Perhaps you should try some spelling variations:
"Frontiers in neuroengineering" » "Frontiers in geoengineering", "Frontiers in bioengineering", "Frontiers in reengineering"
"Frontiers in microengineering" » "Frontiers in bioengineering", "Frontiers in geoengineering", "Frontiers in reengineering"
"frontiers in nanoengineering" » "frontiers in bioengineering", "frontiers in geoengineering"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("Frontiers in neuroengineering") OR ("Frontiers in microengineering"))) OR ("frontiers in nanoengineering")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"Frontiers in neuroengineering\") OR (\"Frontiers in microengineering\"))) or (\"frontiers in nanoengineering\"))".
• Removing quotes may allow a broader search: (((( Frontiers in neuroengineering ) OR ( Frontiers in microengineering ))) or ( frontiers in nanoengineering )).
• Adding a wildcard symbol may retrieve word variants: (((("Frontiers in neuroengineering") OR ("Frontiers in microengineering"))) or ("frontiers in nanoengineering"))*.