Enzyme-based hybrid micromotors and spermbots. (A) Enzyme-based hybrid micromotors consisting of a rolled-up microtube  (I) and template-based microtube  (II) with functionalized catalase. (B) The spermbots consist of a single sperm cell captured inside a rolled-up magnetic microtube  (I), wireless magnetic closed-loop control of spermbot  (II), and speed control by changing temperature (III). The insets show trajectories of a spermbot at 12°C and at 37°C over a time period of 10 s . Scale bars, 50 μm.