Transcutaneous dual tuned RF coil system voltage gain and efficiency evaluation for a passive implantable atrial defibrillator

Cardioversion of atrial fibrillation (AF) can be achieved by applying an electric shock to the heart (defibrillation). A cost-effective approach for internal cardioversion is by means of a subcutaneous passive implantable atrial defibrillator (PIAD). A circuit design using a dual tuned resonant circuit whose capacitance on the receiver side also serves as a voltage booster is proposed and evaluated. The circuit performance is characterised using a MATLAB based model and a PSpice simulation. The circuit exhibited inherent voltage gain stability with a reasonable voltage gain (V_Rx/V_Tx >; 0.3). Computed link efficiency modelling, estimated high link efficiency values of about 63.63% at the 208 kHz resonant frequency (26 mm air gap between coils). The above theoretical characterisation was supported by hardware prototyping which realised a system efficiency of 59.61% (best case).