Localized surface plasmon resonance in nano-disc or nano particle arrays is a powerful tool for sensing biological assays. In this work, we exploit the fact that the resonance frequency of such structures is a function of geometrical profile or attachment of biological/chemical entities. The sensitivity of such a sensing structure is limited by its fixed geometry thus restricting the maximum sensing power only to few molecules. We have demonstrated a bio- sensing tool with wide range of tunability. It involves deposition of gold coated polystyrene (PS) nanospheres over a polydimethyl silixane (PDMS) substrate. Distribution of gold coated PS beads over PDMS is controlled by self-assembly procedures. By stretching the PDMS we have shown that sensing spectrum can be tuned, thus resulting in shift of sensing peaks, providing large sensing range within a single structure. Our devised structure will have many potential applications in bio-sensing. We have shown 80 nm peak shift as a result of stretching the PDMS substrate, and large shift is possible given further optimization.
© 2011 Optical Society of AmericaPDF Article