Researchers at TU Wien have developed a new method that is suitable for mechanical tensile testing of micro-and nanofibers. Special features (A New method developed for tensile testing) Samples can be reconnected and disconnected from the power sensor.
Testing hardness as the tensile strength of nanofibers (A New method developed for tensile testing) in the micro-range in an experiment is always a waste of time. In most cases, the samples should be glued to both ends. Not only does glue repair take time, but the sensor on which the glass fiber is glued cannot be reused.
Researchers at TU Wien, Mathis Nalbach, Philipp Thurner, and Georg Schitter, have developed a test system that overcomes these obstacles. The functional principle is as follows: A magnetic microsphere attached to nanofibers can be obtained with magnetic tweezers. This allows the balls to be inserted into the fork connected to the force sensor and thus connected to the sensor. Due to the fact that the magnetic ball can also be removed from the fork with magnetic tweezers, another nanofiber can be removed immediately. This significantly increases the permeability of the sample. The researchers recently introduced a patent-pending tester “NanoTens” in the Review of Scientific Instruments.
Adapted to the real circumstances
While the atomic force microscope can be used to examine the mechanical properties of glass fiber through a nano-penetration test, NanoTens can perform material tests for fibers at more relevant tensile loads. Philipp Thurner from the Biomechanics research department explains how it works: “You can think of the device as a microscopic forklift. The magnetic ball, which is glued to the fiber, is inserted into the fork. By moving the fork up or down, the fiber can now be tested under tensile load. This type of load is particularly relevant for biological fibers such as collagen fibrils. Physiologically, these are mainly loaded under tension, and therefore their mechanical properties are particularly relevant under precisely this load.”
The biomechanists Nalbach and Thurner mostly examine natural fibers such as collagen. Since their mechanical properties depend strongly on external conditions, it is important to also take these into account in tensile testing. “We are successful in this because tensile tests can be performed on a variety of media using NanoTens. For example, dry collagen fiber is brittle and stiff when wet or fully hydrated. Out,” he said. Mathis Nalbach, the first author of the study.
Increased quality and quantity
With their method, the researchers not only succeeded in mimicking the physiological conditions, but the results obtained with NanoTens also gained validity. This is because many measurements are needed to obtain meaningful results from biological materials such as collagen fibrils. “Conventional methods allow us to examine only one or two samples per week. This makes it almost impossible to perform statistically valid studies,” Nalbach said. Philipp Thurner added: “The new method allows immediate connection and disconnection of fibers. As a result – and because the sensor is reused – we can not only increase the number of tensile tests to 50 measurements per week but also the measurement accuracy.”
Traction tests can be performed – depending on the choice – in a wide range of power as well as power controlled by the control system. This is important because tensile testing methods generally assume that the material has linear tensile properties. However, this is not the case with biological tissues such as collagen fibrils: they are viscoelastic. Force-controlled tensile tests make it possible to investigate this viscoelasticity.
From invention to product
NanoTens is internationally patented by TU Wien. The validity of the method (TRL 6) was also confirmed, as read in the study by Nalbach et al. “The next step is to join forces with industrial partners. We hope to find the license number to help with your research and support. We are interested in working with industry on this topic, “said Mathis Nalbach. NanoTens are designed to be typically integrated into any indentation or atomic force microscope device. In addition to materials science, tensile testing is also used – and more – in the sciences. about wildlife, semiconductor technology, and electronics.
