Computer-aided design models of Prototype 1 with various impeller and magnetic coupling configurations: Prototype 1 measured 20 mm in diameter. Different configurations for impeller shown in (A), (B), (C), and (D) include variations in length, width, thickness, cross-sectional profile, angle, pitch, and number of blades. Different configurations for magnetic coupling include alternating vs continuous polarities, axial vs radial polarities, cylindrical vs tubular orientations, and bar vs arc segments.