When a team of Vanderbilt University engineers sought a way to improve the reliability of positioning systems used in delicate nose and throat surgeries, coffee was the solution. Coffee grounds, that is.
The engineers designed a "granular jamming cap" filled with coffee grounds. The grounds form a thin layer inside a stretchy silicone cap adorned with reflective dots. Once on the patient's head, the cap is attached to a vacuum pump that sucks the air out, causing the grounds to conform closely to the contours of the patient's scalp.
Before the surgery begins, a scanner maps the precise location of each reflective dot relative to key features on the patient's head. During surgery, an overhead camera observes the position of the dots, allowing the navigation system to accurately track the position of the patient's head as the surgeon moves it. A monitor in the operating room displays the data in combination with a CT scan and the position of the surgeon's instruments for a 3-D view inside the patient's head.
This technology could replace one using markers that are taped to the head. That method is subject to slipping and jarring—movements that can cause large tracking errors during surgery. The coffee grounds approach has been found to reduce targeting errors by 83%.
"It's a very clever way to greatly improve the accuracy of the guidance system when we are operating in the middle of a person's skull: a zone where the accuracy of the current system is inadequate," said Dr. Paul Russell, associate professor of otolaryngology at Vanderbilt.
The cap's key ingredient was thanks to Robert Webster, an associate professor of mechanical engineering and otolaryngology. He remembered reading of experiments that used coffee grounds to help robots grip objects.
The team presented their research at the recent International Conference on Information Processing in Computer-Assisted Interventions.
