The 1966 film Fantastic Voyage inspired the concept of miniature machines traversing the human body to diagnose and treat disease. This once-futuristic vision is now being realized through the development of synthetic micro/nanorobots engineered for in vivo biomedical applications. In this talk, I will highlight recent advances in the design of microrobots powered by bioavailable fuels or externally applied fields such as ultrasound and magnetism. These systems enable a range of sophisticated capabilities, including biosensing, targeted drug delivery, bioimaging, and cellular isolation. I will discuss our recent work on ultrasound-propelled microrobots that achieve deep-tissue navigation and controllable drug release guided by real-time ultrasound imaging. In parallel, I will present biofuel-powered micro/nanomotors designed for effective tissue penetration and programmable therapeutic delivery, particularly in oncology settings. These platforms integrate responsive materials, wireless control, and clinical imaging interfaces, transforming synthetic motors into intelligent, adaptable therapeutic agents. Our results reveal the vast potential of medical microrobots in addressing unmet clinical needs across gastrointestinal disorders, inflammation, cancer, and precision medicine.