Complex sentence: The solution was to imprint a pattern of tiny magnetic bars onto the surface of the garnet, when a small magnetic field was applied they would become magnetized, and the bubbles would "stick" to one end.
Split into simpler sentences: The solution was to imprint a pattern of tiny magnetic bars onto the surface of the garnet. When a small magnetic field was applied, they would become magnetized, and the bubbles would "stick" to one end.