the building blocks of an interface, study the adsorption of one or several molecules sequentially added, or determine the exclusion pressure of molecules.
It is a powerful and unique tool to study membranes like surfaces (e.g., lipid membranes)
Solid-liquid interfaces
In addition to all the surface and interfacial measurement capabilities, the Tracker™ also allows you to measure all relevant material surface properties of solids surfaces using the well-known sessile drop method (static and dynamic).
Measure static and dynamic (advancing and receding) contact angles in both ambient and under extreme temperatures and pressures.
Elevated Temperature and Pressure Module
Perform surface and interface/interfacial analysis at elevated temperatures and pressures up to 120 C (248 Fahrenheit)and 8 bars (116 psi) using the medium temperature and medium pressure module.
For ease of use, the syringe piston is accessible from outside the cell and can be automatically controlled. The cell pressure is controlled via the gas control box, which can be connected to any in-house pressure setup, gas cylinder, or compressor.
You can make multiple contact angle measurements without opening the high-pressure cell. This is due to the unique design of the pressure cell, which allows you to place several drops on or under a solid and then perform the contact angle measurement.
A separate thermocouple measures the temperature of the liquid inside the cell and is regulated via a dedicated temperature control box.
Tracker ™ - Measure Precisely. Formulate Confidently.
Analyze all vital and relevant surface and interfacial tension measurements with one instrument
