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Publication Number
US-8195014-B2
Publication Date
2012-06-05
Expiration Date
Abstract
An apparatus and method for optically detecting the presence of an analyte in a solution is presented. An embodiment comprises a waveguide resonator that is optically coupled to a fluid in a fluidic conduit so that the resonant wavelength of the waveguide resonator is based on the refractive index of the fluid.
Core Innovation
The invention relates to an optical chemical detector for microfluidic analyte detection in a lab-on-a-chip configuration. It uses a substrate that includes a flow channel, and an optically resonant waveguide resonator mirror positioned in a region of the flow channel. The optically resonant element is optically resonant for a wavelength when the fluid has a corresponding refractive index, and the resonance shifts to a different wavelength when the refractive index changes.
A laser provides light having a spectral bandwidth that includes a first wavelength. The laser provides the light to the waveguide resonator mirror and receives reflected light that selectively includes the first wavelength when the fluid in the region has a first refractive index, and selectively includes a second wavelength when the fluid has a second refractive index. The system further provides a third light signal based on the first light signal and the second light signal, supporting analyte detection through optical resonance behavior.
The document further describes configurations that leverage resonance-dependent optical intensity response for analyte arrival signaling and analysis in a small detection region. It includes approaches that use resonance sensing to obtain intensity and phase effects and differential dual-resonator configurations for noise immunity and progression indications via time differentials. An external-cavity laser embodiment is also described, in which a fluid-index-driven wavelength shift is reflected to tune laser output intensity and derive analyte concentration.
Claims Coverage
The independent claims cover three main aspects of the invention: a sensor with a waveguide resonator mirror in a flow-channel region operating as a refractive-index-dependent wavelength-selective resonator with laser feedback, and two method variants for detecting analyte using wavelength-selective reflection from the resonator mirror and providing a third light signal based on first and second light signals. Across the independent claims, the refractive-index-dependent resonance and selective reflected wavelengths are central, with additional claim coverage focusing on analyte versus analyte-free discrimination and downstream signal generation.
Refractive-index-dependent waveguide resonator mirror in a flow-channel region
A substrate comprising a flow channel for conveying a fluid with a first region, and a waveguide resonator mirror comprising a first optically resonant element located within the first region, wherein the first optically resonant element is optically resonant for the first wavelength when the fluid in the first region has a first refractive index and optically resonant for a second wavelength when the fluid in the first region has a second refractive index.
Laser-to-resonator feedback using selectively returned wavelength(s)
A laser providing light having a spectral bandwidth that includes a first wavelength, wherein the laser provides the light to the waveguide resonator mirror, and wherein the laser receives the first wavelength from the waveguide resonator mirror when the fluid in the first region has the first refractive index.
External-cavity laser defined by laser and waveguide resonator mirror
The laser and the waveguide resonator mirror collectively define an external cavity laser.
Analyte detection by resonator-mirror reflection selectively including wavelengths based on refractive index
Providing a fluid in a flow channel having a first region, providing a first light signal from a laser characterized by a first spectral bandwidth, receiving the first light signal at a first waveguide resonator mirror with a first optically resonant element located within the first region and optically coupled with the fluid, reflecting a second light signal from the first waveguide resonator mirror to the first laser, wherein the second light signal selectively includes light having a first wavelength when the fluid in the first region has a first refractive index and selectively includes light having a second wavelength when the fluid in the first region has a second refractive index.
Third light signal based on first and second light signals
Providing a third light signal from the first waveguide resonator mirror, wherein the third light signal is based on the first light signal and the second light signal.
Analyte versus analyte-free wavelength-selective reflection
Reflecting a second light signal from the first waveguide resonator mirror to the first laser, wherein the second light signal selectively includes light having a first wavelength when the fluid in the first region comprises the first analyte and selectively includes light having a second wavelength when the fluid in the first region is first analyte-free.
Across the independent claims, the core claim coverage is the use of an optically resonant waveguide resonator mirror positioned within a flow channel region so that the refractive index of the fluid determines which wavelength is resonant and selectively returned to a laser. The methods then use reflected wavelength-selective signals to generate a third light signal based on first and second light signals for analyte detection, with analyte presence and absence discrimination expressed through the wavelength-selective reflected second light signal.
Stated Advantages
Resonance causes a highly non-linear optical intensity response enabling small detection regions.
Faster, more definitive analyte arrival signaling.
Noise immunity, including temperature and laser noise, via differential dual-resonator configurations.
Documented Applications
Microfluidic analyte detection in a lab-on-a-chip setting using an optical chemical detector.
Determining analyte concentration via wavelength shift and wavelength difference derived from resonator-mirror reflection.
Capillary electrophoresis-related operation using electrophoretic mobility considerations as part of analyte flow progression determination via time differentials.
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