Not possible. Nano size is very very small size that is the size
comparable to wavelengths, atomic and molecular compound. If you
have a microchip that is in nano-sized, it'd probably gonna get
injested (eaten) by our friendly whitebloodcell. 
In order country, human microchipping is used for
addmission to clubs and pub. If you want go clubbing, you
needa scan the microchip at the entrance 