MIT researchers have developed a new system to jam wireless signals sent to medical implants by unauthorized users.implantable medical devices, like pacemakers.

The system would use a transmitter to jam unauthorized signals at an implant’s operating frequency, permitting only authorized users to communicate with it. Because the jamming transmitter, rather than the implant, would handle encryption and authentication, the system would work even with existing implants.

The jamming transmitter — which they call a shield — would be small enough to wear as a necklace or a watch.