Johns Hopkins undergraduates have invented a small handheld metal detector to help doctors locate hidden orthopedic screws that need to be removed from patients' bodies.

Yes, very much like the metal detector used to find lost coins and (precious) metals in the sand.

The said device, which emits a tone that rises in pitch as the surgeon moves closer to the metal screw -serves as a surgical tool to guide the removal of the hardware (orthopedic screws).

According to Malcolm M. Lloyd, a physician and chief executive officer of Surgical Transformations:

"When orthopedic screws are difficult to find, removing them can require an expensive operation. Orthopedic surgeons told us it would be great to have a metal detector to locate these small, sometimes isolated screws.

These surgeons felt that expensive, time-consuming and more invasive surgical procedures could be avoided if such a metal detection tool was readily available.

We presented that challenge to the Johns Hopkins students last summer and gave them a set of requirements for this tool. They nailed every one of those goals. Their solution is very simple, elegant and more advanced than I expected. I thought their prototype was fantastic."

The prototype of the above described medical metal detector was devised and built over the past school year by eight Johns Hopkins biomedical engineering majors which was unveiled recently at the university's BME Design Day event.

A provisional patent covering the invention has already been applied for by Surgical Transformations (a Manhattan-based company that sponsored the project) and is moving it toward further refinement, clinical testing and possible sale to doctors in the coming years.

Find more details from the full report.

[In photo: After an orthopedic screw is located, the metal detector segment can be detached from the Hollow probe end (Photo A). The doctor can then insert a screwdriver through the hollow probe (Photo B) and unscrew the troublesome hardware (Photo C). Photo by Jay VanRensselaer]