Peter Reader-Harris

Reproducible Surface-Enhanced Raman Quantification of Biomarkers in Multicomponent Mixtures

Direct and quantitative detection of unlabeled glycerophosphoinositol (GroPIns), an abundant cytosolic phosphoinositide derivative, would allow rapid evaluation of several malignant cell transformations. Here we report label-free analysis of GroPIns via surface-enhanced Raman spectroscopy (SERS) with a sensitivity of 200 nM, well below its apparent concentration in cells. Crucially, our SERS substrates, based on lithographically defined gold nanofeatures, can be used to predict accurately the GroPIns concentration even in multicomponent mixtures, avoiding the preliminary separation of individual compounds. Our results represent a critical step toward the creation of SERS-based biosensor for rapid, label-free, and reproducible detection of specific molecules, overcoming limits of current experimental methods.

Optical guided mode resonance filter on a flexible substrate

We demonstrate the operation of a flexible optical filter based on guided mode resonances that operates in the visible regime. The filter is fabricated on a free standing polymeric membrane of 1.3 μm thickness and we show how the geometrical design parameters of the filter determine its optical properties, and how various types of filter can be made with this scheme. To highlight the versatility and robustness of the approach, we mount a filter onto a collimated fibre output and demonstrate successful wavelength filtering.

Functional Metamaterials for Lab-on-Fiber

In this chapter we discuss a versatile method to functionalize the tip of optical fibers for lab-on-fiber applications. At variance with traditional direct writing methods, the photonic functionality is implemented on a flexible, ultrathin support hosting metallic nano-features that is applied on the tip of a fiber. Here we present and discuss several fabrication strategies that combine different substrates with alternative approaches to realize the metallic photonic layer. As a specific application example we focus on a method to filter spectrally the broadband light transmitted through a standard multimode fiber. The filter consists of a metallic nanowire grating on a polymeric substrate, which acts as a guided mode resonance filter with an additional Fano resonance. The advantages and limitations of the presented technique are discussed as well.

Advanced application of flexible metamaterials at visible frequencies

Flexible metamaterials (FMMs) at optical frequencies can conform to a wide range of target geometries whilst allowing their optical properties to be tuned post-fabrication. Here we discuss this potential by presenting our recent and preliminary results, obtained for FMMs at visible frequencies for sensing, filtering and imaging applications.

Biomolecular sensing for cancer diagnostics using highly reproducible SERS substrates

We developed a SERS biosensor based on gold fishnets fabricated by using e-beam lithography. This device is used for glycerophosphoinositol (GroPIns) molecule sensing. GroPIns is an abundant component of cell cytosol and high GroPIns levels have been reported in several tumour cells. We demonstrate that our SERS sensor is able to accurately and quantitatively determine the concentration of GroPIns. These results indicate that SERS may provide a novel platform technology to identify GroPIns profiles in disease pathogenesis.

Design and applications of flexible photonic membranes

In this paper we present the design and applications of flexible photonic membranes. We discuss their use as versatile photonic layers in the framework of lab-on-fibre applications, specifically focusing on the design of angular robust spectral filters. We also show alternative routes to their fabrication, highlighting the opportunities and limitations associated to each approach. Finally we present our preliminary results on the all-optical control over flexible membranes, as a potential method to fine-tune their opto-mechanical properties to the required application.