In addition to
极小/極小, you can also consider
迷你. There are too many words/idioms for
tiny, but these are the more common ones I can think of that are applicable in your context. Below is the explanation of each:
In the context you intend to use it in,
微 seems to be colloquial, e.g.
微触角. Note that you should not say
微的触角; it would not make much sense.
This is smaller than
小, and is probably the most commonly used word for
This translates to
extremely small or
minimal. It either implies that the object is one of the smallest among the likes or simply emphasizes/exaggerates the tiny aspect of the object.
This is tiny as well, but it can also imply the insignificance of the object. For example,
渺小的翅膀 can mean
the trivial wings. Be careful with the possible connotations of this word.
This is tiny and thin, which is probably a good word for antennas, i.e.
This literally translates to
tiny form/mode/model/version. As such, it is usually used when there is at least one larger version to compare with, e.g.
微型翅膀(the tiny wings) and
巨型翅膀 (the huge wings).
This is a load word from English, as you may have realized –
mini. It is almost always used in a colloquial context.