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Publication Number
US-8254733-B2
Publication Date
2012-08-28
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 provides a sensor and related methods for detecting an analyte in a fluid using an optically resonant waveguide resonator located within a flow channel. The flow channel includes a first region and a second region separated by a first distance, and is dimensioned and arranged to enable flow of the fluid from the second region to the first region. In the second region, a sample containing a first analyte is injected, and the refractive index of the fluid is based on the presence of the first analyte.
A first optically resonant element is located within the first region and is optically resonant for a first spectral component when the fluid has a first refractive index, and optically resonant for a second spectral component when the fluid has a second refractive index. The sensor includes optically coupled bus waveguides and an input port such that the first spectral component is returned to the input port under one refractive-index condition, and related embodiments use reflected spectral behavior between analyte-free and analyte-containing conditions.
In related embodiments, a processor induces injection of the sample at a first time, detects a change in resonance at a second time, and computes a time differential between the first time and the second time. Additional embodiments perform intensity-based or phase-based signal processing using an output light signal generated from coupled signals, and extend sensing to a second optically resonant element in another region of the flow channel to determine a property of the analyte.
Claims Coverage
The document includes four independent claims and one independent method claim, centered on an optically resonant waveguide or element whose resonance depends on fluid refractive index linked to analyte presence, combined with time-based detection and signal processing. Across these claims, five main inventive features are repeated in different forms: a two-region flow channel with a separation distance, analyte-linked refractive-index dependence, an optically resonant element with analyte-dependent spectral resonance, time-differential computation based on resonance or intensity changes, and waveguide-based return or phase/intensity processing.
Two-region flow channel with analyte injection and flow direction
A substrate comprising a flow channel for conveying a fluid, wherein the flow channel comprises a first region and a second region separated by a first distance, the flow channel being dimensioned and arranged to enable flow of the fluid from the second region to the first region, and wherein the second region is dimensioned and arranged to enable injection of a sample containing a first analyte into the fluid at the second region.
Optically resonant element with spectral components determined by fluid refractive index
A first optically resonant element located within the first region, wherein the first optically resonant element is optically resonant for a first spectral component when the fluid in the first region has a first refractive index, and wherein the first optically resonant element is optically resonant for a second spectral component when the fluid in the first region has a second refractive index, wherein the refractive index of the fluid is based on the presence of the first analyte.
Time differential between injection time and resonance-detection time
a processor, the processor operable to induce injection of the sample into the fluid at a first time, detect a change in the resonance of the first optically resonant element at a second time, and compute a time differential between the first time and the second time.
Waveguide resonator formed by bus waveguides returning spectral component to input port
a first bus waveguide and a second bus waveguide, wherein the first bus waveguide, second bus waveguide, and first optically resonant element collectively define a first waveguide resonator, and an input port, wherein the input port, first bus waveguide and second bus waveguide are optically coupled, wherein the first waveguide resonator is dimensioned and arranged to return the first spectral component to the input port when the fluid in the first region has the first index of refraction.
Phase-based output light intensity from coupled signals and time-differential computation
distributing an input light signal into a first light signal and a second light signal, receiving a third light signal from the first waveguide resonator, wherein the third light signal has a phase that is based on the presence of the analyte in the first region, coupling the second light signal and the third light signal at an output port, generating an output light signal whose intensity is based on the relative phases of the signals at the output port, and computing a time differential between the first time and a second time that is based on a change in the intensity of the output light signal.
Across the independent claims, the document covers sensors and methods that use a flow channel with separated regions to move analyte-containing fluid from a sample-injection region to a sensing region, rely on an optically resonant element whose resonance condition depends on the fluid refractive index tied to analyte presence, and compute a time differential between injection and a later resonance or intensity change time. Some embodiments further specify waveguide-resonator architectures that return or reflect spectral components to an input port, while other embodiments generate an output light signal based on relative phases of coupled signals and compute the time differential from intensity change.
Stated Advantages
Improved sensitivity via a non-linear intensity response (on-resonance versus off-resonance).
A small detection region matched to the analyte sample size.
Documented Applications
Optical chemical detector example for capillary electrophoresis using time-of-arrival processing.
Interferometer-based phase detection and multi-region differential sensing variants for analyte detection.
External cavity laser/mirror configuration where analyte concentration causes resonator-defined wavelength shifts and corresponding output intensity changes used to derive analyte identity/concentration.
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