Multi-purpose ionization gas sensing devices using carbon nanofibers on plastic substrates

The authors present the study of carbon-nanofiber-based (CNF) ionization gas sensing devices on plastic substrates. The device is configured as diode structure with a Cu plate and a CNF film as anode and cathode respectively. The lowest breakdown voltage for He, Ar, air, N2, N2O, O2and C2H2is 215, 270, 400, 490, 540, 574 and 613 V with 5% of variations, respectively. For a fixed applied voltage of 600 V, the ionization current of the device exhibits two regions of linearity with respect to gas pressure below and above 5 Pa, suggesting that the device can be employed as vacuum ion gauge. If the CNF films were used for both cathode and anode, there is no significant different in term of breakdown voltage of air, however, the voltage fluctuation increased to about 10%. The gas ionization device is very robust even after more than 1 month of repeated operations and with no signs of degradation.