1. Institute of Flexible Electronics (IFE) Northwestern Polytechnical University (NPU) 127 West Youyi Road Xi'an 710072 P. R. China
2. Helmholtz Institute Ulm (HIU) Helmholtzstrasse 11 89081 Ulm Germany
3. Karlsruhe Institute of Technology (KIT) P.O. Box 3640 76021 Karlsruhe Germany