Photoacoustic: A Versatile Nongenetic Method for High-Precision Neuromodulation

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Physics

Background:

• High-precision neuromodulation is crucial for neuroscience research and treating neurological disorders.
• Current optical methods like optogenetics require genetic transfection, limiting clinical use.
• Direct photothermal stimulation risks thermal damage due to significant temperature increases.

Purpose of the Study:

• Introduce photoacoustic (optoacoustic) neural stimulation as a novel, non-genetic optical approach.
• Highlight its high efficacy, spatial precision, safety, and versatility for neural modulation.
• Review the principles, transducer designs, and applications of photoacoustic neural stimulation.

Main Methods:

• Utilizing pulsed ultrasound generated by nanosecond laser pulses for neuron activation.
• Employing fiber-based photoacoustic emitters for sub-100-μm spatial precision.
• Developing various photoacoustic transducer platforms, including nanotransducers and soft lenses.

Main Results:

• Demonstrated effective neuron activation in wild-type neurons with low laser energy (μJ range).
• Achieved sub-100-μm spatial precision, surpassing conventional ultrasound methods.
• Showcased minimal temperature increase (<1 °C), preventing thermal tissue damage.
• Enabled noninvasive transcranial and dura-penetrating brain stimulation.

Conclusions:

• Photoacoustic neural stimulation is a highly effective, precise, and safe non-genetic neuromodulation technique.
• Its versatility and noninvasive nature offer significant potential for both research and clinical applications.
• Further development of transducer designs and understanding of challenges will expand its future use.