TECHNICAL FIELD
[001] The present disclosure described herein, in general, relates to an instrument for the sterilization of medical devices used in surgery. More particularly, the present invention relates to the use of mixture of ozone with oxygen for the sterilization of surgical devices and materials in an airtight instrument with automation.
BACKGROUND
[002] Various materials and devices like surgical kits, different types of fiber optics, fabrics, balloon catheters, stents and plastic tips which are reused in the surgical procedures required sterilization. If these are not completely sterilized then this may cause secondary infection to the patients.
[003] Sterilization is the process to kill various types of fungus, bacteria, virus or other micro-organisms either in their vegetative state or in the dormant state.
[004] The prior methods used for the sterilization are use of combination of steam and dry heat, use of alcohols, use of toxic chemicals like ethylene oxide alone in combination with Freon-12 or detergents, use of ultrasonication excitation, use of flame, use of plasma discharge, exposing materials to high energy electron beam and UV/Gamma radiations
[005] European patent number EP0218003A1, illustrates sterilization of packaged medical devices by using radiations. The process required wrapping of medical device with permeable sterile bag and prior sterilization by radiations.
[006] US patent number US5451368A, describe the process and apparatus for dry sterilization of medical devices and materials. The apparatus used for sterilizing articles is a gas-confining chamber constructed and arranged for containing an electrical discharge.
[007] US patent number US7575715B2, about the methods for sterilizing medical devices using a hydrogen surface-mixed diffusion flame that produces free radicals for the sterilization.
[008] The above-mentioned prior art using process for sterilization are having various drawbacks like use of hazardous chemicals and radiations, use of long time for sterilization, costly and not the user friendly.
[009] The prior art methods and system also having disadvantages like disposing and removal traces of reagents used in sterilization.
[0010] Our invention using the mixture of ozone and oxygen with combination of UV radiations for the sterilization of expensive surgical and medical devices/materials, the instrument is reliable, efficient, easy to operate and maintain as well as user friendly. The used ozone is taken to ozone destructor where it is converted to oxygen.
[0011] The present invention is energy saving as well not required high voltage to operate the system. Also, the system is compact not required large space.

BRIEF DESCRIPTION OF THE INVENTION
[0012] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure; however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawings.
[0013] Figure 1 is a schematic illustration of the different views and dimensions of the instrument/system.
[0014] Figure 2 is a schematic illustration of the electronic circuit diagram used in the invention.
[0015] Figure 3 is a schematic illustration of the front view of the invented instrument and its different components.
[0016] Figure 4 represents the onsite prototype to use as sterilization unit.
[0017] The figure depicts an embodiment of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0018] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail.
[0019] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein.
[0020] Disclosed is an instrument or system is based on cold sterilization principle to sterilize the surgical and medical devices and materials. (Different dimensions and views as shown in figure 1).
[0021] In one of the embodiments the technique is using gas-discharge principle to convert atmospheric oxygen to medical grade high purity ozone (O3). Ozone is generated by converting part of the oxygen gas molecules O2 within a gap formed between two electrodes. When applying an alternating high voltage to the high voltage electrode, micro-discharges will take place in the discharge gap which will dissociate the oxygen molecules. Some of the free oxygen atoms (O) will recombine with the remaining oxygen molecules O2 to form ozone O3. This principle is usually called "Silent Electrical Discharge".
[0022] In one of the embodiments, total control of an optimum concentration of ozone is made possible to sterilize equipment under ambient temperature without any health or environmental or equipment hazard.
[0023] In another embodiment the process is using UV radiations in combination with ozone as well.
[0024] In one of the embodiments the system is using automatic microprocessor-based system to regulate and monitor the air flow rate and concentrations of radiations.
