[1] Univ Calif Santa Barbara, Phys, Santa Barbara, CA 93106 USA
[2] Univ Calif Santa Barbara, Calif NanoSyst Inst, Santa Barbara, CA 93106 USA
[3] Univ Calif Santa Barbara, Mol & Cellular Biol, Santa Barbara, CA 93106 USA
[4] Univ Calif Santa Barbara, Mech Engn, Santa Barbara, CA 93106 USA
[5] Univ Calif Santa Barbara, Ctr Bioengn, Santa Barbara, CA 93106 USA