Harke SFT-A2 Surface Tensiometer

Overview

The Harke SFT-A2 Surface Tensiometer is a benchtop instrument engineered for high-precision measurement of surface tension and interfacial tension using the standardized Wilhelmy plate method. Based on classical force-balance principles, the system quantifies the vertical force exerted on a vertically immersed platinum plate as it contacts or withdraws from a liquid–air or liquid–liquid interface. This method conforms to internationally recognized standards including ASTM D971 (Standard Test Method for Surface and Interfacial Tension of Mineral Oils), ISO 6295 (Petroleum products — Determination of interfacial tension — Du Noüy ring method and Wilhelmy plate method), and DIN 53914 (Testing of plastics — Determination of surface tension). The SFT-A2 integrates a high-resolution load cell (0.01 mN/m resolution and accuracy), motorized precision stage with sub-micron repeatability, and embedded WinCE computing architecture—enabling robust, operator-independent measurements in QC laboratories, R&D centers, and academic surface science facilities.

Key Features

• High-fidelity force transduction: Dual-range load cell calibrated to deliver consistent 0.01 mN/m resolution and accuracy across the full 0–1000 mN/m dynamic range.
• Motorized Z-stage with programmable velocity profiles: 50 mm travel range, ±0.5 µm positional repeatability, and noise-free motion enabled by a custom low-backlash lead screw assembly.
• Real-time data acquisition at up to 23 readings per second, supporting transient interfacial relaxation studies and rapid screening protocols.
• Integrated temperature monitoring subsystem with ±0.01 °C accuracy; sensor output synchronized with tensiometric data streams for thermally referenced analysis.
• 7-inch color WinCE touchscreen interface with intuitive navigation, local data storage, and one-touch auto-zero functionality—eliminating manual drift correction.
• USB 2.0 host interface for direct export to external storage media and compatibility with standard HID peripherals including external mice and keyboards.

Sample Compatibility & Compliance

The SFT-A2 accommodates a broad spectrum of sample types—including aqueous surfactant solutions, polymer melts, crude oils, emulsions, biological fluids, and low-volatility organic phases—without requiring hardware modification. Its Wilhelmy plate geometry supports both static and dynamic interfacial tension measurements, including equilibrium and time-dependent adsorption kinetics. The instrument complies with GLP-aligned data integrity requirements: all measurements are timestamped, user-attributed, and stored with full audit trail metadata. Software-generated reports include raw force curves, derived tension values, temperature logs, and operator annotations—facilitating traceability under FDA 21 CFR Part 11 (when deployed with validated IT infrastructure) and ISO/IEC 17025 quality management systems.

Software & Data Management

The proprietary Harke Tensiometry Suite implements A3, A4, and A5 algorithm variants—each optimized for distinct interfacial scenarios such as volatile solvent systems (A3), high-viscosity interfaces (A4), or heterogeneous multiphase boundaries (A5). Core functionalities include real-time meniscus detection via electronic level sensing, automated baseline correction, dynamic curve fitting for advancing/receding contact angle estimation, and batch-mode processing of multi-sample datasets. All test results are stored in an indexed local database with search-by-date, sample ID, or operator name. Export formats include plain-text CSV and ORIGIN-compatible XY data files for downstream statistical modeling, regression analysis, or publication-grade figure generation.

Applications

• Surfactant formulation development and critical micelle concentration (CMC) determination
• Quality control of pharmaceutical excipients, coating agents, and inkjet inks
• Interfacial rheology screening for enhanced oil recovery (EOR) formulations
• Surface energy assessment of functionalized nanoparticles and nanocomposites
• Stability evaluation of food emulsions and cosmetic microemulsions
• Academic research in colloid and interface science, including Langmuir monolayer characterization

FAQ

What measurement principle does the SFT-A2 employ?
It utilizes the Wilhelmy plate method, measuring the wetting force on a calibrated platinum plate partially immersed in the test liquid.
Is temperature control integrated into the instrument?
The SFT-A2 includes a high-accuracy temperature sensor (±0.01 °C) with software-synchronized readout—but does not feature active thermal regulation; external thermostated baths are recommended for isothermal experiments.
Can the system measure interfacial tension between two immiscible liquids?
Yes—by immersing the plate at the liquid–liquid interface and selecting the appropriate interfacial mode in software.
Does the software support compliance with FDA 21 CFR Part 11?
The embedded software provides electronic signatures, audit trails, and secure user access levels; full Part 11 compliance requires deployment within a validated laboratory network environment.
What file formats are supported for data export?
Test data can be exported as CSV or ORIGIN-compatible ASCII files via USB flash drive.
Is the platinum plate included with the instrument?
Yes—a certified platinum plate (20 × 10 × 0.1 mm) is supplied as standard equipment, pre-calibrated and traceable to NIST-equivalent reference standards.