**4. Conclusion**

In this chapter, the author described the study on biosensor development for both eutrophication and organic pollution as one of my studying fields. By focusing on the two keywords of eutrophication and organic pollution, the author was able to summarize for the first time a series of our developmental flows and their aims. In conclusion, our biosensors introduced here could not be put into practical use. Nonetheless, the author hope that the practical use of both Pi and BOD biosensors as a replacement of the conventional standard methods will be realized based on the knowledge obtained by our developmental study.
