Putting Electronic Cigarettes to the Test (image) Fraunhofer-Gesellschaft Caption E-cigarettes come in many different guises, yet they all have one thing in common: they only emit vapor when switched on. Credit © Fraunhofer WKI Usage Restrictions The picture may be used for editorial purposes only. It is protected by copyright. The use is free of charge if the reference is mentioned. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.