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.