[0025] Referring now to Figure 3, illustrates the front view of designed instrument with it’s attached component. In one of the embodiments the instrument is made up of SS-316 enclosure with desktop design and consist of one box hermetically divided inside into two units by a metal partition. The right side of the unit contains all pneumatic & electrical part, electronics, & appliances for sterilization progress monitoring & safe functioning of the unit. The left side is for the sterilization chamber which is an air-tight casing being hermetically closed by the front door (105) with special internal hinges (101), using a special clamp-handle (102). Inside the sterilization chamber, in a protective metal casing with an Ozone injecting nozzle & bactericidal UV radiation lamp. Special removable perforated trays (104) are provided inside the chamber to facilitate cleaning of the chamber, & washing. The base of the instrument is supported by adjustable four legs (103). The right-side unit consist of digital display (107), ozone generator (108) with front door to control the electronic operations and another side door (106) for maintenance of instrument.
[0026] In another embodiments, the system also containing other major components as shown in figure 2, are as followed:
PRE-FILTER:
The air pre-filter is made up of an efficient Ceramic media to filter out any contamination in the air. The incoming air is passed through this filter to remove dust, impurities or any suspended matter.
MACHINE TIMER
For Operating the machine as per timed mode, factory preset timer is installed in the machine which doses Ozone gas inside the chamber for stipulated time. Further after Ozone Cycle Ozone destruction cycle is operated so as to remove Ozone inside the chamber making it safe to open.
MACHINE RUN DISPLAY
To show the machine test is under process, LCD Backlit display is installed on the front panel of the machine, this display has a countdown timer which shows the leftover time for the test.
HIGH FREQUENCY/ VOLTAGE SUPPLY SYSTEM
A High Voltage/frequency card is used to develop 3-4 K Volts on single-phase AC supply. The high voltage is applied between the electrodes of the Ozone Cells to develop a Corona discharge through which the dried air is passed. Due to this Corona requisite power required for generation of Ozone is applied & ozone is thus produced.
OZONE CELL
The Ozone Generator uses a Corona Discharge Ozone Cell made up of Stainless-Steel electrode and Quartz dielectric. A high voltage is applied between the electrodes, which is generated by a High Voltage. The dry oxygen rich air is fed at one end of the Ozone Cell and the outgoing gas from the Cell is Ozone rich. The cells are forced air-cooled.
POWER FUSE
This fuse protests the Power System and other components from any damage by short-circuiting or over current run. This fuse is mounted on the back side of the cabinet
POWER CORD
Single Phase AC supply is connected to the Device with the help of 3Ø Wire, the connection is on the back side of the cabinet.
CABINET COOLING FAN
For Cooling the Ozone Cell and other components in the cabinet a 105 CFM Ventilation Fan is provided on right side of the Cabinet.
INDICATORS
Following Indicators and LED lamps are provided for long life at the Control Panel for control, indication and fault annunciation.
? Machine Running Display
? Sterilization Cycle ON
[0027] In another embodiment the system using architecture which is pluggable with multiple heterogenous environment.
[0028] In one of the embodiments, the total dimensions of the instrument (Width X Depth X Height, in mm) ranges 500 to 1000 X 200 to 500 X 200 to 500, the internal dimensions of the instrument (Width X Depth X Height, in mm) ranges 200 to 800 X 200 to 500 X 200 to 500, may varies according to the requirements of the user.
[0029] In another embodiment, the sterilization volume ranges 30 to 100 Lit, sterilization cycle time ranges 30 to 120 minutes, workable volume ranges 25 to 50 Lit, temperature inside the sterilization chamber ranges 30 to 45°C, gross weight ranges 15-25 Kgs, nominal ozone concentrations range 6 to 10 %w/w, nominal feed pressure ranges 0.005 to 0.075 Kg/cm2g, full load current ranges 0.5 to 0.6 Amp and main voltage ranges alternative current (AC) 200 to 240V/50Hz ( needs to be connected to the mains via uninterruptible power supply) with a reliable AC voltage regulator having power not less than 100 W.
[0030] In one of the embodiments, the instrument is operated in the following environmental conditions: the ambient temperature for operation ranges 5 to 45°C (with 24 hrs. average =40°C), air humidity ranges 65% to 85% relative humidity and installation must be in the vibration free environment.
