Thermally Enhanced Photoacoustic Remote Sensing for Non-Contact Imaging

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Solution Overview

Problem

Conventional photoacoustic imaging techniques require physical coupling to the sample, making them inappropriate for various clinical applications such as ophthalmic imaging, intraoperative imaging, and endoscopic procedures, due to their inability to non-invasively image subsurface structures.

Innovation Solution

The development of thermally enhanced photoacoustic remote sensing (TE-PARS) systems, which use excitation, signal enhancement, and interrogation beams focused below the sample surface to generate and detect photoacoustic signals without physical contact, enabling non-contact imaging with enhanced absorption contrast and resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional photoacoustic imaging techniques are used, then image formation is achieved through acoustic wave detection, but physical coupling to the sample is required which limits clinical applicability

Engineering Contradiction:

Improveclinical applicabilityVSAvoidphysical coupling requirement

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical coupling system (acoustic transducers requiring physical contact) with an optical detection system. The PARS technique uses optical beams to excite and detect photoacoustic signals through non-contact optical measurement of absorption changes, eliminating the need for mechanical coupling while maintaining imaging capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary (detection beam) that mediates between the excitation source and the sample. Instead of directly detecting acoustic waves requiring contact, the system uses optical absorption changes as an intermediary signal that can be measured non-contactually, bridging the gap between photoacoustic excitation and non-contact detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If photoacoustic remote sensing is used to eliminate physical contact, then clinical applicability is improved, but signal detection sensitivity may be compromised

Engineering Contradiction:

Improvenon-contact imaging capabilityVSAvoidsignal detection sensitivity

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary thermal enhancement by pre-heating the sample or excitation region before photoacoustic excitation. This preliminary thermal action increases the thermal expansion coefficient and Gruneisen parameter, thereby amplifying the photoacoustic signal generation efficiency and improving detection sensitivity in the non-contact PARS configuration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes key physical parameters including temperature (through thermal enhancement), wavelength (tuned to chromophore absorption peaks), and pulse duration to optimize photoacoustic signal generation. By adjusting these parameters, the system maintains high measurement precision and sensitivity while operating in non-contact mode.

Inventive Principle:

Principle #35Parameter changes

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

TE-PARS systems provide non-invasive imaging capabilities with improved absorption contrast and resolution, overcoming the limitations of conventional photoacoustic techniques by allowing imaging of subsurface structures without physical contact, suitable for clinical applications like ophthalmic imaging.

Implementation Method 1

nanosecond or picosecond laser pulses are directed into a sample causing the generation of thermo-elastic induced acoustic waves

Methodology Applied

Scientific EffectPhotoacoustic effect: Photoacoustic Effect

Implementation Method 2

causing the generation of thermo-elastic induced acoustic waves

Methodology Applied

Scientific EffectThermo-elastic effect:

Implementation Method 3

signal enhancement beams configured to modify the observation or generation of temperature and pressure signals

Methodology Applied

Scientific EffectOptical heating: Heating

Implementation Method 4

an optical system or collection of systems that focuses or directs the excitation beam or collection of beams at a first focal point or collection of focal points

Methodology Applied

Scientific EffectOptical focusing: Focusing

Implementation Method 5

an optical detector or collection of optical detectors to detect the returning portion or portions of the interrogation and or signal enhancement beams

Methodology Applied

Scientific EffectOptical detection:

Data Source

PatentUS20230355099A1PARS imaging methods

Publication Date: 2023.11.09 ILLUMISONICS INC

AI summary

A method for visualizing details in a sample including directing an excitation beam to an excitation location below a surface of the sample, to generate signals in the sample; directing an interrogation beam toward the excitation location of the sample; directing a signal enhancement beam to the sample, to raise a temperature of a portion of the sample by 5 Kelvin or less, compared to a temperature of the portion of the sample in absence of the signal enhancement beam; detecting a portion of the interrogation beam returning from the sample that is indicative of the generated signals.