Power
When it comes to powering the nanobots, there are also a variety of power solutions being explored by researchers. Solutions for powering nanobots include external power sources and onboard/internal power sources.
Internal power solutions include generators and capacitors. Generators onboard the nanobot could use the electrolytes found within the blood to produce energy, or nanobots could even be powered using the surrounding blood as a chemical catalyst that produces energy when combined with a chemical the nanobot carries with it. Capacitors operate similarly to batteries, storing electrical energy that could be used to propel the nanobot. Other options like tiny nuclear power sources have even been considered.
As far as external power sources go, incredibly small, thin wires could tether the nanobots to an outside power source. Such wires could be made out of miniature fiber optic cables, sending pulses of light down the wires and having the actual electricity be generated within the nanobot.
Other external power solutions include magnetic fields or ultrasonic signals. Nanobots could employ something called a piezoelectric membrane, which is capable of collecting ultrasonic waves and transforming them into electrical power. Magnetic fields can be used to catalyze electrical currents within a closed conducting loop contained onboard the nanobot. As a bonus, the magnetic field could also be used to control the direction of the nanobot.