Simple sensors that work in diverse natural environments: The micro-Clark sensor and biosensor family

In this review the developments made within area of needle-shaped Clark-type gas sensors are summarized. Emphasis will be on design and functioning sensors, but examples use in various environments also included. Microscale have been constructed for O2, N2O, NO, H2S CO2. The tip diameters often 10−70 μm, can considerably larger, O2 with tips down to < 2 μm. excellent long term stability conferred by enclosure electrochemistry behind a polymer membrane makes these suited not only very localized measurement including recording concentration profiles, environmental monitoring. high level virtual absence interferences make microsensors ideal as transducers biosensors. Biosensors CH4, NOx− (i.e., NO3− + NO2−), NO2−, Volatile Fatty Acids (VFAs), Urea, SO42- thus realized.