Design of directional transmission channel models for breast photoacoustic signals based on defect state structure

In the photoacoustic detection of breast cancer, the weak intensity and severe energy attenuation of photoacoustic signals excited by the breast tissue become an important factor limiting the efficient acquisition of the ultrasound transducer. To overcome this problem, we proposed a linear defect channel and bifurcated acoustic transmission channel models at the front of the ultrasonic transducers based on the phononic crystal bandgap characteristics and defect state structure. The results of numerical analyses and simulations carried out using COMSOL demonstrated that the photoacoustic signal transmission channel proposed could confine the acoustic energy within the defects, while achieving the directional transmission and local enhancement of the acoustic field of high-frequency breast photoacoustic signals. This design effectively reduces the signal transmission loss and amplifies the mammographic signal intensity, which is conducive to efficient acquisition. In addition, the directional transmission effect is found to be strongly dependent on frequency, which makes the channel have great frequency selectivity. Through the flexible modulation of the transmission path of the artificial acoustic structure, breast photoacoustic signals of specific frequencies can be exported in separate paths to reduce the interference of noise signals. This study combines biomedical tumor detection with phononic crystals to present a novel method for efficient acquisition and deep detection of acoustic signals in tissue photoacoustic detection from the signal perspective, which is conducive to improving the sensitivity of breast cancer detection.