New Patent Solves a Long-Standing Problem in Tensiometry -- and Paves the Way for Adaptive Capillary Optics

Patent Granted for the Double-Ring Tensiometer: Precise surface tension measurement without empirical correction factors, sample volume " 1 mL -- and physically based precision optics in the submillimeter range.

IMETER, a company specializing in precision measurement technology, has been granted German Patent No. 10 2025 002.744 for the double-ring tensiometer (DRT). The invention addresses a fundamental methodological flaw that has plagued the Du Nouey ring method since its introduction in the early 20th century: the reliance on empirical correction factors (Harkins & Jordan, 1930), which systematically fail for non-standard geometries and small sample volumes.

The measurement problem and its solution: The surface and interfacial tension of liquids is one of the most physically significant material properties--relevant in pharmacy, biotechnology, chemistry, and materials science. The ring method is the most widely used force-based technique worldwide for determining these properties. Its weakness: The evaluation relies on tabulated values that yield significant errors outside certain ring-to-density ratios. As a result, small-volume measurements below 5 mL have not been reliably possible until now. The DRT replaces these approximations with a direct numerical solution of the Young-Laplace equation. This requires a new instrumental basis, which is protected as a device in the patent. Measurements (0.8 mL of water, Decan, June 2025) confirm the theory--for water, with a correlation coefficient of r2 = 0.9997 between measured and calculated force-displacement pairs.

The unexpected consequence: capillary optics

The physical analysis of the DRT principle leads to a far-reaching insight: In the submillimeter range, the capillary interface naturally forms an almost perfectly spherical shape during ring extraction. For a sample configuration (vessel radius 100 mm, Galinstan as the measuring fluid), the calculation yields a Strehl ratio of 0.999, an RMS shape error of 1.2 nm, and a numerical aperture of 0.91 -- performance metrics that surpass those of ground precision optics. The focal length is continuously adjustable via the ring position; the corresponding force can be measured directly. The result is a _force-coupled adaptive optical system with intrinsic self-calibration_--without high voltage, without the risk of breakdown, and with broad fluid compatibility.

Arrays of DRT elements open up applications as biomimetic sensor-actuator systems (_light-emitting complex eye_): simultaneous adaptive optics, chemical sensing, acoustics, and light emission from a single MEMS-compatible component.

Licensing: IMETER is seeking licensing and technology partners to translate the DRT principle into commercial applications--in tensiometry as well as in adaptive optics, endoscopy, gas sensing, and microsystems technology. The patent has been granted; official publication is expected on February 18, 2027. An extension to a European and international patent (EPA/PCT) is in preparation. Interested partners can review the complete documentation prior to publication--upon request and subject to an NDA.

About IMETER - IMETER is a company based in Augsburg, Germany, that specializes in precision measurement methods for interfacial tension, contact angle, viscosity, and density. IMETER's measurement technology adheres to the principle of metrological transparency: fully traceable measurement uncertainties, deterministic measurement conditions, and evaluation based on first principles.

Contact and further information: Michael Breitwieser . IMETER . Augsburg M.Breitwieser@imeter.de; Ref.: https://www.imeter.de/?view=article&id=127

IMETER / MSB Breitwieser
Morellstr. 4
86159
Germany

https://imeter.de

Herr Michael
0821706450

m.breitwieser@imeter.de

IMETER / MSB Breitwieser is an unconventional company in Augsburg and is led by its founder, Dipl.-Ing. Michael Breitwieser. Mr. Breitwieser studied chemistry and managed an analytical laboratory; he programmed databases and equipment in the chemical industry and now, together with his highly unique and interdisciplinary team, focuses on the development of IMETER's definitive measurement technology for the effective and accurate measurement of surface tension, viscosity, density, and contact angle.

This release was published on openPR.