We demonstrated a novel carbon nanotube (CNT)-based microrocket that propels efficiently through the thrust generated by oxygen (O₂) bubbles. These self-propelled microrockets exhibit ultrafast propulsion in aqueous solutions as well as in Dulbecco’s modified Eagle’s medium (DMEM).

The microrocket generated a driving force of over 231 and 300 pN in DMEM containing 4% hydrogen peroxide (H₂O₂). The speed and distance traveled by the microrocket can be controlled by adjusting the concentration of H₂O₂.

The designed multifunctional microrocket has the ability to (i) rapidly target (~5 minutes) and efficiently capture (~85%) transferrin receptor–positive (TfR⁺) cancer cells from an artificial CTC-like suspension, (ii) magnetically isolate the captured cells from peripheral blood cells, and (iii) enable subsequent high-resolution imaging.

We envision that such self-powered micromotors could provide a novel and effective approach for the rapid and efficient extraction of circulating tumor cells (CTCs) from biological fluids, supporting early cancer diagnosis and detection of recurrence.