Engineers from the University of California – San Diego have developed a noninvasive method to detect infection in prostheses, as well as in knee, hip, and other joint replacements.

The method consists of an improved version of electrical capacitance tomography, as well as a thin-film sensor that is sprayed on the prosthesis or replacement hardware to improve the imaging technique’s ability to detect infection or other issues, states a media release from UC San Diego.

“Current methods to detect infection require patients to undergo burdensome imaging procedures, such as an MRI, CAT scan, or x-rays,” says Ken Loh, a professor of structural engineering at the Jacobs School of Engineering at UC San Diego and the lead researcher on the project, in the release.

“By contrast, our method could be easily used in a doctor’s office or in the home and, potentially, provide quantitative diagnostic-relevant information about the extent and locations of the infection.”

PhD student Sumit Gapta assisted Loh in the project. Together, they improved the algorithm to make the imaging method process the measurement data more accurately, as well as developed the thin-film sensor.

The film is made of a conductive polymer matrix that is sensitive to pH, as well as carbon nanotubes embedded in the matrix that increase the material’s ability to conduct electricity more sensitively regardless of the pH level. Infections caused by different microorganisms often change the local pH in human cells and affect their ability to conduct electricity, the release explains.

To test their system, the researchers spray-coated a plastic rod—as a surrogate of an actual prosthesis—with the thin-film sensor and then exposed it to several solutions that changed its pH. After each exposure to a solution, the researchers used their prototype system to scan the rod to obtain electrical measurements for their ECT algorithm. The method successfully detected the location of the rod and a change in the rod’s electrical properties due to changes in pH, the release continues.

“The combination of these two techniques makes our method optimal and, potentially, highly sensitive to different complications related to these prostheses and implants,” Loh states.

Future uses for his method could include multilayered thin-film sensors coated onto prostheses where each layer can detect different signals, such as for monitoring stresses and strains of the actual prosthesis, loosening, infection and pH changes, according to Loh.

Currently, the method is at the proof-of-concept stage. The next steps would include refining the measurement setup and to conduct animal testing, which is about 3 years out, Loh continues.

[Source(s): University of Californi—San Diego, Science Daily]