Tensile Testing of Medical Tubing and Catheters
Medical catheters are generally inserted into the body to inject or remove fluids, whereas medical tubing can broadly be associated with catheters or extended to external devices such as dialysis machines, feeding tubes, and intravenous (IV) therapy drips. Failure of these devices could result in severe patient injury. As a result, mechanical testing is a critical requirement to demonstrate device safety. In all testing applications, correct gripping is essential for obtaining accurate measurements.
Correct gripping of a medical catheter is a delicate balance between holding the material in place while avoiding premature specimen damage. Depending on the specimen, we recommend using pneumatic side-action grips with rubber-coated faces or pneumatic cord and yarn grips. For instances where tubing is more rigid, the pneumatic side-action grips are more appropriate. Conversely, for ductile catheters and tubing, we recommend using the cord and yarn grips. This will ensure secure fixture of your specimen while providing the user with control over air pressure.
For a similar reason, choosing an appropriate extensometer to accurately measure strain poses issues. When testing biomedical materials, we recommend using an automated extensometer, such as the AutoX 750. Automatic extensometers provide high-precision strain measurements, taking the specimen to failure without causing damage to the specimen by clamping force of an extensometer. The AutoX 750 has the ability to graduate the clamping force such that this damage is avoided.
These features are further useful for biomaterials given that strain can be accurately measured throughout the full range of travel. This allows users to reliably track the specimen to failure. Additionally, the arms used for measuring the strain are counterbalanced and operate on a nearly frictionless linear guidance system. This makes the arms virtually weightless and removes any influence of the arms on the material’s properties.
The AutoX can be used on manual testing systems, as well as on fully-automated testing systems that utilize robotic specimen handling. The automation associated with this feature reduces setup time and can allow for high throughput in cross-functional facilities such as research, development, and quality control labs.
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The AutoX 750 is a high-resolution, long-travel automatic contacting extensometer. It can be mounted onto any electromechanical 3300, 5500, or 5900 table top and floor model systems, as well as LX, DX, HDX, and KN static hydraulic testing systems. It is well suited for applications involving plastics, metals, biomedical, composites, elastomers, and more. The AutoX has a maximum travel of 750 mm and accuracy of ± 1 µm.
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Instron® testmaster™ 2 Automated Specimen Handling Systems enable a new dimension in testing productivity. Available as either complete turnkey solutions or installed on existing Instron testing instruments, the unique modular design accommodates tensile, flex, and hardness testing. System configurations consist of either a robot or a carousel for rotary specimen handling. Materials tested include metals, plastics, thin films, components, elastomers, and medical devices.
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