The antibacterial activity of gas discharge plasma has been studied for quiet some time. However, high biofilm inactivation activity of plasma was only recently reported. Studies indicate that the etching effect associated with plasmas generated represent an undesired effect, which may cause live bacteria relocation and thus contamination spreading. Meanwhile, the strong etching effects from these high power plasmas may also alter the surface chemistry and affect the biocompatibility of biomaterials. In this study, we examined the efficiency and effectiveness of low power gas discharge plasma for biofilm inactivation and removal. Among the three tested gases, oxygen, nitrogen, and argon, discharge oxygen demonstrated the best anti-biofilm activity because of its excellent ability in killing bacteria in biofilms and mild etching effects. Low power discharge oxygen completely killed and then removed the dead bacteria from attached surface but had negligible effects on the biocompatibility of materials. DNA left on the regenerated surface after removal of biofilms did not have any negative impact on tissue cell growth. On the contrary, dramatically increased growth was found for these cells seeded on regenerated surfaces. These results demonstrate the potential applications of low power discharge oxygen in biofilm treatments of biomaterials and indwelling device decontaminations.

Although avalanche amorphous selenium (a-Se) is a very promising photoconductor for a variety of imaging applications, it is currently restricted to applications with electron beam readout in vacuum pick-up tube called a High-gain Avalanche Rushing Photoconductor (HARP). The electron beam readout is compatible with high definition television (HDTV) applications, but for use in solid-state medical imaging devices it should be replaced by an electronic readout with a two-dimensional array of metal pixel electrodes. However, due to the high electric field required for avalanche multiplication, it is a technological challenge to avoid possible dielectric breakdown at the edges, where electric field experiences local enhancement. It has been shown recently that this problem can be overcome by the use of a Resistive Interface Layer (RIL) deposited between a-Se and the metal electrode, however, at that time, at a sacrifice in transport properties.Here we show that optimization of RIL deposition technique allows for electroded avalanche a-Se with transport properties and time performance previously not achievable with any other a-Se structures. We have demonstrated this by detailed analysis of transport properties performed by Time-of-Flight (TOF) technique. Our results showed that a stable gain of 200 is reached at 104 V/μm for a 15-μm thick a-Se layer, which is the maximum theoretical gain for this thickness. We conclude that RIL is an enabling technology for practical implementation of solid-state avalanche a-Se image sensors.