[0031] In another embodiments, the instrument will reach nominal production and sterility only after about 30 to 90 minutes.
[0032] In one of the embodiments, the invented instrument is designed to generate air or oxygen ozone gas mixture suitable to sterilize all types of parts & equipment, for example: Thermally-Sensitive materials, Corrosion-resistant metals & alloys (SS, Aluminum, Titanium, etc.), Plastics Products (Fluoroplastics, Propylene, PVC, PU, PE, PC, etc.), Ozone-resistant rubbers (Viton, Silicone, Neoprene, etc.), Polymers, Epoxy resins & Glass.
[0033] In another embodiments, the sterilization efficacy study and bacteriological qualitative sterilization efficacy test for the invented instrument was done as per guidelines of ASTM: E1837-96(2007). Following test solution and media are used for the study: Soyabean Casein Digest Agar, Lot No.0000293928, HiMedia, Phosphate buffer saline, Soyabean Casein Digest Broth, Lot No.0000276125, HiMedia, Cetrimide Broth, Lot No.0000232273, HiMedia, Cetramide Agar, Lot No.0000203363, HiMedia, Cooked Meat Medium, Lot No.0000219703, HiMedia, Baird Parker Agar, Lot No.0000217647, HiMedia, Mackonkey broth, Lot No.0000296450, HiMedia, Mackonkey Agar, Lot No.0000201344, HiMedia. The surgical instruments used in the study for sterilization cycle through invented instrument are devices made of corrosion-resistant metal and alloys- SS, scissor, SS surgical blade, SS forceps. SS bone cutter, SS scalpel, instruments made of plastic- propylene (I. V. Cannula), ozone resistant medical rubber- latex gloves, silicone, polymer- epoxy resins and pathology devices- glass slide, dice from pathology lab. The microorganisms used in the sterilization efficacy study are aerobic bacteria: Escherchia coil (ATCC 8739), Salmonella typhimurium (ATCC 23564), anaerobic bacteria: Clostridium sporogenes (ATCC 19404) and fungus: Aspergillus niger (ATCC 9642). The microorganisms used in the qualitative sterilization efficacy test includes Staphylococcus aureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 9027) and coliform bacteria: Escherchia coil (ATCC 8739).
[0034] In one of the embodiments, the following procedure used to evaluate the efficacy of the invented instrument:
Sterilization efficacy study: One surgical instrument from each category was taken and inoculated with 108 cfu/ml of each tested microorganisms (Escherchia coli, Salmonella typhimurium, Clostridium Sporogenes, Aspergillus niger and Candida albicans). The concentration of microorganism used for the studies was validated by plate count method. The inoculated surgical instrument was placed in the invented instrument and the door of the instrument was closed properly. The cycle was run in the instrument for a period of 70 minutes. After completion of the sterilization cycle the respective instrument was immersed into the phosphate buffer saline (PBS) and further enumeration of the tested microorganisms was determined by plate count method. The plates of bacterial cultures were incubated at 32°C for 48 hours and Fungal at 22°C for 96 hours. After incubation, colonies on the plate were counted and calculated as cfu/ml. Similarly, other categorized instruments were subjected to above mentioned procedure.
Qualitative sterilization efficacy study: One surgical instrument from each category was taken and inoculated with 108 cfu/ml of each tested microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa and Coliform bacteria- Escherichia coli). The concentration of microorganism used for the study was individually validated by plate count method. The inoculated surgical instrument was placed in the invented instrument and the door of the instrument was closed properly. The cycle was run in the instrument for a period of 70 minutes. After completion of the sterilization cycle the respective instrument was immersed into the respective pre-enriched media and after incubation streaked onto the selective media and observed for the detection of the microorganisms.
a) Detection of S. aureus: The inoculated instrument was immersed in Cooked Meat Medium and incubated for 24 hrs. at 37°C. After incubation it was further streaked on Baird Parker Agar and incubated for 30 hrs. at 37°C. Black colonies with grey margin indicates that S. aureus is detected.
