A micro-biosensor is a complex device and, at micro-nano scale, the stability of multiplefenomena interactions depends critically on a multitude offactors. To build a robust micro-biosensor, a special attention for reliability issues must be paid. In a previous work [7], solutions for building an amperometric microbiosensor based on the inhibition of the photosynthesis process at cyanobacteria, are introduced. In this paper, the improvement on reliability criteria ofthe innovative assembling system of the micro-biosensor is presented First, the technological conditions for performing the mounting processes where established following the directions resulting by the "design for reliability" approach. The devices where tested by accelerating the relaxing of the internal stresses. In a second stage, the technological conditions where optimised, based on the experimental reliability results.