Laser-induced elastic wave classification: thermoelastic versus ablative regimes for all-optical elastography
Susobhan Das1, Alexander Schill1, Chih-Hao Liu1
1University of Houston, Department of Biomedical Engineering, Houston, Texas, United States.
Journal of Biomedical Optics
|March 20, 2020
Summary
Researchers developed a safe, all-optical method for assessing tissue biomechanics. This technique uses laser-induced elastic waves to determine tissue properties without physical contact, overcoming limitations of existing methods.
Area of Science:
- Biomedical Optics
- Tissue Biomechanics
- Non-invasive Imaging
Background:
- Shear wave optical coherence elastography (OCE) characterizes tissue mechanics via elastic waves.
- Current methods (contact, acoustic, pneumatic) have limitations in frequency and miniaturization for thin samples.
Purpose of the Study:
- To develop a non-contact, all-optical approach for tissue biomechanics assessment.
- To experimentally determine the boundary between thermoelastic and ablative regimes for safe laser-induced elastic wave generation.
Main Methods:
- Utilized a 532 nm pulsed laser for photothermal excitation to induce elastic waves.
- Employed graphite-doped phantoms and chicken liver for experiments.
- Detected elastic waves using line field low coherence holography and analyzed wave shape.
Main Results:
- Identified a transition from thermoelastic to ablative regimes based on nonlinear surface wave amplitude increase and wave shape transformation.
- Established a correlation between absorption coefficient and transition energy, applicable to biological samples.
Conclusions:
- Presented a methodology to define the boundary for safe elastic wave generation.
- Enables development of non-contact, all-optical microscale assessment of tissue biomechanics.
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