Researchers at Columbia Engineering working on a project funded by NIH and the Agency for Science Technology and Research in Singapore have created an implantable microelectromechanical system (iMEMS) that can be safely implanted in a human body and can be controlled from outside.
The problem with implantable devices is the need to make sure that its various components are "safe" whatever happens (like the degradation of the casing in which they are contained). This is clearly not the case for batteries (they run out of steam after a while and need to be replaced, and even for the ones that can be externally recharged they remain dangerous if their casing fails). On the other hand you need some form of batteries to power MEMS.
This was the problem addressed by researchers at Columbia Engineering. They have shown how to create a complex iMEMS that can have moving parts controlled wirelessly through a magnetic field.
In particular they have created a drug dispenser and tested it for releasing specific quantities of anti-cancer drugs in a mice bone cancer model.
The iMEMS has been created through additive manufacturing (like 3D printing) using a hydrogel that is tissue compatible, ad hence can be implanted without any side effect. The process allows the creation of complex structures, in this case it was a number of receptacles for drug that can be released on command using a magnetic field that can spin a wheel inside the iMEMS bringing a specific receptacle to release the drug into the body. The movement is controlled via magnetic iron particles (see clip).
The challenge was to deposit layer by layer the hydrogel and they demonstrated a fabrication process that can do that and do it relatively fast (the drug dispenser was created in 30').
The researchers expect this approach to enable the fabrication of a variety of iMEMS, including functional components like valves, manifolds, pumps.