Travel in Switzerland is very friendly with public transport. The absolute reference to find/check your best travel itinerary is www.sbb.ch (also available via app in Google and Apple Store).
It includes all transport options (bus, train, boat, tram). To reach Empa there are several options:
- 10-15 min walk from Dübendorf train station
- Busstop called: Dübendorf, Empa
- Tram stop called: Dübendorf, Giessen (tram line #12 which goes straight to the airport as well)
To get to Switzerland all airports are decent options (Zürich, Bern-Belp, Basel, Geneva), for short travel times, ZH-Airport is highly recommended.