In a previous work we have developed a biosensor able to detect the Sarin gas at a concentration of 0.1 mg/m3 with only 30 s of incubation time [1]. In this work, we modified the biosensor in order to integrate it into a miniaturized prototype. The prototype is composed of the cell in which is inserted the biosensor, a little fan able to sampling air and an electronic circuit. The circuit is able to apply the potential, to register the current, to turn on‐off the fan and eventually give an alarm. The system was tested with paraoxon with satisfactory results.