Development of an Educational Device Based on a Legacy Blood Centrifuge

Abstract

Lifetime of medical equipment in hospitals ranges between 1 to 16 years, depending on the usage and maintenance of the medical device. Reusing the obsolete medical devices, converting them to low-cost educational systems and cutting down the charge of new educational medical equipment is the aim of this study. The proposed system is retrofitted with new mechanical and electrical modifications which include system identification and Proportional-Integral (PI) controller based on MATLAB, incremental rotary encoder, zero crossing phase controlling dimming circuit and Arduino microcontroller. System identification was applied to represent the new modified system by z-transform. Acting stresses, displacement, and factor of safety tests were applied through motion study. The proposed new mechanical part integrated with the original system yielded a maximum stress of 11.09 MN/m2 which below the value of the yield strength of the plain carbon steel SAE 1030 which is 220 MN/m2, The maximum displacement was 0.2 mm and the minimum factor of safety was 3.7 leading to the fact that the newly designed shaft can support not only 11.09 MN/m2 but also 41.033 MN/m2 when rotating at 1000 RPM. The proposed system was designed, implemented and tested as the whole system was modelled by 97.7% best-fit using z-transform. Also, a clinical validation has achieved by means of four different blood parameters: glucose, cholesterol, creatinine, and turbidity.