Abstract
Biofilms are formed at interfaces between solid materials/environments or organisms’ tissues/ environments by bacterial activities. They are produced not only inside bodies, but also outside them. Inside bodies, the biofilm formation would lead to infection and chronic diseases, while it would lead to stickiness on various industrial materials followed by daily problems. However, the phenomena in both cases have essentially the same and common root. Therefore, it would be very informative for us to compare both cases to each other, when one would like to understand the mechanism, characteristics and to establish countermeasures. We authors have pursued the biofilm formation and growth in the case of problems outside body so far. Generally, the in-vitro biofilm research and evaluation should be composed of biofilm formations and the following quantitative measurements. And recently, we have gradually applied the concepts, methodology and principles to the research for biofilms formed inside the body, modifying them little by little. This paper will explain the modification process with many real successful and unsuccessful examples and propose the unsolved problems together with the history. Then we would like to give the reference guideline to design experimental processes for biofilm problems inside the body.