Detector 1 (IMAGE) Johns Hopkins University Caption The prototype detector emits a tone that rises in pitch as the surgeon moves closer to a metal screw. Credit Jay VanRensselaer/JHU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.