Nearly a half-century ago, scientists noticed that small particles flowing through a long tube can stay at a specific position along the cross-section of a tube. This is known as inertial focusing. Later, along with the development of microfluidic technology in recent decades, inertial focusing, a type of passive microfluidic manipulation technology, has emerged as one of the most powerful and precise cell manipulation techniques, with immense commercial potential in the bioengineering and pharmaceutical industries.