A Compact Maglev Pediatric Ventricular Assist Device with An Axial Gap Type Self-bearing Motor

Miniaturization of magnetically suspended motor has been strongly demanded to develop implantable continuous flow pediatric ventricular assist devices (VADs) with excellent blood compatibility. This study develops a compact axial gap type self-bearing motor for pediatric VADs. The magnetically levitated motor has a top stator, a bottom stator, and a centrifugal closed impeller which is sandwiched between both stators with identical shape. The impeller axial position is regulated with vector control. The inclination angle of the impeller is regulated using P+/-2-pole theory. The double stator self-bearing motor can enhance torque production with small device size. This paper investigates a miniaturized axial gap type self-bearing motor with height reduction considering anatomical compatibility for long-term in vivo evaluation of the magnetically levitated pediatric VAD. The developed self-bearing motor has an outer diameter of 30 mm and a height of 29 mm. The constructed magnetically levitated centrifugal blood pump was driven with non-contact operation in a closed loop circulation circuit. The maglev pediatric VAD prototype indicated that the flow rate can be regulated in the range of 0.5-2.5 L/min against a head pressure of 60-100 mmHg. The vibration amplitude of the levitated impeller was 0.02 mm in the axial direction, and the tilt angle was about 0.2 deg. The developed pediatric VAD demonstrated sufficient hydraulic and magnetic suspension performance for use in animal testing with device implantation.