Resonant Sensors (United States)

Subwavelength resonant lattices fashioned as nano- and microstructured films represent a basis for a host of device concepts. Whereas the canonical physical properties are fully embodied in a one-dimensional periodic lattice, the final device constructs are often patterned in two-dimensionally-modulated films in which case we may refer to them as photonic crystal slabs, metamaterials, or metasurfaces. These surfaces can support lateral modes and localized field signatures with propagative and evanescent diffraction channels critically controlling the response. The governing principle of guided-mode, or lattice, resonance enables diverse spectral expressions such that a single-layer component can behave as a sensor, reflector, filter, or polarizer. This structural sparsity contrasts strongly with the venerable field of multi-layer thin-film optics that is basis for most optical components on the market today. The lattice resonance effect can be exploited in all major spectral regions with appropriate low-loss materials and fabrication resources. In this paper, we highlight resonant device technology and present our work on design, fabrication, and characterization of optical elements operating in the near-IR, mid-IR, and long-wave IR spectral regions. Examples of fabricated and tested devices include biological sensors, high-contrast-ratio polarizers, narrow-band notch filters, and wideband high reflectors.

Spatially resolved H2O and CO2 concentration and temperature values are presented for a scramjet cavity-burning ethylene fuel. A range of fueling rates are explored. Data was captured using an imaging Fourier transform spectrometer and interpreted through the application of spectroscopic modeling. First, averaging an ensemble of measurements yields high-resolution, wide-band spectra at each pixel of the image. Then, these spectra are modeled using the HITEMP database. This work demonstrates IFTS is a viable combustion diagnostics tool in high-speed combustion. Spatially resolved scalar values can be measured using a single “point- and-shoot” type instrument and a single look-angle. Continued research toward improving the physics-based modeling, specifically the effects of line-of-sight averaging, is still needed. This work, however, continues the use of IFTS on relevant combustion platforms.

We fabricated a novel single molecule nanosensor by integrating a solid-state nanopore and a double nanohole nanoaperture. The nanosensor employs Self-Induced Back-Action (SIBA) for optical trapping and enables SIBA-Actuated Nanopore Electrophoresis (SANE) for concurrent acquisition of bimodal optical and electrical signatures of molecular interactions. This work describes how to fabricate and use the SANE sensor to quantify antibody-ligand interactions. We describe how to analyze the bimodal optical-electrical data to improve upon the discrimination of antibody and ligand versus bound complex compared to electrical measurements alone. Example results for specific interaction detection are described for T-cell receptor-like antibodies (TCRmAbs) engineered to target peptide-presenting Major Histocompatibility Complex (pMHC) ligands, representing a model of target ligands presented on the surface of cancer cells. We also describe how to analyze the bimodal optical-electrical data to discriminate between specific and non-specific interactions between antibodies and ligands. Example results for non-specific interactions are shown for cancer-irrelevant TCRmAbs targeting the same pMHCs, as a control. These example results demonstrate the utility of the SANE sensor as a potential screening tool for ligand targets in cancer immunotherapy, though we believe that its potential uses are much broader.

This research addresses fuel biocontaminant sensing using resonant photonic gratings. The fundamental photonic resonance physics enables compact, economic sensors that provide a rapid, quantitative, and effective modality for detecting and monitoring biochemical bindings. Thus, we present resonant sensors and attendant surface chemistry targeting yeast cells as representative biofouling agents. We apply biorecognition elements (BREs) to functionalize the dielectric grating surface (TiO2) to produce a sensitive, quantitative wavelength shift-based assay for detecting Yarrowia yeast cells. Concanavalin A (Con A) is used as a BRE consisting of carbohydrate-binding proteins binding to ligands on the yeast cell surface. Corresponding resonance wavelength shifts are measured relative to concentration expressed in log10 [C] where C represents the concentration of cells in solution. The assay is shown to be highly specific for detecting Yarrowia cells in various concentrations. The experimental limit of detection (LOD) of the assay is 1.92 for yeast cells in culture media and 1.22 for cells in phosphate buffer saline (PBS). The comparisons of the various functionalization methods show that (3-aminopropyl)triethoxysilane (APTES) with glutardialdehyde (GA) and Con A protocol provides optimal detection of cells in PBS.

A high-accuracy biosensor system has been developed to provide rapid detection of biomarker proteins as indicators of ovarian cancer. This photonic detection system is based upon guided-mode resonance sensor technology. The buildup of the attaching biolayer can be monitored directly, without use of chemical tags, by following the corresponding resonance shift with a spectrometer or detector array. Additionally, these high-resolution sensors employ multiple resonance peaks at identical physical location on the sensor surface. Each of these resonance peaks responds uniquely to the detection event, thereby enriching the data set available for quantification. The peaks result from individual, polarization-dependent resonant leaky modes that are the foundation of this technology. Examples are presented for detection of ovarian cancer biomarkers (fibronectin and apoliprotein A-1) in serum and cell culture supernatant, with detection sensitivities to ~20 ng/ml. Minimal nonspecific binding was measured in cell media and serum backgrounds. We also present an example dual-polarization resonance response with corresponding backfitting results that illustrate the capability to distinguish between changes at the sensor surface due to biolayer adhesion and those due to sample background changes.

Optical leaky-mode resonance effects associated with periodic waveguides are reviewed and their application potential in biosensing is explained. Use of resonant sensors for label-free biochemical monitoring is described. Novel transmission-based sensor designs are discussed.

The enema has evolved through trial and error, not scientific investigation. Because little scientific base exists, the authors began their study of enemas by examining current nursing practice. They asked 24 experienced registered nurses to describe how they give enemas, and if they had seen any complications. Interviews were audiotaped, transcribed, and analyzed using qualitative analysis software. The authors found that the nurses emphasized patient cooperation, preparation, and comfort; had observed few complications, and had difficulty describing quantitative aspects of enemas (e.g., amount of solution given, speed of administration).