Chiral Plasmonics on Flexible Substrates

Plasmonic on-chip devices are widely used in many areas, however, the substrates are mainly focused on glass or silica wafers, which are expensive, rigid, and fragile. Herein, fabrication of gold nanoparticle arrays using Hole-mask colloidal lithography (HMCL) has been carried out on flexible plastic substrates. This allows for altering nanoparticle shape, size and spacing throughout the fabrication process in a rapid, inexpensive manner. One interesting aspect of fabrication of flexible substrates, is that after fabrication, the flexible substrates containing plasmonic particles can be twisted into chiral shapes. We have carried out studies to better understand the relationship between macroscopic and microscopic chiroptical activity. Moreover, sensitive and selective biomolecular binding can be measured with such devices using circular dichroism or vibrational optical activity. In summary, this method allows for the possibility of tunable, portable, inexpensive, and flexible devices for a variety of applications including biosensing and opto-electronics.