b) Detection of P. aeruginosa: The inoculated instrument was immersed in Cetrimide Broth and incubated for 24 hrs. at 37°C. After incubation it was further streaked on Cetrimide Agar and incubated for 24 hrs. at 37°C. Green fluorescent colonies indicate that P. aeruginosa is detected.
c) Detection of Coliform bacteria (E. coli): The inoculated instrument was immersed in Mac Conkey Broth and incubated for 24 hrs. at 37°C. After incubation it was further streaked on Mac Conkey Agar and incubated for 24 hrs at 37°C. Pink colonies indicate that Coliform bacteria (E. colI) is detected.
Similarly, other categorized instruments were subjected to above mentioned procedure.
Positive control: Surgical instrument was inoculated with 108 cfu of Staphylococcus aureus, Escherchia coil, Salmonella typhimurium, Pseudomonas aeruginosa, Clostridium Sporogenes, Aspergillus niger and Candida albicans, but not subjected to invented instrument for the sterilization purpose.
Negative control: The surgical instruments was subjected to the invented instrument but not inoculated with microorganisms.
Med test for the sticker (confirmation of the sterilization completion with color change): Marking on indicator sticker as per the five different locations (Cl, C2, C3, C4 and M) in the upper shelf (104) and lower shelf (104) of invented instrument.
Where, C1- Back left corner, C2- Back right corner, C3- Front left corner, C4- Front right corner, M- Middle
Sterilization cycle was carried out at 70 minutes. After completion of cycle, door was opened and indicator stickers were removed from the sterilizer, Observations were recorded for the change in the color of the indicator sticker
Negative control- indicator sticker not exposed to sterilization
[0035] In another embodiment the acceptance criteria used for the completion of sterilization cycle through using invented instrument are as followed:
Efficacy study: Negative control- no evidence of microbial growth should be observed, Positive control- microbial growth should be found and Test sample- no evidence of microbial growth should be observed.
Med test for the sticker: Negative control- no color change in sticker should be observed and Test sample- sticker color change should be observed.
[0036] The table 1 represents the sterilization efficacy study with corrosion-resistant metal and alloys.

Table 1: The sterilization efficacy study for SS scissor, SS surgical blade, SS forceps
Category Test
Microorganisms Initial Count (cfu/ml) Final Count, after sterilization (cfu/ ml) Efficacy
(%)
SS scissor E. coli 2.4 x108 Less than 1 99.99
S. typhimurium 3.0 x108 Less than 1 99.99
Cl. sprogenes 1.8 x108 Less than 1 99.99
A. niger 2.2 x108 Less than 1 99.99
C. albicans 2.6 x108 Less than 1 99.99
SS surgical blade E. coli 3.2 x108 Less than 1 99.99
S. typhimurium 2.5 x108 Less than 1 99.99
Cl. sprogenes 2.0 x 108 Less than 1 99.99
A. niger 1.8 x108 Less than 1 99.99
C. albicans 2.3 x108 Less than 1 99.99
SS forceps E. coli 3.5 x108 Less than 1 99.99
S. tyhimurium 2.9 x108 Less than 1 99.99
Cl.sprogenes 2.1 x108 Less than 1 99.99
A. niger 1.9 x108 Less than 1 99.99
C. albicans 2.5 x108 Less than 1 99.99

[0037] Table 2 represents the qualitative sterilization efficacy studies for SS scissor, SS surgical blade, SS forceps
Table 2: Qualitative sterilization efficacy studies for SS scissor, SS surgical blade, SS
forceps
Category Test
Microorganisms Intial
Count cfu / ml Result, after sterilization Interpretation
SS scissor S. aureus 2.5 x108 Not Detected Complete removal
P. aeruginosa 3.0 x108 Not Detected Complete removal
Coliform bacteria 2.8 x108 Not Detected Complete removal
SS surgical blade S. aureus 2.7 x108 Not Detected Complete removal
P. aeruginosa 3.2 x108 Not Detected Complete removal
Coliform bacteria 2.5 x108 Not Detected Complete removal
SS forceps S. aureus 2.8 x108 Not Detected Complete removal
P. aeruginosa 2.2 x108 Not Detected Complete removal
Coliform bacteria 3.4 x108 Not Detected Complete removal

[0038] In one of the embodiments, similar results are also obtained for the other materials like SS bone cutter, SS scalpel, instruments made of plastic- propylene (I. V. Cannula), ozone resistant medical rubber- latex gloves, silicone, polymer- epoxy resins and pathology devices- glass slide, dice from pathology lab.
