Waveguide-based sensor

Inventors

Heideman, Rene Gerrit

Assignees

LioniX International BV

Abstract

A sensor for sensing a target chemical with high signal-to-noise ratio is disclosed. In some embodiments, the sensor comprises a sensing region that is optically coupled with an attenuation region. The sensing region receives optical stimulation that comprises light characterized by an excitation wavelength. In response to exposure to the target chemical, the sensing region fluoresces at a fluorescence wavelength. The attenuation region receives light from the fluorescing sensing region that includes light characterized by the fluorescence wavelength (i.e., signal) and light characterized by the excitation wavelength (i.e., noise). The attenuation region conveys the light to a detector that provides an electrical output signal based on the target chemical. While conveying the light, however, the attenuation region improves the signal-to-noise ratio by attenuating light characterized by the excitation wavelength more than light characterized by the fluorescence region.

Core Innovation

The invention describes a fluorescence chemical sensor that uses a first sensing region that comprises a first material and a first waveguide portion. The first material provides a fluorescence signal characterized by a fluorescence wavelength when exposed to a target chemical and light characterized by a first excitation wavelength. A corresponding attenuation region includes a second waveguide portion and a second material, where the second material has a first absorptivity at the excitation wavelength and a second absorptivity at the fluorescence wavelength, with the first absorptivity greater than the second absorptivity.

The attenuation region is dimensioned and arranged so that light propagating in the second waveguide portion evanescently couples with the second material, thereby enabling preferential attenuation of excitation-wavelength light relative to fluorescence-wavelength light. In a PLC-based implementation, the first surface waveguide on a substrate has a sensing region and an attenuation region, and the attenuation region receives light from the sensing region.

The attenuation region includes a second portion of the surface waveguide and a second material comprising a wavelength-selective absorbing dye configured with the stated excitation-versus-fluorescence absorptivity relationship. The disclosed sensor configurations further include structures in which the attenuation region is optically coupled to the wavelength-selective absorbing dye using shaped waveguide portions, and optionally include resonant elements and beam dump configurations.

The waveguide structures can be adapted to increase interaction, such as using spiral-shaped waveguides, and multi-sensor arrays can be provided to map chemical distribution across a substrate based on electrical output signals.

Claims Coverage

The document provides three independent claims. Across these, the central inventive concept is the use of a dimensioned attenuation region with wavelength-selective absorbing material and evanescent coupling that preferentially attenuates excitation-wavelength light more than fluorescence-wavelength light, in a waveguide or PLC sensor architecture.

Across the independent claims, the sensor architecture combines a fluorescence-generating sensing region with an attenuation region containing wavelength-selective absorbing material. The attenuation region is dimensioned and arranged to achieve evanescent coupling between waveguide-propagating light and the absorbing material, with absorptivity constrained to be greater at the excitation wavelength than at the fluorescence wavelength, and the method claim attenuates the excitation component by absorption from the evanescent field.

Stated Advantages

Documented Applications