Fast recovery, high sensitivity, high selectivity, and room temperature (RT) sensing characteristics of NO gas sensors are essential for environmental monitoring, artificial intelligence, and inflammatory diagnosis of asthma patients. However, the conventional semiconductor-type gas sensors have poor sensing characteristics that need to be solved, such as slow recovery speeds (>360 s), low sensitivity (3.8), and high operating temperatures (>300 °C). We propose here a memristor-based NO gas sensor as a gasistor (gas sensor + memory resistor) with SnO2, Ta2O5, and HfO2 films, which successfully demonstrated the feasibility of fast reaction/recovery (<1 s/90 ns) and high sensitivities such as 11.66 and 5.22 in Ta2O5 and HfO2 gasistors for NO gas, at RT. Furthermore, so as to reinforce the selectivity in multigas ambient, we suggest a parallel circuit using three kinds of gasistors having different sensitivities for NO, O2, and C2H6 gases, which results in an improvement of selectivity for the selected gas at RT.
Keywords: conductive filaments; gas sensor; memristor; recovery; sensitivity.