An all-glass microfluidic network with integrated amorphous silicon photosensors for on-chip monitoring of enzymatic biochemical assay

A lab-on-chip system, integrating an all-glass microfluidics and on-chip optical detection, was developed and tested. The microfluidic network is etched in a glass substrate, which is then sealed with a glass cover by direct bonding. Thin film amorphous silicon photosensors have been fabricated on the sealed microfluidic substrate preventing the contamination of the micro-channels. The microfluidic network is then made accessible by opening inlets and outlets just prior to the use, ensuring the sterility of the device. The entire fabrication process relies on conventional photolithographic microfabrication techniques and is suitable for low-cost mass production of the device. The lab-on-chip system has been tested by implementing a chemiluminescent biochemical reaction. The inner channel walls of the microfluidic network are chemically functionalized with a layer of polymer brushes and horseradish peroxidase is immobilized into the coated channel. The results demonstrate the successful on-chip detection of hydrogen peroxide down to 18 mu M by using luminol and 4-iodophenol as enhancer agent

Diamond photonics platform enabled by femtosecond laser writing

We demonstrate the first buried optical waveguides in diamond using focused femtosecond laser pulses. The properties of nitrogen vacancy centers are preserved in the waveguides, making them promising for diamond-based magnetometers or quantum information systems.Comment: 24 pages, 6 figure

Integrated spatial multiplexing of heralded single photon sources

The non-deterministic nature of photon sources is a key limitation for single photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded single photon yield without enhancing the output noise. Here the intrinsic statistical limit of an individual source is surpassed by spatially multiplexing two monolithic silicon correlated photon pair sources, demonstrating a 62.4% increase in the heralded single photon output without an increase in unwanted multi-pair generation. We further demonstrate the scalability of this scheme by multiplexing photons generated in two waveguides pumped via an integrated coupler with a 63.1% increase in the heralded photon rate. This demonstration paves the way for a scalable architecture for multiplexing many photon sources in a compact integrated platform and achieving efficient two photon interference, required at the core of optical quantum computing and quantum communication protocols.Comment: 10 pages, 3 figures, comments welcom

Through-membrane electron-beam lithography for ultrathin membrane applications

We present a technique to fabricate ultrathin (down to 20 nm) uniform electron transparent windows at dedicated locations in a SiN membrane for in situ transmission electron microscopy experiments. An electron-beam (e-beam) resist is spray-coated on the backside of the membrane in a KOH- etched cavity in silicon which is patterned using through-membrane electron-beam lithography. This is a controlled way to make transparent windows in membranes, whilst the topside of the membrane remains undamaged and retains its flatness. Our approach was optimized for MEMS-based heating chips but can be applied to any chip design. We show two different applications of this technique for (1) fabrication of a nanogap electrode by means of electromigration in thin free-standing metal films and (2) making low-noise graphene nanopore devices

Understanding the interaction between energetic ions and freestanding graphene towards practical 2D perforation

We report experimentally and theoretically the behavior of freestanding graphene subject to bombardment of energetic ions, investigating the ability of large-scale patterning of freestanding graphene with nanometer sized features by focused ion beam technology. A precise control over the He+ and Ga+ irradiation offered by focused ion beam techniques enables to investigate the interaction of the energetic particles and graphene suspended with no support and allows determining sputter yields of the 2D lattice. We find strong dependency of the 2D sputter yield on the species and kinetic energy of the incident ion beams. Freestanding graphene shows material semi-transparency to He+ at high energies (10-30 keV) allowing the passage of >97% He+ particles without creating destructive lattice vacancy. Large Ga+ ions (5-30 keV), in contrast, collide far more often with the graphene lattice to impart significantly higher sputter yield of ~50%. Binary collision theory applied to monolayer and few-layer graphene can successfully elucidate this collision mechanism, in great agreement with experiments. Raman spectroscopy analysis corroborates the passage of a large fraction of He+ ions across graphene without much damaging the lattice whereas several colliding ions create single vacancy defects. Physical understanding of the interaction between energetic particles and suspended graphene can practically lead to reproducible and efficient pattern generation of unprecedentedly small features on 2D materials by design, manifested by our perforation of sub-5-nm pore arrays. This capability of nanometer scale precision patterning of freestanding 2D lattices shows practical applicability of the focused ion beam technology to 2D material processing for device fabrication and integration.Comment: 31 pages of main text (with 4 figures) plus 4 pages of supporting information (with 2 figures). Original article submitted to a journal for consideration for publicatio

All-optical atom surface traps implemented with one-dimensional planar diffractive microstructures

We characterize the loading, containment and optical properties of all-optical atom traps implemented by diffractive focusing with one-dimensional (1D) microstructures milled on gold films. These on-chip Fresnel lenses with focal lengths of the order of a few hundred microns produce optical-gradient-dipole traps. Cold atoms are loaded from a mirror magneto-optical trap (MMOT) centered a few hundred microns above the gold mirror surface. Details of loading optimization are reported and perspectives for future development of these structures are discussed.Comment: 7 pages, 15 figure

Fabrication of nanostructured free-standing Fresnel zone plate for neutral matter-waves microscopy

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