plate

The Novacor design uses two blood-sac pusher plates to pump blood through the body.

The pusher plates are epoxy-bonded to a seamless trilaminar flexible blood sac, consisting of a butyl rubber layer sandwiched between two layers of the polyurethane Biomer.

Each beam-spring is connected to its own solenoid mechanism and extends down on opposite sides of the pump to the pusher plates. "In designing the solenoid, the challenge was coming up with something that would run for 100 million cycles a year, without requiring maintenance," Miller said.

The other ends of the beam-springs, connected to the pusher plates, initially meet with resistance from blood in the pump.

In the new design, the pusher plate actuating mechanism has been changed, the motor has been redesigned to include neodymium iron magnets instead of the previously used samarium cobalt, and smaller and faster electronics have reduced overall weight and increased system reliability.

The overall design still incorporates the linear actuated pusher plate concept, but the rotating cam mechanism has been replaced by a roller-screw drive.

Three Hall-effect sensors placed in the motor housing alert the controller to the rotary position of the motor from which the related pusher plate position can be calculated.