Fig. B1.

Phantom study of measuring the PA absorption curves by using different samples and different background materials (i.e., gelatin and PE plastic). (a) Schematic of the experimental setup with gelatin as the background material. (b) PA signal acquired by the experimental setup with gelatin as the background. (c) Relative PA absorption curves of three different samples (i.e., pure water, 1 ml water +0.05 ml oil, 1 ml water +0.1 ml oil) for the gelatin group. (d) Schematic of the experimental setup with PE plastic as the background. (f) PA signal acquired by the experimental setup with PE plastic as the background material. (f) Relative PA absorption curves of three different samples (i.e., pure water, 1 ml water +0.05 ml oil, 1 ml water +0.1 ml oil) for the PE plastic group.