Liquid Transport of Heated Glycerol-Water Mixtures with Colloidal Fluorescent Particles through Multiple Biomass Layers

In this study, we report for the first time the use of colloidal fluorescent submicrometer-sized particles as tracers for microliter liquid transport through multilayered biomass. We showed that the in-plane spread and the trans-planar penetration of the liquid can be visualized by mapping the fluorescent particle distribution in each biomass layer using image analysis. The temperature and inter-layer connectivity were found to be vital factors determining the fate of the liquid transport. Inter-layer connectivity is influenced by both the physical connections among the layers and the property of the fluid filling the inter-layer pores. Utilizing this characteristic, we could use our visualization method to detect trace amounts of nano- to sub-micrometer impurities in one of the layers.