Evanescent Optical Fibers for Multidirectional Laser Lithotripsy
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Solution Overview
Problem
Existing laser lithotripsy techniques face challenges in effectively targeting asymmetric obstructions or obstructions flush with a bodily structure due to limitations in light emission directionality using end-firing optical fibers, which often require multiple optical fibers with distal tips, adding bulk to the catheter profile.
Innovation Solution
The use of optical fibers configured with geometric variations to create evanescent and non-evanescent portions, allowing laser light to be transmitted into a bodily fluid and generate shock waves for breaking down obstructions, such as calcified lesions, by geometrically tailoring the fiber to target specific obstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If end-firing optical fibers are used to transmit laser light, then the catheter can be simple in structure, but the ability to target asymmetric obstructions or obstructions flush with a bodily structure is limited due to fixed light emission directionality
Solution Approach 1:
The optical fiber is designed with different geometric properties at different locations along its length. Specifically, the fiber transitions from a first geometric configuration (with larger core and cladding dimensions) to a second geometric configuration (with smaller core and cladding dimensions). This local variation in geometry creates different evanescent field characteristics at different positions, enabling the fiber to emit light in multiple directions and target obstructions from various angles, thereby improving adaptability without requiring multiple separate fibers
Solution Approach 2:
The optical fiber is effectively segmented into different geometric portions along its length. The first portion has one geometric configuration while the second portion has a different configuration. This segmentation allows each portion to contribute differently to light emission patterns, with the transition zone creating evanescent fields that can propagate in multiple directions, thus achieving multi-directional targeting capability within a single continuous fiber structure
2Adaptability or versatility
If multiple optical fibers with distal tips are used to target different obstructions, then targeting flexibility improves, but the catheter profile becomes bulkier
Solution Approach 1:
Multiple functional capabilities that would traditionally require separate optical fibers are merged into a single optical fiber. By incorporating different geometric configurations along the length of one fiber, the invention achieves multi-directional light emission and multiple shock wave generating regions within a single catheter, thereby maintaining targeting flexibility while reducing the overall catheter profile and simplifying the device structure
3Productivity
If laser light is transmitted through standard optical fibers, then the fiber structure remains simple and uniform, but the efficiency of generating shock waves for breaking down obstructions is reduced
Solution Approach 1:
The geometric parameters of the optical fiber (core diameter, cladding diameter) are deliberately changed along its length to optimize shock wave generation efficiency. The transition from the first geometric configuration to the second geometric configuration creates specific evanescent field conditions that enhance light coupling into the surrounding fluid, thereby improving the efficiency of shock wave generation for breaking down obstructions
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
This configuration enables efficient fragmentation of obstructions with a single catheter by allowing multiple shock wave generating regions, improving targeting flexibility and reducing catheter bulk.
Implementation Method 1
portions of which are geometrically configured to allow evanescent modes of propagating laser light to be transmitted out of the fiber and into a shock wave medium
Implementation Method 2
Laser pulses are transmitted into and absorbed by a fluid within the catheter. This absorption process rapidly heats and vaporizes the fluid, thereby generating the rapidly expanding and collapsing vapor bubble, as well as the acoustic shock waves that propagate outward and modify the calcified plaque
Data Source
AI summary
A laser lithotripsy system may include a light energy source and a catheter. The catheter may comprise an optical fiber comprising a core and a cladding that encases the core. The optical fiber may be configured to be optically coupled to receive laser light from the light energy source. The optical fiber may include at least one evanescent portion and at least one non-evanescent portion. When light propagates through the core, an evanescent field may be transmitted out of the optical fiber in the evanescent portion and may not transmitted out of the optical fiber in the non-evanescent portion.