Characteristics of megahertz resonant platform for evaluating sensitivity of photoacoustic contrast agent

Abstract

Abstract A platform designed exclusively for evaluating photoacoustic contrast agents is required to prevent deviations in the results caused by differences in the architecture of photoacoustic imaging systems. In this paper, we managed to develop an evaluation system using a cost-efficient laser diode running in megahertz frequency band. To increase the output signal, an acoustic resonance structure is introduced where the sample liquid is filled in a glass capillary embedded in a soft phantom. The optimal width and interval of the excitation pulse were investigated and found to be 230 ns and 4.92 μs, respectively. Experimental results on inks and Indocyanine green verified the feasibility and effectiveness of the platform. Next, as a non-resonant platform, the glass capillary was replaced with a soft tube to examine the signal enhancement effect of the resonance. The signal-to-noise ratio was on average improved 2.5-fold by the resonance occurring in the glass capillary. The success in improving the signal-to-noise ratio may ensure the lower requirement on the laser power, which could consequently suppress the cost of the evaluation platform.