High-Frequency 3D Photoacoustic Computed Tomography Using an Optical Microring Resonator

Area of Science:

• Biomedical Engineering
• Optical Imaging
• Acoustic Sensing

Background:

• 3D photoacoustic computed tomography (3D-PACT) is crucial for volumetric biological tissue imaging, demanding advanced acoustic sensors.
• Existing sensors often face limitations in size, detection bandwidth, and sensitivity, hindering 3D-PACT system development.

Purpose of the Study:

• To introduce a novel high-frequency 3D-PACT system utilizing a micro-ring resonator (MRR) as the acoustic sensor.
• To evaluate the performance of the MRR-based 3D-PACT system for biological tissue imaging.

Main Methods:

• Fabrication of an 80 μm diameter micro-ring resonator (MRR) acoustic sensor using nanoimprint lithography.
• Development of a transmission-mode 3D-PACT system incorporating the MRR sensor.
• Performance evaluation using in vitro phantoms, ex vivo mouse brain, and in vivo mouse ear and tadpole.

Main Results:

• The MRR sensor achieved a detection bandwidth of approximately 23 MHz.
• The system demonstrated an imaging depth of approximately 8 mm.
• Achieved lateral resolution of 114 μm and axial resolution of 57 μm.

Conclusions:

• The developed MRR-based 3D-PACT system provides high-frequency imaging capabilities for biological tissues.
• The system shows promise for structural, functional, and molecular imaging applications at depth.
• MRR sensors represent a significant advancement for high-performance 3D-PACT systems.