Sensitive optical biosensors for unlabeled targets: a review.

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

The realization of miniaturized optofluidic platforms offers potential for achieving more functional and more compact devices. Such integrated systems bring fluid and light together and exploit their microscale interaction for a large variety of applications. The high sensitivity of compact microphotonic devices can generate effective microfluidic sensors, with integration capabilities. By turning the technology around, the exploitation of fluid properties holds the promise of highly flexible, tunable or reconfigurable microphotonic devices. We overview some of the exciting developments so far.

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Integrated optofluidics: A new river of light

Refractive index (RI) sensors based on optical resonance techniques are receiving a high degree of attention because of the need to develop simple, low-cost, high-throughput detection technologies for a number of applications. While the sensing mechanism of most of the reported RI sensors is similar, the construction is quite different from technique to technique. It is desirable to have a uniform mechanism for comparing the various RI sensing techniques, but to date there exists a degree of variation as to how the sensing performance is quantified. Here we set forth a rigorous definition for the detection limit of resonant RI sensors that accounts for all parameters that affect the detection performance. Our work will enable a standard approach for quantifying and comparing the performance of optical resonance-based RI sensors. Additionally, it will lead to design strategies for performance improvement of RI sensors.

On the performance quantification of resonant refractive index sensors

Optofluidics - the synergistic integration of photonics and microfluidics - has recently emerged as a new analytical field that provides a number of unique characteristics for enhanced sensing performance and simplification of microsystems. In this review, we describe various optofluidic architectures developed in the past five years, emphasize the mechanisms by which optofluidics enhances bio/chemical analysis capabilities, including sensing and the precise control of biological micro/nanoparticles, and envision new research directions to which optofluidics leads.

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Optofluidic microsystems for chemical and biological analysis

We report an experimental demonstration of an ultracompact biochemical sensor based on a two-dimensional photonic crystal microcavity. The microcavity, fabricated on a silicon-on-insulator substrate, is designed to have a resonant wavelength (λ) near 1.5 µm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n=1.0 to n=1.5. From observation of the shift in resonant wavelength, a change in ambient refractive index of Δn=0.002 is readily apparent. The correspondence between absolute refractive index and resonant wavelength agrees with numerical calculation to within 4% accuracy. The evaporation of water in a 5% glycerol mixture is also used to demonstrate the capability for in situ time-resolved sensing.

Ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity.

By measuring the resonant wavelength of a two-dimensional photonic crystal microcavity, we can detect the change in refractive index of 0.002. Evaporative process of water in 5% glycerol is used to demonstrate time-resolved sensing capability

Ultra compact biochemical sensor built with two dimensional photonic crystal microcavity

We report on time-resolved label-free monitoring of protein binding in a physiological buffer using a photonic crystal microcavity sensor of total area 50 μm2 with an effective detection area of 0.272 μm2. We use this ultracompact sensor to monitor the binding of anti-biotin to biotinylated-bovine serum albumin (b-BSA), and measure an affinity constant of 6.94 × 107 M−1. We show that this photonic crystal sensor can be used for anti-biotin detection at concentrations ranging from picomolar to micromolar. The lower limit of detection for anti-biotin is less than 20 pM, corresponding to less than 4.5 fg of bound material on the sensor surface and fewer than 80 molecules in the modal volume of the microcavity. The sensor also has the capability of measuring binding of small molecular species such as aromatic rings (98 Da). Furthermore, we show that the active surface of the sensor can be successfully regenerated and re-used in subsequent protein binding experiments. A comparison of experimental and theoretical data is given, and the current experimental limitations of the sensor with regard to noise are discussed.

Photonic crystal microcavity sensor for ultracompact monitoring of reaction kinetics and protein concentration

Photonic crystal sensors may be created from two and three dimensional photonic crystals by introducing defects The localization of the optical field in the defect region affords the ability to sense small volumes of analyte

Photonic crystal sensors

A photonic crystal sensor adapted for single nanoparticle detection is disclosed. Very small single particles and single molecules may be detected. The sensors may be adapted to allow differential measurements.

Laura Wills Mirkarimi

Papers

Ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity.

Ultra compact biochemical sensor built with two dimensional photonic crystal microcavity

Photonic crystal microcavity sensor for ultracompact monitoring of reaction kinetics and protein concentration

Photonic crystal sensors

Apparatus for single nanoparticle detection