In order to accurately determine the volume concentrations of different molecular components of the vascularized thrombosis organ-on-a-chip models developed in the parent grant, the proposed supplement application will focus on building and testing a new imaging technology, which can acquire the experimental absorption spectra of various tissue components. Specifically, Colton McGarraugh at the Yao lab at Duke University will develop the ‘photoacoustic fingerprinting’ method, which will be used to identify different concentrations of varying molecules by comparing a variety of different photoacoustic measurements at different wavelengths and their ‘matched’ models in the simulated library. This new technology will have the potential to identify different proteins and larger molecules in the engineered tissues of the organ-on-a-chip system beyond hemoglobin, such as fat, proteins, fibrin, platelets, and glucose, and thus will enhance the technical capabilities of the photoacoustic imaging technology proposed in the parent grant.