The complex biochemical mechanisms in cells have evolved over millions of years. Most research on intracellular mechanisms has focused on populations, leading to averaged data that obscure cell-cycle or cell-age dependent mechanisms. This highlights the necessity of single-cell analysis. Unlike snapshot analyses from flow cytometry, controlled cultivation of individual bacteria allows for examination of cellular responses to specific microenvironmental stimuli. A key challenge is how to cultivate and analyze living bacteria, which are only a few micrometers in size, in controlled microenvironments. To address this, microfluidic and micro-electronic techniques were developed on glass chips, enabling contactless isolation and reversible fixation of single bacteria using negative dielectrophoresis. Miniaturized octupole electrodes facilitate high-resolution, cell type-independent manipulations. A critical advancement was the creation of a novel “on-tube-seal” to connect macro to microfluidics, along with adhesion analysis for selecting cell-repellent coatings and optimizing cell isolation. Individual cells of Corynebacterium glutamicum were analyzed in these controlled environments, revealing faster growth rates and unprecedented bioanalytical resolution compared to population analysis. Overall, the technologies developed provide novel opportunities to study single cells, the fundamental units of life.
