Development of pH-ISFET sensors for the detection of bacterial activity

Ion sensitive field effect transistor (ISFET) microsensors including a SiO 2 /Si 3 N 4 pH-sensitive gate structure and a titanium/gold pseudo-electrode have been used to detect the activity of the Lactobacillus Acidophilus bacterium. The first results have shown that such applications require high bacterial concentrations and, therefore, small analysis volumes. Thus, the pH-ISFETs have been adapted by fabricating micro-tanks from plexiglas or poly-dimethylsiloxane (PDMS). Bacterial detection over several minutes has been made possible by monitoring pH variations. This will allow ChemFET microsensors to be developed for bacteriological applications and for clinical analysis in particular.