New attachment for electro-cautery knife could reduce surgical side effects

MechSE students Ian Denefe, Yatiraj Mundra, Daniel Stiles, Adi Wasserman, and Daniel Whitt presented their ME 470 senior design project in December: an improved electro-cautery knife. Electro-cautery is a surgical process in which the blade of a surgeon’s knife contains a current, heating the blade and cauterizing as it cuts the skin or other tissue. Cauterization causes the patient’s blood to coagulate so that there is little bleeding during surgery. 

The most common electro-cautery knives today have an adjustable power level setting. Most surgeons will set the power level at one setting (usually high) and leave it there throughout the surgery. This can be dangerous for the patient because different types of tissue have different levels of resistance. The high power level can damage less resistant tissue, with possible side effects including increased scarring and recovery time as well as infection. 

“Our solution was to come up with a new electro-cautery knife that senses what type of tissue it’s cutting through and automatically adjusts the power level to the minimum effective level,” said the students.

The three types of tissue that need to be identified are fat, muscle, and skin. After researching five different methods for identifying tissue, the team concluded that the most effective method uses the tissue’s electrical properties. “The main reason for this is that the data is really distinct for different types of tissues,” they said. 

The team then built and tested prototypes of three different designs. Two variations incorporated an electrode placed on the tissue ahead of the blade, whereas the third had sensors on the blade itself. The readings from the sensors placed on the skin were found to be indistinct, so the students focused on their third design. The final prototype has electrodes running along the blade that are connected to an Arduino, a microcontroller that uses preprogrammed data to translate the sensor readings into the correct type of tissue. 

“This uses a lot of energy and generates a lot of heat and vapors. In order to ensure that the data isn’t significantly affected by all these things going on, we decided to have the blade switch between a sensing period and a cutting period,” said the students. During the sensing period, the blade senses the type of tissue that it’s touching to determine the appropriate power level. In a demonstration using chicken tissues, their prototype correctly identified each type of tissue it was cutting. 

The team worked with and received funding from Carle Foundation Hospital, with additional funding from Shell Corporation. Their faculty advisor was MechSE professor Iwona Jasiuk.

For future groups pursuing this project, the team suggests updating the current code. “Our code only includes the three tissue types that we were able to test. It could be expanded to include, say, liver or heart, creating even more safety value,” they said.