Abstract
In industrial applications and environmental monitoring, amperometric gas sensors are very useful for detecting H2 and toxic gases. Expanded polytetrafluoroethylene (ePTFE) membrane was modified by high-energy ion beam irradiation to improve its gas sensitivity. The membrane was irradiated with N and Kr ion beams at energies of 5 MeV/nucleon and 4 MeV/nucleon, respectively, at fluences ranging from 1×1012 to 1×1013 ions/cm2. The energy loss of irradiated ions was simulated by the stopping and range of ions in matter. The irradiated ePTFE surfaces were characterized by field-emission scanning electron microscopy and Raman spectroscopy. The characteristic currents for H2 and toxic gases were measured by sensors equipped with non-irradiated and irradiated membranes. Chemical bonds were broken and the pore size increased with increasing fluences. The characteristic currents for H2 and toxic also increased with increasing fluences. The CO gas sensitivity of N-irradiated ePTFE reached a maximum of only 212%. Meanwhile, Ig/I0 for CO sensing was significantly enhanced by Kr-irradiation at a fluence of 5×1012 ions/cm2. This is due to the porous and amorphous structure on the membrane surface induced by ion beam irradiation. Thus, heavy ion irradiation was effective for improving gas sensitivity.
