You picked the wrong preposition. That's all.
To my native ear, "inflicted to the medical devices" sounds nonsensical. Since you're comparing it to "inflicted by the mobile phones", it looks like you though the preposition "to" would indicate the target of the interference.
That's a fair guess. For other verbs, "to" can serve that purpose: "The damage caused to the medical devices" is one example. However, not every verb uses the same set of prepositions for the same purposes.
As this ngram shows, "inflicted on" occurs about twice as often as "inflicted by". That is the natural choice for expressing your intended meaning.
There is nothing wrong or odd about the notion of "interference inflicted on medical devices by mobile phones". There's also nothing strange about the notion of "interference caused to medical devices by mobile phones". The only oddity is that the verb "inflicted" doesn't play nicely with the preposition "to".
The Macmillan entry that you've cited lists this common pattern of usage directly below its definition:
inflict something on someone/something: the environmental damage we are inflicting on the Earth [emphasis mine]