Nanoscale optofluidic sensor arrays. Opt Express

School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
Optics Express (Impact Factor: 3.49). 03/2008; 16(3):1623-31. DOI: 10.1364/OE.16.001623
Source: PubMed


In this paper we introduce Nanoscale Optofluidic Sensor Arrays (NOSAs), which are an optofluidic architecture for performing highly parallel, label free detection of biomolecular interactions in aqueous environments. The architecture is based on the use of arrays of 1D photonic crystal resonators which are evanescently coupled to a single bus waveguide. Each resonator has a slightly different cavity spacing and is shown to independently shift its resonant peak in response to changes in refractive index in the region surrounding its cavity. We demonstrate through numerical simulation that by confining biomolecular binding to this region, limits of detection on the order of tens of attograms (ag) are possible. Experimental results demonstrate a refractive index (RI) detection limit of 7 x 10(-5) for this device. While other techniques such as SPR possess a equivalent RI detection limit, the advantage of this architecture lies in its potential for low mass limit of detection which is enabled by confining the size of the probed surface area.

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    • "Considering the multiple sensing performance and label-free biomolecular detection, photonic crystal sensor array is a better choice. Examples of such structures include that Yang et al. demonstrated a nanoscale photonic crystal sensor array on monolithic substrates using side-coupled resonant cavity arrays [30], S. Pal et al. designed a multiple nanocavity coupled device for error-corrected optical biosensing [31], and S. Mandal et al. proposed a nanoscale optofluidic sensor array based on a silicon waveguide with 1D (one dimensional) photonic crystal microcavity [32]. However, the drawbacks of these sensor arrays are that the scale is larger and fewer cavities could be allowed without crosstalk due to the limited bandwidth. "
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    ABSTRACT: In this work, we propose radius-graded photonic crystal sensor arrays applied on nano-scale optical platform for label-free biosensing. Two L3 cavities and two H1 cavities are multiplexed and interlaced on both sides of a photonic crystal W1 waveguide on the radius-graded photonic crystal slab. The optical sensing characteristics of the nanocavity structure are predicted by three-dimensional finite difference time domain (3D-FDTD) simulation. In response to the refractive index change of air holes surrounding the cavities, four interlaced and symmetrical cavities are shown to independently shift their resonant wavelength without crosstalk. The simulation results demonstrate the refractive index sensitivity of sensor array varies from 66.67 to 136.67 nm/RIU corresponding to the number of functionalized air holes ranged from 4 to 21. This design makes different cavities multiplexed on both sides of waveguide possible. Meanwhile, the radius-graded photonic crystal with more symmetrical and interlaced cavities is better for large integration in the sensor arrays.
    Full-text · Article · Sep 2014 · Sensors and Actuators A Physical
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    • "In the Ref. [17], sensor array consists of a silicon waveguide with a 1D PhC microcavity, which is realized on many separate silicon strips, rather than a monolithic silicon slab, and limits the enhancement of integration density. In addition, the extinction ratio of single notch of 1D photonic crystal microcavity in the Ref. [17] is only 4 $ 10 dB. While to the Ref. [18], when the number of sensors integrated on the monolithic platform is large, the spacing of the frequency peak of adjacent cavity is not wide enough. "
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    ABSTRACT: We theoretically investigate a flexible design of building nanoscale photonic crystal (PhC) integrated sensor array with low crosstalk. The proposed device consists of array of side-coupled PhC resonant cavities with high Q-factors over $2 times 10^{3}$. The extinction ratio of well-defined single resonance exceeds 30 dB. Each resonant cavity has different resonant wavelengths and independently shifts its resonance in response to the refractive index variations. With three-dimensional finite-difference time-domain (3D-FDTD) method, simulation results demonstrate that the proposed sensor array is desirable to perform monolithically integrated sensing and multiplexed detection. Particularly, the design method here makes it possible to effectively enhance sensor array integration density and simultaneously restrain crosstalk between each other adjacent sensors. The refractive index sensitivity of 100 nm/RIU and the crosstalk lower than $-$4 dB are observed, respectively. Both the specific result and the general idea are promising in future optical multiplexed sensing and nanophotonic integration.
    Full-text · Article · Feb 2014 · IEEE Photonics Journal
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    • "A limit of detection as low as 2 fg of analyte has been experimentally achieved on specific biotin–streptavidin model, revealing ultrahigh performance. In conclusion, a nanoscale optofluidic array sensor of 1D photonic crystal resonators evanescently coupled to a single bus waveguide, has been designed for performing highly parallel, label-free detection of biomolecular interactions in aqueous environments [15]. In particular, experimental results reveal a LOD as low as 7 × 10 −5 RIU for homogeneous sensing, while theoretical simulations indicate that limits of detection on the order of tens of attograms (ag) are possible by properly confining biomolecular binding in resonant microcavities. "
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    ABSTRACT: In this paper we propose, for the first time to our knowledge, the theoretical investigation of silicon nanocrystals-based sandwiched slot waveguides which are dispersion engineered for trace biochemical surface sensing in photonic structures using nonlinear effects. In particular, we have investigated the feasibility of a new concept of photonic sensor based on nonlinear effects, such as Four Wave Mixing and optical soliton excitation inside very short structures (only a few mm long). In order to investigate the sensor performance, a self-consistent mathematical model has been developed by taking into account the space-time pulse evolution coupled with the electron dynamics inside the nanocrystals. Several parametric simulations have been carried out in order to find the best device configurations for sensing operation in near infrared, around 1550 nm.
    Full-text · Article · Mar 2013 · Sensors and Actuators B Chemical
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