Emerging fabrication techniques for 3D nano-structuring in plasmonics and single molecule studies

Abstract

The application of new methods and techniques to fields such as biology and medicine is becoming more and more demanding since the request of detailed information down to single molecules is a scientific necessity and a technical realistic possibility. In this effort a key role is played by emerging fabrication techniques. One of the hardest challenges is to incorporate the third dimension in the design and fabrication of novel devices. Significantly, this means that conventional nano-fabrication methods, intrinsically useful for planar structuring, have to be substituted or complemented with new approaches. In this paper we show how emerging techniques can be used for 3D structuring of noble metals down to nanoscale. In particular, the paper deals with electroless deposition of silver, ion and electron beam induced deposition, focused ion beam milling, and two-photon lithography. We exploited these techniques to fabricate different plasmonics nanolenses, nanoprobes and novel beads for optical tweezers. In the future these devices will be used for the manipulation and chemical investigation of single cells with sensitivity down to a few molecules in label free conditions and native environment. Although this paper is only devoted to nanofabrication, we foresee that the fields of biology and medicine will directly gain substantial advantages from this approach.

Nanoplasmonics Fundamentals and Surface-Enhanced Raman Scattering as a Physical Phenomenon

“…Note that recently there has been much active work done on other approaches to synthesis, SERS, and fluorescence-enhancement applications of the nanolens substrates [14,[56][57][58][59][60][61][62]. Currently, it is clear that such fully controllable and purposely designed nanolens optically enhancing substrates are highly promising for biomedical, environmental, defense, and other applications.…”

Advanced metal lift-offs and nanoimprint for plasmonic metal patterns

“…Typical nanofabrication approaches are based on well-established microfabrication tools, such as lift-off [13][14][15] and direct ion metal milling. 16,17 However, to make these techniques work at the nanoscale level, either advanced optimization or a derived breakthrough technology must be developed, since existing process recipes can only be properly optimized at the microscale level. Metal lift-off outside the pattern trench can be facilitated if metal deposition at the pattern sidewall is restricted and the base pattern height increases at 1.5 times that of the imprint side.…”

Stable Stretched Suspended DNA Molecules

“…The extremity of the molecule can, for example, be functionalized with biotin that can interact specifically with Streptavidin previously bound to a surface [4]. Here we briefly present a new application of the devices presented in [5][6][7][8][9][10][11] where no DNA modification is required. The method relies on the selfaggregation of DNA on teflonated super hydrophobic Silicon textured surface.…”