The measurement of contact angles on circular tubing surfaces using the captive bubble technique

Circular tubings are used extensively in biomedical implants and devices. It is desirable to determine contact angles on the inner or outer surfaces of such tubing in its final fabricated form. In this study, a technique for the measurement of contact angles on tubing surfaces in an aqueous environment is reported. This has particular applications to biomaterials research, where polymer tubings contact the biologic environment. In this technique, air or octane captive bubble dimensions can be measured, and an underwater contact angle calculated from these dimensions. The validity of the technique was experimentally confirmed using Solution Grade Biomer and NIH standard polyethylene surfaces.