Photoacoustic temperature monitoring technology and biomedical applications

The temperature of an organism provides key insights into its physiological and pathological status. Temperature monitoring can effectively assess potential health issues and plays a critical role in thermal treatment. Photoacoustic imaging (PAI) has enabled multi-scale imaging, from cells to tissues and organs, where its high contrast, deep penetration, and high resolution make it an emerging tool in biomedical imaging field. Benefiting from the linear correlation between the Grüneisen parameter and temperature within the range of 10–55 ∘ C, the PAI has been developed as novel noninvasive label-free tool for temperature monitoring especially for thermotherapy mediated by laser, ultrasound, and microwave. Additionally, by utilizing temperature-responsive photoacoustic nanoprobes, the temperature information of the targeted organism can also be extracted with enhanced imaging contrast and specificity. This review elucidates the basic principles of temperature monitoring technology implemented by PAI, further highlighting the limitations of traditional photoacoustic thermometry, and summarizes recent technological advancements in analog simulation, calibration method, measurement accuracy, nanoprobe design, and wearable improvement. Furthermore, we discuss the biomedical applications of PA temperature monitoring technology in photothermal therapy and ultrasound therapy, finally, anticipating future developments in the field.