Superscript and special characters

In app.json you can specify custom capabilities with the unit defined in unit. This is fine for normal roman characters and digits, but how can I specify special characters such as μ or a sub- or superscript? Do I use Unicode UTF-16 or something? What would the syntax be?

The JSON standard supports UTF-8, UTF-16 and UTF-32. However, the default is UTF-8 and it is highly recommended to use that character encoding for your JSON documents.

  "units" : { "en" : "μA" }

Great, thanks.
Based on that I tested a bit more and for other characters such as superscripts I can use the UTF-16 code, e.g. for a cubic meter I can type "units": "m\u00b3" which renders well in the Homey UI.