# US 10,441,672 B2 · Apparatus and method for detecting moisture in a vacuum chamber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,672 B2 - Document ID: US10441672B2 - Status: Granted - Kind: B2 - Application number: 15/139,032 - Filed: 2016-04-26 - Published: 2017-10-26 - Granted: 2019-10-15 - Earliest claimed: 2016-04-26 - Assignees: Asp Global Manufacturing GmbH - Applicants: Ethicon, Inc. - Inventors: Doug Vo Truong; Todd Morrison - Web page: https://patentgrep.com/patent/US10441672B2 ## CPC - A61L 2/24: Apparatus using programmed or automatic operation - A61L 2/00: Disinfection or sterilisation of materials or objects, in general; Accessories therefor - A61L 2/208: Hydrogen peroxide - A61L 2/28: Devices for testing the effectiveness or completeness of sterilisation or disinfection, e.g. indicators which change colour - G01N 33/18: Water - A61L 2202/14: Means for controlling sterilisation processes, data processing, presentation and storage means, e.g. sensors, controllers, programs - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method of sterilizing medical instruments using a vacuum chamber connected to reservoir by a valve in a closed state is disclosed that includes placing instruments in a non-sterile state into a sterilization pack, opening a chamber, placing the pack into the chamber, closing the chamber, withdrawing a first volume of air from the chamber, changing a volume of liquid water into vapor, opening the valve, introducing sterilant into the chamber, introducing a second volume of air into the chamber, opening the chamber, removing the pack from the chamber, and removing the instruments in a sterile-state from the pack. The process may further include the steps of repeatedly determining pressure within the chamber, calculating second-derivative values of pressure with respect to time, and determining whether any local maxima exist in a plot of second derivative values that correspond to pressures above and/or below the triple-point pressure of water. ## Claims ### Claim 1 A method of operating a sterilization system having a vacuum chamber for sterilizing instruments, comprising: (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, a first second-derivative value of pressure with respect to time; (e) calculating, with the digital computer, a second second-derivative value of pressure with respect to time, the second second-derivative value corresponding to a time subsequent to the time corresponding to the first second-derivative value; (f) determining, with the digital computer, that the second second-derivative value is greater than the first second-derivative value; and (g) in response to determining that the second second-derivative value is greater than the first second-derivative value, automatically introducing a second volume of air into the chamber. ### Claim 2 (depends on 1) The method of claim 1 wherein the step of repeatedly determining the pressure includes repeatedly taking pressure measurement data and storing the data in a non-transitory storage medium of the digital computer. ### Claim 3 (depends on 2) The method of claim 2 further comprising determining, with the digital computer, that the second second-derivative value occurs at a pressure less than approximately the triple-point pressure of water. ### Claim 4 (depends on 3) The method of claim 3, wherein the step of automatically introducing air into the chamber includes automatically opening a valve. ### Claim 5 (depends on 4) The method of claim 4 further comprising automatically opening the chamber after completing the step of automatically introducing the second volume of air into the chamber. ### Claim 6 (depends on 5) The method of claim 5 further comprising closing the chamber, wherein the step of initiating the timer occurs after the step of closing of the chamber. ### Claim 7 (depends on 6) The method of claim 6 wherein the step of withdrawing a first volume of air from the chamber begins after the step of initiating the timer. ### Claim 8 (depends on 7) The method of claim 7 wherein no sterilant is introduced into the vacuum chamber. ### Claim 9 (depends on 1) The method of claim 1 further comprising the step of determining that the difference between the second second-derivative value and the first second-derivative value is greater than a noise floor. ### Claim 10 A method of operating a sterilization system having vacuum chamber for sterilizing instruments, comprising: (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, a first second-derivative value of pressure with respect to time; (e) calculating, with the digital computer, a second second-derivative value of pressure with respect to time, the second second-derivative value corresponding to a time subsequent to the time corresponding to the first second-derivative value; (f) determining, with the digital computer, that the second second-derivative value is greater than the first second-derivative value; and (g) in response to determining that the second second-derivative value is greater than the first second-derivative value, automatically introducing energy into the chamber. ### Claim 11 (depends on 10) The method of claim 10 wherein the step of repeatedly determining the pressure includes repeatedly taking pressure measurement data and storing