An integrated hybrid interference and absorption filter for fluorescence detection in lab-on-a-chip devices

Richard, Charles; Renaudin, Alan; Aimez, Vincent; Charette, Paul G.

doi:10.1039/b819080a

Cited by 67 publications

(49 citation statements)

References 13 publications

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“…In waveguidebased optical sensors, it has been demonstrated that a high refractive index superstrate layer on the waveguide surface results in lower limits of detection [6,7]. In integrated optical devices, multilayer thin films with high refractive index contrast are extensively used for the fabrication of optical interference filters and mirrors [8,9]. In addition to high refractive index, important requirements for high refractive index materials include high optical quality and transparency over the visible spectral range.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to high refractive index, important requirements for high refractive index materials include high optical quality and transparency over the visible spectral range. Film thickness control is also critical and the optimum thickness depends on the refractive index value and is usually between 30 and 150 nm [6][7][8][9]. Furthermore, a low temperature deposition process is frequently desirable to facilitate the integration of different optical components on substrates such as glass or plastic.…”

Section: Introductionmentioning

confidence: 99%

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Optical properties of high refractive index thin films processed at low-temperature

et al. 2012

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a b s t r a c tThis study reports on the first development of high refractive index thin film materials processed at temperatures not greater than 100°C. Three materials were synthesised by the sol-gel technique, each employing different transition metal precursors (niobium, tantalum and vanadium alkoxides). The optical properties of these materials were characterised by ellipsometry and the propagation losses at 638 nm were measured by the prism coupling method. It is shown that refractive indices as high as 1.870, 2.039 and 2.308 are obtained from niobium-, tantalum-and vanadium-based materials respectively, attributed to the influence of the transition metal atomic size on the condensation reactions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optical properties of high refractive index thin films processed at low-temperature

et al. 2012

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“…A significant limitation of the current design is lack of optical filters in the probe tip. The LODs reported here could be improved by integrating optical filters directly onto the tips of the fibers, thus reducing fluorescence background due to light scattering that occurs along the fiber length [55–57]. Nevertheless, our probes have the advantage of focusing into small channels (down to 15 µm deep × 50 µm wide), enabling their use for a variety of applications, such as electrophoresis.…”

Section: Resultsmentioning

confidence: 99%

Design and microfabrication of a miniature fiber optic probe with integrated lenses and mirrors for Raman and fluorescence measurements

et al. 2016

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Fiber optics coupled to components such as lenses and mirrors have seen extensive use as probes for Raman and fluorescence measurements. Probes can be placed directly on or into a sample to allow for simplified and remote application of these optical techniques. The size and complexity of such probes however limits their application. We have used microfabrication in polydimethylsiloxane (PDMS) to create compact probes that are 0.5 mm thick by 1 mm wide. The miniature probes incorporate pre-aligned mirrors, lenses, and two fiber optic guides to allow separate input and output optical paths suitable for Raman and fluorescence spectroscopy measurements. The fabricated probe has 70% unidirectional optical throughput and generates no spectral artifacts in the wavelength range of 200 to 800 nm. The probe is demonstrated for measurement of fluorescence within microfluidic devices and collection of Raman spectra from a pharmaceutical tablet. The fluorescence limit of detection was 6 nM when using the probe to measure resorufin inside a 150 µm inner diameter glass capillary, 100 nM for resorufin in a 60 µm deep × 100 µm wide PDMS channel, and 11 nM for fluorescein in a 25 µm deep × 80 µm wide glass channel. It is demonstrated that the same probe can be used on different sample types, e.g. microfluidic chips and tablets. Compared to existing Raman and fluorescence probes, the microfabricated probes enable measurement in smaller spaces and have lower fabrication cost.

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“…Despite several advantages of this filtering solution (single layer, low cost, simple integration into a-Si:H photodetectors) they are inefficient when excitation and emission wavelengths are in close proximity as in the case of small Stokes' shift fluorophores (Δλ < 50 nm). Other solutions based on interference filters exhibit higher filtering efficiencies but require a large number of layer pairs (up to 20) to be deposited and for each layer its thickness to be tuned accurately [15,16].…”

Section: Introductionmentioning

confidence: 99%

Modelling of diffraction grating based optical filters for fluorescence detection of biomolecules

Kovačič

Krč

Lipovšek

et al. 2014

Biomed. Opt. Express

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Abstract:The detection of biomolecules based on fluorescence measurements is a powerful diagnostic tool for the acquisition of genetic, proteomic and cellular information. One key performance limiting factor remains the integrated optical filter, which is designed to reject strong excitation light while transmitting weak emission (fluorescent) light to the photodetector. Conventional filters have several disadvantages. For instance absorbing filters, like those made from amorphous silicon carbide, exhibit low rejection ratios, especially in the case of small Stokes' shift fluorophores (e.g. green fluorescent protein GFP with λ exc = 480 nm and λ em = 510 nm), whereas interference filters comprising many layers require complex fabrication. This paper describes an alternative solution based on dielectric diffraction gratings. These filters are not only highly efficient but require a smaller number of manufacturing steps. Using FEM-based optical modelling as a design optimization tool, three filtering concepts are explored: (i) a diffraction grating fabricated on the surface of an absorbing filter, (ii) a diffraction grating embedded in a host material with a low refractive index, and (iii) a combination of an embedded grating and an absorbing filter. Both concepts involving an embedded grating show high rejection ratios (over 100,000) for the case of GFP, but also high sensitivity to manufacturing errors and variations in the incident angle of the excitation light. Despite this, simulations show that a 60 times improvement in the rejection ratio relative to a conventional flat absorbing filter can be obtained using an optimized embedded diffraction grating fabricated on top of an absorbing filter.

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An integrated hybrid interference and absorption filter for fluorescence detection in lab-on-a-chip devices

Cited by 67 publications

References 13 publications

Optical properties of high refractive index thin films processed at low-temperature

Optical properties of high refractive index thin films processed at low-temperature

Design and microfabrication of a miniature fiber optic probe with integrated lenses and mirrors for Raman and fluorescence measurements

Modelling of diffraction grating based optical filters for fluorescence detection of biomolecules

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