Robotically Controlled Laser May Improve Minimally Invasive Surgery

Robotic engineers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have developed a microrobot designed to steer a laser within the body to aid in minimally invasive surgery.

Current energy-delivering devices used for the cutting and drying of tissues and to stop internal bleeding need to be brought close to the target site, which limits precision and can cause unwanted burns in adjacent tissues, as well as the development of smoke. Lasers, though an appealing solution to aspects of that end, must meet a number of additional criteria to be considered for use. Due to the size of surgical lasers, levels of precision, repositioning, steering, and manipulation required for minimally invasive surgery, the direct use of lasers has been a barrier.

The microrobotic laser-steering end-effector (right) can be used as a fitted add-on accessory for existing endoscopic systems (left) for use in minimally invasive surgery. Courtesy of the Wyss Institute at Harvard University.

Work led by Robert Wood and Peter York of the Wyss Institute has yielded a microrobot measuring 6 × 16 mm that is capable of operating with high speed and precision and that can be integrated with existing endoscopic tools.

“To enable minimally invasive laser surgery inside the body, we devised a microrobotic approach that allows us to precisely direct a laser beam at small target sites in complex patterns within an anatomical area of interest,” said York, the first and corresponding author on the study and a postdoctoral fellow on Wood's microrobotics team. “With its large range of articulation, minimal footprint, and fast and precise action, this laser-steering end-effector has great potential to enhance surgical capabilities simply by being added to existing endoscopic devices in a plug-and-play fashion.”

For use in minimally invasive applications, the device had to be roughly the diameter of a drinking straw, and fairly nimble.

“We found that for steering and redirecting the laser beam, a configuration of three small mirrors that can rapidly rotate with respect to one another in a small ‘galvanometer’ design provided a sweet spot for our miniaturization effort,” said second author Rut Peña, a mechanical engineer with micro-manufacturing expertise in Wood’s group. “To get there, we leveraged methods from our microfabrication arsenal in which modular components are laminated step-wise onto a superstructure on the millimeter scale, a highly effective fabrication process when it comes to iterating on designs quickly in search of an optimum and delivering a robust strategy for mass-manufacturing a successful product.”

Demonstrations showed that the microrobot was effective in mapping out and following complicated trajectories, such as where multiple laser ablations could be performed with high speed over a large range and are repeatable with a high degree of accuracy.

In testing, the researchers attached the device to the end of a colonoscope for a simulated resection of polyps on a benchtop phantom tissue made of rubber. The team successfully guided the device through the tissue using teleoperation.

“In this multidisciplinary approach, we managed to harness our ability to rapidly prototype complex microrobotic mechanisms that we have developed over the past decade to provide clinicians with a nondisruptive solution that could allow them to advance the possibilities of minimally invasive surgeries in the human body with life-altering or potentially life-saving impact,” said Wood, senior author on the work and a professor of engineering and applied sciences.

Wood’s microrobotics researchers, along with technology translation experts at the Wyss Institute, patented their approach and are further de-risking their medical technology (MedTech) as an add-on for surgical endoscopes.

The research was published in Science Robotics (www.doi.org/10.1126/scirobotics.abf1523).