Wanting a machine to give you sensation is like wanting a function to give you a specific output. In one sense, it obviously does: how else do I get a specific output from a given? In a more important sense, however, the machine and function are pure mediation and we can no more get inputs and outputs out of machines than we can get 4.0169 out of nothing but f(x) = x3. You might as well ask your TV to make the power come out of the wall.
If you want to say that sensation is nothing but an act of the central nervous system I don’t know that I’d object, but it is only true in a way that allows for it to be just as true that the nervous system mediates sensation. Thinking that sensation can be just a machine is like thinking that entrance into Athens can be just the gate: in one way it certainly is – there is no other way in. But this is not true in a way that would allow us to remove the gate, ship it off to the desert somewhere, and have it work just as well as an entrance to Athens.