Implementation of an optical method for the real-time determination of uniaxial strain and vessel mechanics

The determination of the mechanical properties of vascular growth substrates has seen increasing interest in the bioengineering field. Mechanical features such as rupture strength, compliance characteristics, and viscoelastic properties of vascular grafts are important for their design and are indicative of their success in vivo. Thus a simple inexpensive measurement technique for these parameters would be useful. In this report we describe the implementation of an optical method for the measurement of vessel distention under a transluminal pressure gradient. It is based on the concept of laser light occlusion and allows for real time noncontact diameter measurements of hollow vessels < or = 2 cm. We demonstrate precise and reproducible measurements of diameter changes of less than 10 microm and, further, with the simultaneous determination of both strain and luminal pressure, were able to determine the elastic modulus of commercially available polymeric vessels. Comparison of the manufacturer specifications and our own measurement of the elastic modulus of these vessels, validate the effectiveness of our system. The advantages of this technique are its relative low cost, ease of implementation, high resolution, and flexibility stemming from its modular setup.