A Phase-Shifted Surface Plasmon Resonance Sensor for Simultaneous Photoacoustic Volumetric Imaging and Spectroscopic...

Area of Science:

• Biomedical Optics
• Acoustic Sensing
• Nanophotonics

Background:

• Biomedical photoacoustic imaging requires sensitive ultrasonic detectors for simultaneous volumetric and spectroscopic analysis.
• Current detectors struggle with high sensitivity across broad spectral bandwidths for pressure transients.

Purpose of the Study:

• To develop a novel surface plasmon resonance (SPR) sensor for broadband measurement of photoacoustically induced pressure transients.
• To enhance detection sensitivity for improved photoacoustic applications.

Main Methods:

• Developed a novel SPR sensor utilizing phase-shifted interrogation to detect ultrasonic perturbations via phase shift of surface plasmons.
• Encoded acoustically modulated phase change into time-varying interference intensity.
• Integrated the sensor into an optical-resolution photoacoustic microscope.

Main Results:

• Achieved a five-fold sensitivity enhancement (∼98 Pa noise-equivalent pressure) compared to traditional reflectivity-mode SPR sensors (∼470 Pa).
• Retained a broadband acoustic response of ∼174 MHz.
• Successfully performed label-free in vivo imaging of a zebrafish eye, enabling simultaneous volumetric visualization and spectrally resolved discrimination.

Conclusions:

• The novel phase-shifted SPR sensor offers significantly improved detection sensitivity and broadband acoustic response for photoacoustic applications.
• This technology holds potential for advancing biomedical ultrasonic and photoacoustic investigations.
• Enabled simultaneous label-free imaging and spectral discrimination in a zebrafish eye model.