Numerical and experimental investigation of absorbing polymer films suitable for boundary photoacoustic imaging

Abstract

One of the main challenges in conventional photoacoustic methods, is that thin biological samples typically have low optical absorption in the visible region. Therefore, it is often necessary to stain or label the sample with a color which provide sufficient absorption for the laser wavelength used in the scanning system. Unfortunately, the labeling often introduce unwanted properties to the biological sample of interest. Such properties are often difficult to separate from the actual properties of the object itself. Therefore, it is a rapidly growing interest in the field of biological imaging to develop a label-free imaging method. In this thesis, such a method is proposed by creating a photoacoustic film consisting of a solution of polydimethylsiloxane and black toner particles gathered from a laser printer cartridge. The film is then placed in the vicinity of the object to be imaged, and then reconstruct acoustic properties inside the object. The proposed method is denoted as a boundary photoacoustic method, since the image reconstruction depends fully on external wave sources. To benchmark and model the system, two non-biological photoacoustic films are fabricated with different amounts of toner particles. The first one has 0.5 grams of toner particles, while the other one has 1 gram of toner particles. The maximum of the mean intensity of the acoustic signal obtained from a small area of the PAF, increased by 9 % when the amount of toner particles was doubled.