Photoacoustic Tensile Imaging

Photoacoustic (PA) imaging combines the high optical absorption contrast of optical imaging with the deep tissue penetration of ultrasound detection, offering great potential for functional imaging and disease diagnosis. However, current PA imaging methods mainly explore optical absorption properties of biological tissue. To the best of our knowledge, tensile measurement based on PA effect is still an untapped area to be explored. In this work, we propose photoacoustic tensile imaging (PATI), a new PA imaging modality enabling quantitative assessment of tensile stress in biological samples. PATI exploits the nonlinear PA response induced by dual-pulse laser excitation to establish a mapping between the applied tension and the increment of the nonlinear PA signal. By varying the temporal delay between the heating and detecting laser pulses, the relationship between tensile force and nonlinear PA characteristics is quantitatively analyzed. Phantom experiments demonstrate a strong correlation between the nonlinear PA signal intensity and the applied tensile force. These results confirm the feasibility of the proposed approach for tensile force monitoring, which holds potential in biomedical applications, such as vascular pressure monitoring.