Many hybrid devices integrate functional molecular or nanoparticle components with microstructures, as exemplified by the nanophotonic devices that couple emitters to optical resonators for potential use in single-molecule detection, precision magnetometry low threshold lasing and quantum information processing. These systems also illustrate a common difficulty for hybrid devices: although many proof-of-principle devices exist, practical applications face the challenge of how to incorporate large numbers of chemically diverse functional components into microfabricated resonators at precise locations. Here we show that the directed self-assembly of DNA origami onto lithographically patterned binding sites allows reliable and controllable coupling of molecular emitters to photonic crystal cavities (PCCs). The precision of this method is sufficient to enable us to visualize the local density of states within PCCs by simple wide-field microscopy and to resolve the antinodes of the cavity mode at a resolution of about one-tenth of a wavelength. By simply changing the number of binding sites, we program the delivery of up to seven DNA origami onto distinct antinodes within a single cavity and thereby digitally vary the intensity of the cavity emission. To demonstrate the scalability of our technique, we fabricate 65,536 independently programmed PCCs on a single chip. These features, in combination with the widely used modularity of DNA origami, suggest that our method is well suited for the rapid prototyping of a broad array of hybrid nanophotonic devices.

The accurate and reproducible control of intense electromagnetic fields localized on the nanoscale is essential for the engineering of optical sensors based on the surface-enhanced Raman scattering (SERS) effect. In this paper, using rigorous generalized Mie theory (GMT) calculations and a combined top-down/bottom-up nanofabrication approach, we design and experimentally demonstrate approximately 10(8) spatially averaged, reproducible SERS enhancement in deterministic aperiodic arrays of Au nanoparticles with different length scales. Deterministic aperiodic arrays of 200 nm diameter nanocylinders are first fabricated using electron-beam lithography on quartz substrates, and smaller size (30 nm diameter) Au nanoparticles are subsequently positioned by in situ Au reduction at regions of maximum field enhancement. These multiscale structures, which we call "plasmonic nanogalaxies", feature a cascade enhancement effect due to the strong electromagnetic interactions of small satellite nanoparticles with localized fields in aperiodic arrays of nanocylinders. The development of SERS substrates based on aperiodic arrays with different length scales provides a novel strategy to engineer plasmon-enhanced biosensors with chemical fingerprinting capability.

Artificial DNA nanostructures, such as DNA origami, have great potential as templates for the bottom-up fabrication of both biological and nonbiological nanodevices at a resolution unachievable by conventional top-down approaches. However, because origami are synthesized in solution, origami-templated devices cannot easily be studied or integrated into larger on-chip architectures. Electrostatic self-assembly of origami onto lithographically defined binding sites on Si/SiO2 substrates has been achieved, but conditions for optimal assembly have not been characterized, and the method requires high Mg2+ concentrations at which most devices aggregate. We present a quantitative study of parameters affecting origami placement, reproducibly achieving single-origami binding at 94±4% of sites, with 90% of these origami having an orientation within ±10° of their target orientation. Further, we introduce two techniques for converting electrostatic DNA-surface bonds to covalent bonds, allowing origami arrays to be used under a wide variety of Mg2+-free solution conditions.

DALI combines DNA origami with conventional top-down fabrication for creating designer high-resolution plasmonic nanostructures.

Deterministic Aperiodic (DA) arrays of gold (Au) nanoparticles are proposed as a novel approach for the engineering of reproducible surface enhanced Raman scattering (SERS) substrates. A set of DA and periodic arrays of cylindrical and triangular Au nanoparticles with diameters ranging between 50-110 nm and inter-particle separations between 25-100 nm were fabricated by e-beam lithography on quartz substrates. Using a molecular monolayer of pMA (p-mercaptoaniline) as a Raman reporter, we show that higher values of SERS enhancement factors can be achieved in DA structures compared to their periodic counterparts, and discuss the specific scaling rules of DA arrays with different morphologies. Electromagnetic field calculations based on the semi-analytical generalized Mie theory (GMT) fully support our findings and demonstrate the importance of morphology-dependent diffractive coupling (long-range interactions) for the engineering of the SERS response of DA arrays. Finally, we discuss optimization strategies based on the control of particles sizes and shapes, and we demonstrate that spatially-averaged SERS enhancement factors of the order of approximately 10(7) can be reproducibly obtained using DA arrays of Au nano-triangles. The ability to rigorously design lithographically fabricated DA arrays of metal nanoparticles enables the optimization and control of highly localized plasmonic fields for a variety of chip-scale devices, such as more reproducible SERS substrates, label-free bio-sensors and non-linear elements for nano-plasmonics.