Foldable structures in small scale for medical application

• Main Author: Lim, Clarence Chi Yuin.
• Other Authors: Chen Yan
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Mechanical engineering::Surgical assistive technology
• Online Access: http://hdl.handle.net/10356/40562
• Institution: Nanyang Technological University

A number of self foldable deployable structures have been designed and investigated in this final year project for possible medical applications, such as clamping of blood vessels in minimally invasive surgical operations and planting of retractable filters in blood vessels. In this report, the author describes the process of researching through the various types of linkages and also the materials suitable for this device. The proposed design is the integration of deployable structures and Shape Memory Alloy (SMA). The foldability or deployment is achieved by the basic performance of a deployable structure while the automated actuation is the function of the SMA with the operating temperature as the control parameter. The blood vessel clamp device was achieved by integrating shape memory alloy hinges with linkages that allowed close contact foldability. The SMA hinges were trained in a configuration such that once a specific temperature is reached, the hinges will actuate the linkage to fold down from an expanded to collapsed state, thus shutting tight a blood vessel. The filter device in general adopts a similar design as the blood vessel clamp but with minor changes, such as the reversed SMA hinge configuration (from closed to open) and an addition of a netting to filter unwanted particles from the blood flow. To evaluate the effectiveness of the clamp device, a blood pump flow rig with an artificial brachial artery was used to simulate the pressures and forces involved when clamping a blood vessel. Another method of test for the hinge forces was a spring balance test. This allowed the author to know exactly what kind of load the clamps are capable of handling with the current hinge design. These results will also be used as a benchmark when future developments will improve the overall performance of the clamps. The report concludes with a comparison with similar devices currently in the market today, discussions on areas where future development should be concentrated on and also the marketability of these devices.