Figure depicting MANiAC synthesis. (A) Syringe with pre-aligned nanorods in liquid alginate is loaded into syringe pump and extracted at a rate of 100 μl/min. (B) MANiAC image. (Credit: Purdue University)

Tiny tumbling soft robots that can be controlled with rotating magnetic fields can climb slopes, tumble upstream against fluid flow, and deposit substances at precise locations in neural tissue. The “magnetically aligned nanorods in alginate capsules” (MANiACs) may be part of an advanced arsenal of drug-delivery technologies in the future.

A new study finds that when controlled using a magnetic field, the tiny tumbling soft robots can move against fluid flow, climb slopes and move about neural tissues, such as the spinal cord, and deposit substances at precise locations.

Magnetic fields are a particularly promising way to control things inside the body, as they are not influenced by tissues and tend to be very safe. This is the power behind the MANiACs, which are tiny tumbling robots containing magnetic nanorods encased in a soft spherical shell. These properties should allow them to safely tumble through the body in response to a magnetic field applied externally, with the goal of drawing them to a target site for drug delivery.

Under magnetic stimulation, the MANiACs successfully scaled slopes as steep as 45° and moved upstream against a fluid flow that was similar to what they would encounter in the nervous system. The researchers were able to maneuver dye-loaded MANiACs around on the surface of rodent neural tissues with a fine degree of control, and successfully deposited the dye in specific locations. They even re-dosed several locations to increase the amount of ‘drug’ dosed to that region.