The local free volume governs the macroscopic properties (e.g. diffusion properties, mechanical strength) of biopolymeris, biomembranes and other biomaterials. We use PALS to measure the size of the dynamic free volume holes at the sub-nanoscopic scale. We use PALS with other techniques to understand the relation between the composition, structure and properties of these systems. The approach used here can serve as a framework for rational design of materials for tissue engineering and contributes to a better understanding of the biophysics behind biomembranes and cancer.