In-vitro measurement system for induced voltages in medical implants in magnetic resonance imaging

Certification of active medical implants for use in magnetic resonance imaging machines requires the testing of immunity with respect to radiofrequency voltages induced into the active electronics of the implants. The testing of immunity is typically performed on the bench using an injection circuitry. However, the injection test voltage must be determined under real exposure conditions as they would occur in real human inside MRI. We have developed an optical differential voltage probe to be used in electromagnetically hostile environments like magnetic resonance imaging that is able to deliver the full complex-valued voltage signal with a dynamic range of 120 dB and a frequency range from 100 kHz to 1 GHz and with a total measurement uncertainty of 1.14 dB.