What are robots called that are designed to operate at the nanoscale?

Robots designed to operate at the nanoscale are referred to as nanorobots. These are tiny machines that can perform specific tasks at the molecular or atomic level, utilizing advanced materials and engineering techniques to manipulate substances at a scale usually measured in nanometers (one billionth of a meter).

Nanorobots can be engineered to carry out a variety of functions, including targeted drug delivery, cellular repairs, and environmental monitoring. Because of their small size, they have unique properties that differentiate them from larger robots, making them suitable for applications in medicine, environmental science, and materials engineering.

The other options represent different concepts. Nanosensors are devices that detect and measure physical or chemical properties at the nanoscale but do not perform tasks like a robot. Nanocellulose is a renewable material derived from cellulose at the nanoscale, used primarily for its strength and lightweight properties, but is not a robot. Nanoparticles are tiny particles that have unique physical and chemical properties due to their small size, but they do not possess the capability to perform tasks autonomously like nanorobots.