A novel method of mitigating EMI on implantable medical devices: Experimental validation for UHF RFID reader/writers

A method of mitigating the electromagnetic inter-ference (EMI) due to wireless communication devices on im-plantable medical devices (IMDs) such as implantable cardiac-pacemakers and implantable cardioverter-defibrillators (ICDs) is newly proposed. The key feature of the proposed method is that it does not require any modification of the IMDs. This method is based on the use of a ldquomitigation signalrdquo which lies in the idle periods of the wireless communication device. By using this mitigation signal, the low frequency noise signal generated in the IMDs' internal circuits by nonlinear detection, can be reduced. This leads to a drastic improvement in the maximum interference distance. The proposed method is experimentally confirmed in this paper as applied to UHF RFID reader/writers. First, the proposed EMI mitigation method is detailed. An implementation of the method for UHF RFID reader/writers is then presented. The in vitro EMI experiment uses 3 types of actual implantable cardiac pacemakers. Finally, the mitigation results are shown. The results show the proposed method can greatly shorten the maximum interference distance by more than 90 % for all pacemakers. For example, the maximum interferen-ce distance of one pacemaker is reduced by 68 cm, from 71 cm to 3 cm.