[0039] The positive control tests provide more than 80% recovery for all the microorganisms.
[0040] In another embodiments, the med test for the sticker showed color changes at all locations on the shelfs (104). The also confirmed the complete sterilization provided by the instrument at the given sterilization cycle.
[0041] In one of the embodiments, sterilization cycles are run in the developed instrument for a period of 70 minutes for 30 or 45 Liters & 110 to 155 minutes for 125 Liters.
[0042] In another embodiments, the instrument also used vacuum for the its better sterilization efficiency.
EXAMPLE 1
[0043] In one of the embodiment, the instrument with overall external dimensions (490 X 335 X 305 mm) and internal dimensions (395 X 295 X 290 mm) contained sterilization volume ranges 30 Lit, sterilization cycle time 70 minutes, workable volume ranges 30 Lit, temperature inside the sterilization chamber ranges 37°C, gross weight ranges 18 Kgs, nominal ozone concentrations range 8 %w/w, nominal feed pressure ranges 0.050 Kg/cm2g, full load current ranges 0.5 Amp and main voltage ranges alternative current (AC) 220V/50Hz.

CLAIMS:

1. A sterilization equipment/assembly comprising:
a. one box hermetically divided inside into two units by a metal partition;
b. prefilters;
c. machine timer and run display;
d. High frequency/voltage supply system;
e. Ozone cell;
f. UV lights;
g. Power cord and power fuse;
h. Cabinet cooling fan;
i. Automatic microprocessor-based system; and
j. Indicators
2. The sterilization assembly as claimed in claim 1 wherein the box is made up of stainless steel.
3. The sterilization assembly as claimed in claim 2 wherein the one unit of box is an air-tight casing being hermetically closed by the front door (105) with special internal hinges (101), using a special clamp-handle (102); also containing removable perforated trays (104).
4. The sterilization assembly as claimed in claim 2 wherein the other unit of box consisting digital display (107), ozone generator/cell (108) with front door to control the electronic operations and another side door (106) for maintenance of instrument.
5. The sterilization assembly as claimed in claim 1 wherein the Ozone cell containing Ozone Generator which further uses a Corona Discharge Ozone Cell made up of Stainless-Steel electrode and Quartz dielectric.
6. The sterilization assembly as claimed in claim 1 wherein the sterilization effect is due to the combination of UV radiations and ozone.
7. The sterilization assembly as claimed in claim 1 wherein the assembly is operated at the ambient temperature in range of 5 to 45°C (with 24 hrs. average =40°C) and at 65% to 85% relative humidity.
8. The sterilization assembly as claimed in claim 1 wherein the instrument will reach nominal production and sterility within 30 to 90 minutes.
9. The sterilization assembly as claimed in claim 1 wherein the instrument is used to sterilize all types of parts & equipment, for example: Thermally-Sensitive materials, Corrosion-resistant metals & alloys (SS, Aluminum, Titanium, etc.), Plastics Products (Fluoroplastics, Propylene, PVC, PU, PE, PC, etc.), Ozone-resistant rubbers (Viton, Silicone, Neoprene, etc.), Polymers, Epoxy resins & Glass etc.; most preferably surgical devices and materials.
10. The sterilization assembly as claimed in claim 1 wherein the instrument is sterilizing devices o materials under ambient temperature without any health or environmental or equipment hazards.