Driver electronics design and control for a total artificial heart linear motor.

For any implantable device size and efficiency are critical properties. Thus, a linear motor for a Total Artificial Heart was optimized with focus on driver electronics and control strategies. Hardware requirements were defined from power supply and motor setup. Four full bridges were chosen for the power electronics. Shunt resistors were set up for current measurement. Unipolar and bipolar switching for power electronics control were compared regarding current ripple and power losses. Here, unipolar switching showed smaller current ripple and required less power to create the necessary motor forces. Based on calculations for minimal power losses Lorentz force was distributed to the actor's four coils. The distribution was determined as ratio of effective magnetic flux through each coil, which was captured by a force test rig. Static and dynamic measurements under physiological conditions analyzed interaction of control and hardware and all efficiencies were over 89%. In conclusion, the designed electronics, optimized control strategy and applied current distribution create the required motor force and perform optimal under physiological conditions. The developed driver electronics and control offer optimized size and efficiency for any implantable or portable device with multiple independent motor coils. Graphical Abstract ᅟ.

Novel Optical Position Sensing for Miniaturized Applications and Validation in a Total Artificial Heart.

GOAL: This paper describes the development and testing of various position sensing systems (PSSs) for miniaturized long-term applications with a focus on their validation in a total artificial heart (TAH). After a short description of the TAH's functioning principle, the special requirements for the PSS resulting from the application in a TAH are investigated. METHODS: Three PSS's were designed according to these requirements. A specially designed test method was used to first validate each PSS for general use in a miniaturized application. This test method validated the speed, resolution, and accuracy requirements for the PSS. In a second step, the PSS's were integrated in a TAH to measure its stroke position for the drive control. In this application, further requirements apart from miniaturization were considered. Each PSS's functionality in the TAH was validated in a mock circulation loop, which simulates the human circulatory system. RESULTS: Two of the three designed PSS's showed satisfactory results for all tested requirements inside the pump, whereas the third PSS did not operate properly at full-pump capacity. The best performing PSS was chosen for further use in the TAH. It performed up to a beat rate of 220 b/m. CONCLUSION: The extensive validation resulted in an accurate, miniature PSS for a TAH. SIGNIFICANCE: Besides the use in a TAH, the presented PSS's can be employed in a wide use of miniaturized applications. The introduced testing method allows the validation for general miniaturized applications, e.g., linear motor drives.

System overview of the fully implantable destination therapy--ReinHeart-total artificial heart.

OBJECTIVES: Owing to the lack of suitable allografts, the demand for long-term mechanical circulatory support in patients with biventricular end-stage heart failure is rising. Currently available Total Artificial Heart (TAH) systems consist of pump units with only limited durability, percutaneous tubes and bulky external equipment that limit the quality of life. Therefore we are focusing on the development of a fully implantable, highly durable destination therapy total artificial heart. METHODS: The ReinHeart-TAH system consists of a passively filling pump unit driven by a low-wear linear drive between two artificial ventricles, an implantable control unit and a compliance chamber. The TAH is powered by a transcutaneous energy transmission system. The flow distribution inside the ventricles was analysed by fluid structure interaction simulation and particle image velocimetry measurements. Along with durability tests, the hydrodynamic performance and flow balance capability were evaluated in a mock circulation loop. Animal trials are ongoing. RESULTS: Based on fluid structure interaction simulation and particle image velocimetry, blood stagnation areas have been significantly reduced. In the mock circulation loop the ReinHeart-TAH generated a cardiac output of 5 l/min at an operating frequency of 120 bpm and an aortic pressure of 120/80 mmHg. The highly effective preload sensitivity of the passively filling ventricles allowed the sensorless integration of the Frank Starling mechanism. The ReinHeart-TAH effectively replaced the native heart's function in animals for up to 2 days. CONCLUSIONS: In vitro and in vivo testing showed a safe and effective function of the ReinHeart-TAH system. This has the potential to become an alternative to transplantation. However, before a first-in-man implant, chronic animal trials still have to be completed.