the data in a non-transitory storage medium of the digital computer. ### Claim 12 (depends on 11) The method of claim 11 further comprising determining, with the digital computer, that the second second-derivative value occurs at a pressure greater than approximately the triple-point pressure of water. ### Claim 13 (depends on 12) The method of claim 12 wherein the step of introducing energy to the chamber includes at least one of automatically heating the chamber, automatically opening a valve to introduce air into the chamber that is warmer than the chamber, and automatically generating a plasma. ### Claim 14 (depends on 13) The method of claim 13 further comprising closing the chamber, wherein the step of initiating the timer occurs after the step of closing of the chamber. ### Claim 15 (depends on 14) The method of claim 14 wherein the step of withdrawing the first volume of air from the chamber begins after the step of initiating the timer. ### Claim 16 A method of operating a sterilization system having vacuum chamber for sterilizing instruments, comprising: (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, a first second-derivative value of pressure with respect to time; (e) calculating, with the digital computer, a second second-derivative value of pressure with respect to time, the second second-derivative value corresponding to a time subsequent to the time corresponding to the first second-derivative value; (f) determining, with the digital computer, that the second second-derivative value is less than the first second-derivative value; and (g) in response to determining that the second second-derivative value is less than the first second-derivative value, automatically introducing a sterilant gas into the chamber. ### Claim 17 (depends on 16) The method of claim 16 wherein the step of repeatedly determining the pressure includes repeatedly taking pressure measurement data and providing the data to a non-transitory storage medium of the digital computer. ### Claim 18 (depends on 17) The method of claim 17 further comprising maintaining a sterilization-appropriate pressure within the chamber. ### Claim 19 (depends on 18) The method of claim 18 wherein the sterilization-appropriate pressure is maintained for at least one second. ### Claim 20 (depends on 19) The method of claim 19 wherein the sterilization-appropriate pressure is between approximately 4 torr and approximately 0.1 torr. ### Claim 21 (depends on 20) The method of claim 20 wherein the sterilization-appropriate pressure is approximately 0.3 torr. ### Claim 22 (depends on 19) The method of claim 19 wherein the step of automatically introducing the sterilant gas into the chamber occurs after the step of maintaining the sterilization-appropriate pressure for at least one second. ### Claim 23 (depends on 22) The method of claim 22 wherein the step of automatically introducing the sterilant gas into the chamber includes opening a valve. ### Claim 24 (depends on 23) The method of claim 23 further including a step of placing the instruments in a non-sterile state into the chamber and closing the chamber before the step of withdrawing the first volume of air from the chamber. ### Claim 25 (depends on 24) The method of claim 24 further comprising opening the chamber and removing the instruments in a sterile-state from the chamber. ### Claim 26 A method of operating a sterilization system having a vacuum chamber for sterilizing instruments, comprising: (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, second-derivative values of pressure with respect to time; (e) calculating, with the digital computer, a summation of positive differences between consecutive second derivative values; (f) comparing the summation to a threshold value; (g) determining that the summation is greater than the threshold value; and (h) in response to determining that the summation is greater than the threshold value, opening a valve to cause the pressure in the chamber to increase. ### Claim 27 (depends on 26) The method of claim 26 wherein the pressure in the chamber is increased by a second volume of air flowing past the valve and into the chamber. ### Claim 28 (depends on 27) The method of claim 27, wherein the second volume of air flowing into the chamber vaporizes a volume of water. ### Claim 29 A method of operating a sterilization system having a vacuum chamber for sterilizing instruments, comprising: (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, second-derivative values of pressure with respect to time; (e) calculating, with the digital computer, a summation of positive differences between consecutive second derivative values; (f) comparing the summation to a threshold value; (g) determining that the summation is less than the threshold value; and (h) in response to determining that the summation is less than the threshold value, introducing a sterilant into the chamber. ### Claim 30 (depends on 29) The method of claim 29 wherein the summation is a first summation that is terminated when a difference between consecutive second derivative values is negative. ### Claim 31 (depends on 30) The method of claim 30 wherein a second summation is commenced after the first summation is terminated when a difference between consecutive second derivative values is positive.