Plasma pressure pulse sterilization

Claim 2

A process for sterilizing an article having at least one aperture therein, in a plasma reactor, and without gas flow passing unidirectionally through said aperture comprising the steps of: supplying a reactant gas appropriate for plasma generation; varying pressure of said reactant gas within said plasma reactor up and down in a cycle over a prescribed range, each said cycle comprising a pressure-rise interval less than 60 seconds and a pressure-fall interval longer than and following each pressure-rise interval; energizing a plasma reactor generator during at least the pressure-rise interval to create active species for sterilization; and continuing for a sufficient time such that a contaminant on said article has a very low probability of survival.

Claim 3

A process for sterilizing at least one article having a blind aperture therein, comprising the steps of: placing said article in a plasma reactor so as to be in contact with a plasma subsequently formed therein; evacuating said reactor after said article is placed therein; supplying a reactant gas at a pressure less than atmospheric appropriate for plasma generation; varying pressure of said reactant gas within said plasma reactor up and down in a cycle over a prescribed range less than atmospheric, each said cycle comprising a pressure-rise interval less than about 60 seconds and a pressure-fall interval longer than and following said pressure-rise interval; energizing a plasma generator during at least the pressure-rise interval to create active species for sterilization which penetrate said blind aperture; and continuing for a sufficient time such that a contaminant on said article and in said blind aperture has a very low probability of survival.

Claim 4

A process for sterilizing at least one article having a blind aperture therein, comprising the steps of: placing said article in a plasma reactor so as to be in contact with a plasma subsequently formed therein; evacuating said reactor after said article is placed therein; supplying a reactant gas at a pressure less than atmospheric appropriate for plasma generation; varying pressure of said reactant gas within said plasma reactor up and down in a cycle over a prescribed range less than atmospheric, each said cycle comprising a pressure-rise interval less than about 60 seconds and a pressure-fall interval longer than and following said pressure-rise interval; energizing a plasma generator during at least the pressure-rise interval to create active species for sterilization which penetrate said blind aperture; and continuing for a sufficient time such that a contaminant on said article and in said blind aperture has a very low probability of survival.

Claim 5

The process of claim 1 or 2 wherein said plasma generator is additionally energized during at least one pressure-fall interval.

Claim 6

The process of claim 3 wherein said plasma generator is energized during sufficient pressure-rise and pressure-fall intervals to heat said article to a predetermined temperature, and thereafter de-energized during at least one pressure-fall interval to conserve energy and limit further heating of said article.

Claim 7

The process of claim 4 wherein said reactant gas contains oxygen.

Claim 8

The process of claim 1 or 2 wherein said prescribed range has a lower pressure limit P 1 >0.05 Torr (6.7 Pa) and upper pressure limit P 2 given by a relation P 2 /P 1 >L/d where L is an effective interior length of an aperture and d is an effective diffusion length for said active species.

Claim 9

The process of claim 1 or 2 wherein said prescribed range has an upper pressure limit P 2 <100 Torr (13.3 kPa) and lower pressure limit P 1 given by a relation P 2 /P 1 >L/d where L is an effective interior length of an aperture and d is an effective diffusion length for said active species.

Claim 10

The process of claim 1 or 2 wherein said pressure-rise interval is less than about 10 seconds, and said pressure-fall interval is longer than said pressure-rise interval.

Claim 11

The process of claim 8 wherein said pressure-rise interval is less than 10 seconds, and said pressure-fall interval is longer than said pressure-rise interval.