High frequency optoacoustic microscopy.

Area of Science:

• Biomedical optics
• Acoustic imaging
• Microscopy

Background:

• Photoacoustic (optoacoustic) imaging is a hybrid modality leveraging differential optical absorption for high-contrast tissue visualization.
• Pulsed laser absorption generates acoustic signals, providing tissue-specific information at high spatial resolution.
• Optical contrast agents are crucial for enhancing absorption and scattering of light in biological tissues.

Purpose of the Study:

• To develop a scalable photoacoustic microscopy technology for high-resolution, volume imaging of biological samples.
• To achieve diffraction-limited spatial resolution in photoacoustic microscopy.
• To establish a versatile platform for generating and detecting laser-induced ultrasound signals.

Main Methods:

• Development of a versatile photoacoustic microscopy platform integrating a microchip laser and a measurement cell.
• Utilizing high-frequency ultrasound transducers (up to 400 MHz) for signal generation and detection.
• Evaluation using 2D optoacoustic imaging of embedded light-absorbing microparticles (Fe3O4 and black toner).

Main Results:

• The developed platform demonstrated unmatched spatial resolution in photoacoustic microscopy.
• High-frequency (400 MHz) signals from single 1 µm particles were recorded with a high signal-to-noise ratio (SNR) of 34 dB.
• Successful 2D optoacoustic imaging of microparticles within a polystyrene matrix was achieved.

Conclusions:

• The established photoacoustic microscopy platform enables scalable, high-resolution imaging of biological samples.
• The technology shows potential for advancing optical imaging down to the diffraction limit.
• The high SNR achieved demonstrates the platform's capability for sensitive detection of microscopic absorbers.