Minimally Invasive Surgery (MIS) is a new class of surgical procedures in which the operation is performed with surgical instruments inserted through small incisions in the body. In contrast to open surgery, in which the organ or tissue is exposed through large incisions in the body, MIS procedures generally allow for faster recovery time, less pain and trauma, reduced risk of infection, and shorter hospital stays.
Cutting-edge endoscopes, catheters, and even surgeon-guided robots have been developed to perform these complex but beneficial procedures. While the field of MIS continues to expand into more complex procedures, surgical tools that enable these operations are becoming smaller and more flexible. One of the growing challenges when using these devices is providing knowledge to the surgeon as to where the tool is inside the body. Whether it’s a manually or robotically driven surgical instrument, knowing the precise location of the instrument tip, or even the shape and position of the entire instrument, is critical to a successful operation.
The roots of shape-sensing optical fiber technology started in 1996 at NASA’s Langley Research Center in Hampton, VA. Researchers were asked to provide 10,000 strain sensors for the X-33 Launch Vehicle with a weight budget of virtually zero. Using optical fiber with Fiber Bragg Grating (FBG) strain sensors was an obvious choice because of their light weight, but in order to get 10,000 FBG sensors on a single fiber with 1 cm or less spacing between each sensor, a new demodulation technique had to be used. NASA researchers developed Optical Frequency Domain Reflectometry (OFDR), a technique that permits tens of thousands of sensors with the same nominal reflected wavelength to be read with very high spatial resolution, giving the most complete picture of any of the viable fiber-optic technologies.