Picosecond Laser Tissue Ablation With Controlled Pressure Waves

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Solution Overview

Problem

Current photothermal treatments for tissue damage and remodeling result in unwanted thermal damage to adjacent regions due to the necessary thermal rise for effective treatment, limiting the ability to precisely target and minimize collateral damage.

Innovation Solution

A system utilizing picosecond laser pulses with controlled pulse widths and fluences to create a combination of thermal and mechanical effects, allowing for precise tissue ablation and controlled pressure wave emission to minimize thermal damage to adjacent tissues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If photothermal treatment is used to achieve desired tissue treatment depth, then effective tissue damage and remodeling is achieved, but unwanted thermal damage occurs to adjacent regions

Engineering Contradiction:
Improvetreatment precisionVSAvoidthermal damage to adjacent regions
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of pulse duration from nanosecond to picosecond scale, and adjusts fluence to exceed electron ionization threshold. This parameter change shifts the dominant mechanism from photothermal to photomechanical, achieving precise tissue ablation without significant thermal diffusion to adjacent regions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal mechanism (photothermal effect) with a mechanical mechanism (photomechanical effect through electron ionization and shock wave generation). This substitution allows tissue damage through mechanical disruption rather than thermal heating, eliminating the harmful thermal diffusion to adjacent areas.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If longer pulse width is used, then greater thermal effect is achieved, but mechanical effect intensity decreases

Engineering Contradiction:
Improvethermal effectVSAvoidshock wave pressure intensity
Core Design Contradiction:
TemperatureVSStress or pressure

Solution Approach 1:

The patent makes the pulse width a dynamic, adjustable parameter that can be varied within the picosecond regime. By controlling pulse width dynamically, the system can optimize the balance between photomechanical shock wave generation and photothermal heating effects based on specific treatment requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent establishes a relationship between pulse width parameter and the resulting effect ratio. Shorter picosecond pulses favor mechanical shock wave generation, while longer pulses within the regime increase thermal effects, allowing parameter-based control of the treatment mechanism.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If multiple passes at different depths are used, then comprehensive tissue treatment is achieved, but treatment time increases

Engineering Contradiction:
Improvedepth controlVSAvoidtreatment time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent segments the treatment into multiple passes at different depths, with each pass targeting a specific depth range. The controller coordinates these segmented passes to comprehensively treat the tissue volume while optimizing overall treatment efficiency through systematic depth progression.

Inventive Principle:
Principle #1Segmentation

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 system achieves targeted tissue remodeling with reduced thermal damage to adjacent areas by using picosecond laser pulses to control pressure wave emission, promoting tissue regeneration and healing through controlled mechanical injury.

Implementation Method 1

a fluence sufficient to exceed the electron ionization threshold of the target to result in an ablation volume of at least a portion of the target

Methodology Applied
Scientific EffectElectron ionization: Photoionisation

Implementation Method 2

The cavitation bubble expands and collapses to generate shock waves and pressure waves that propagate through adjacent tissue

Methodology Applied
Scientific EffectCavitation: Cavitation

Implementation Method 3

The shock waves and pressure waves cause mechanical disruption and heating of adjacent tissue

Methodology Applied
Scientific EffectAcoustic radiation pressure: Acoustic Radiation Pressure

Implementation Method 4

The shock waves and pressure waves cause mechanical disruption and heating of adjacent tissue

Methodology Applied
Scientific EffectViscous heating: Viscous Heating

Data Source

PatentEP4094876B1Controlled photomechanical and photothermal tissue treatment in the picosecond regime
Publication Date: 2025.07.02 CYNOSURE INC
  • EP4094876B1 patent drawingFigure 1A
  • EP4094876B1 patent drawingFigure 1B
  • EP4094876B1 patent drawingFigure 2(a)~2(b)

AI summary

Systems and methods for treating tissue by concentrating a laser emission to at least one depth at a fluence sufficient to create an ablation volume in at least a portion of the target tissue and controlling pulse width within the picosecond regime to provide a desired mechanical pressure in the form of shock waves and/or pressure waves.