Pre-assembled WGM Dip Sensor with Stem-Supported Resonator
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Solution Overview
Problem
Conventional whispering gallery mode (WGM) sensors require frequent optical repositioning, which is prone to disturbance by benchtop noises and can lead to scratches on the resonator, making them fragile and difficult to use for dip sensing applications without losing resonance.
Innovation Solution
A mechanically robust, pre-assembled WGM sensor with a stem-supported resonator and optically coupled fibers that can fit within small diameters, allowing for dipping into and removal from wells without losing resonance, featuring a stem-resonator-fiber assembly that maintains optical coupling and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional WGM sensors are used, then optical coupling can be achieved, but frequent optical repositioning is required which makes the sensor fragile and difficult to use for dip sensing
Solution Approach 1:
The optical fibers are pre-positioned and pre-coupled to the resonator at specific angles (e.g., 45 degrees) during assembly. This preliminary positioning ensures that the optical coupling is established before the sensor is deployed, eliminating the need for frequent repositioning during operation and maintaining resonance stability throughout the dip sensing process
Solution Approach 2:
The sensor is divided into distinct functional components: the resonator, the stem, and the optical fibers. Each component is optimized independently - the resonator for optical resonance, the stem for mechanical support and positioning, and the fibers for light transmission. This segmentation allows the optical coupling geometry to be fixed during assembly while the entire assembly remains flexible enough for dip sensing operations
2Measurement precision
If conventional WGM sensors are used, then sensing capability is achieved, but benchtop noises cause disturbances leading to scratches on the resonator
Solution Approach 1:
The optical coupling function is extracted from the resonator itself and implemented through separate optical fibers that are positioned at an angle to the resonator surface. This extraction removes the vulnerable point-contact coupling mechanism and replaces it with a more robust angled coupling geometry that is less sensitive to mechanical disturbances from benchtop noises
Solution Approach 2:
The angled configuration of the optical fibers relative to the resonator surface provides a mechanical buffer against disturbances. The angled contact geometry distributes mechanical stresses more evenly and prevents direct transmission of benchtop noise vibrations to the resonator, thereby protecting against scratches and maintaining measurement precision
3Volume of moving object
If WGM sensors are made compact for dip sensing, then they can fit in well plates, but maintaining mechanical integrity and optical coupling becomes difficult
Solution Approach 1:
The optical fibers are positioned at an angle (e.g., 45 degrees) relative to the resonator surface rather than in a planar configuration. This angular arrangement in three-dimensional space allows the optical coupling to be established without requiring the fibers to be in direct contact with the resonator surface, thereby reducing mechanical stress while maintaining optical coupling in a compact form factor suitable for well plate dip sensing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a compact, easy-to-use WGM sensor that maintains resonance during repeated dipping and lifting, reducing mechanical disturbances and extending the sensor's lifespan by eliminating the need for frequent optical repositioning.
Implementation Method 1
When light travels within a transparent medium of a circular cross section on a track near the surface of the medium by total internal reflection, the light superimposes onto itself after one cycle.
Implementation Method 2
feed and pickup optical fibers optically coupled with the WGM resonator
Data Source
AI summary
A robust sensor, suitable for dipping into fluid wells, includes (a) a stem; (b) a whispering gallery mode (“WGM”) resonator mechanically supported by the stem; and (c) feed and pickup optical fibers optically coupled with the WGM resonator and mechanically coupled with the stem, thereby defining a stem-resonator-fiber assembly, wherein a portion of the stem-resonator-fiber assembly including the WGM resonator can fit within an imaginary cylinder having a diameter of 7 mm (or 2 mm, or even 1 mm). Such a whispering gallery mode (“WGM”) dip sensor, including (1) a stem, (2) a WGM resonator, and (3) feed and pickup optical fibers, may be made by (a) fabricating the WGM resonator and the stem from an optical fiber; (b) fabricating tapers on the feed and pickup fibers; (c) positioning tapers of the feed and pickup fibers relative to the WGM resonator such that an optical coupling between the tapers and the WGM resonator is established; and (d) mechanically coupling the stem with the feed and pickup fibers.