Laser-Optic Evaluation for Bond Quality of Polymeric Medical Tubing

Abstract

A noncontact, laser-optic based laser ultrasonic technique referred to as the thermo-acousto-photonic nondestructive evaluation (TAP-NDE) was utilized to investigate bond integrity and localized stiffening due to an attached wire stent on small-diameter polymeric medical tubing. Laser-generated interrogating ultrasonic waves in the tubing were detected by use of a fiber-tip interferometer (FTI) and a continuous wave HeNe laser. The time-frequency analysis of the generated dispersive waves was performed using the Gabor wavelet transform (GWT) that effectively decomposed the digitized waveguide mode enabling identification of defect characteristic frequency tendencies. Three different bond defects were evaluated: tensile pull, needle puncture, and crease. These induced flaws represent possible manufacturing defects such as de-bond, potential leak sources, and geometry irregularities. The frequency tendencies were found to uniquely identify each bond defect. Frequency tendencies were also found to uniquely identify localized stiffening due to an attached wire stent proving that this technique can unambiguously identify propagation modes from among nonpropagation modes or vibrations. These findings demonstrate the utility of TAP-NDE and the GWT for quality inspection of small-diameter polymeric medical tubing.