Mechanical Tensile and Torsion Testing of COVID Test Swabs

Mechanical Testing of the Nasopharyngeal Test Swab

For manufacturers to verify that nasopharyngeal (nasal for short) swabs utilized for COVID-19 testing are both safe and effective, they must be mechanically tested using a materials testing system. The primary concern when evaluating the efficacy and safety of nasal swabs is ensuring the swab will not break when subjected to mechanical forces associated with the swab encountering an obstruction within the nasopharyngeal space. As nasal swabs are subjected to both axial and rotational forces when removing and rotating the swab, tensile and torsion test methods can be implemented to determine the swabs strength characteristics. By performing the above mechanical tests on swabs, manufacturers can verify the swabs they develop will meet safety requirements.

Tensile Testing

Tensile testing is performed on nasopharyngeal swabs to simulate the tensile force that would be exerted on a swab if it was caught on an obstruction while being removed from the patient’s nose/throat. Manufacturers can evaluate the maximum tensile force of swabs to confirm they will not break if caught within the nasal passage. 

The tensile test setup for nasopharyngeal swabs includes a universal testing machine with tensile grips such as manual vise or pneumatic vise grips. During the test, the two ends of the swab, clamped between the tensile grips, are pulled to determine properties such as the breaking strength and the elongation at break.

Torsion Testing

Torsion testing is performed on nasopharyngeal swabs to simulate the torque force that would be exerted on a swab if it was caught on an obstruction while being rotated within the patient’s nose/throat. Manufacturers can evaluate the maximum torque force of swabs to confirm they will not break if caught within the nasal passage.

An adequate torsion test setup for nasal swabs includes a materials testing machine with a grip integrated at the stationary end of the system to fasten the specimen, and a chuck jaw on the moving end to rotate the test specimen until failure. Mechanical properties such as maximum torque force and the number of rotations to failure are calculated.

Full blog post and recommended equipment can be found here: https://www.admetinc.ca/mechanical-tensile-and-torsion-testing-of-covid-...