In order to provide the benefits of palpation to minimally invasive surgery, a team of engineers and doctors at Vanderbilt University headed by Pietro Valdastri, assistant professor of mechanical engineering and medicine, has designed a special-purpose wireless capsule equipped with a pressure sensor that fits through the small ports that surgeons use for what is also called “keyhole” surgery.
As the surgeon taps the capsule in different places, it sends information about its position and the force being applied to a computer that uses the data to produce a false-color map of the tissue stiffness. This map can reveal the location of tumors, arteries and other important structures that the cameras can’t see because they are covered by a layer of healthy tissue.
The palpation capsule designed at Valdastri’s Science and Technology of Robotics in Medicine (STORM) Lab is extremely simple. It is 0.6 inches wide and 2.4 inches long. It contains a pressure sensor, an accelerometer, a wireless transmitter, a magnetic field sensor and a small battery.
In desktop testing with tissue simulated with silicone gel, the researchers report that the capsule can measure the local stiffness of the tissue with a relative error less than 5 percent.