[1] Univ Freiburg, Freiburg Ctr Interact Mat & Bioinspired Technol F, Freiburg, Germany
[2] Univ Freiburg, Dept Microsyst Engn IMTEK, Lab Sensors, Freiburg, Germany
[3] Imperial Coll London, Dept Chem Engn, London, England
[4] Imperial Coll London, Royal Sch Mines, Dept Bioengn, London, England