Why chemicals? Why not? For starters, the human body is not electronic. There’s electricity at work (mostly in the nerves), but humans run mostly on chemicals, so the use of a chemical chip has obvious advantages:

(from Phys.org) “We can, for example, send out signals to muscle synapses where the signalling system may not work for some reason. We know our chip works with common signalling substances, for example acetylcholine,” says Magnus Berggren, Professor of Organic Electronics and leader of the research group.

This could be used to bypass damaged nerves to control muscles directly, but this is only one possibility. Such chem-chips can be used for any type of signaling and control. Example: An artificial pancreas can have such a chip that monitors blood-sugar levels, then signals another chip to make insulin as needed.  The Next Step… With a basic circuit done, more complex circuitry can now be developed. That would include elements such as ion inverters and NAND gates… and memristors? Could happen. Then from there…

Source: Nature Communications and Phys.org via Engadget.