Sensor device for detecting hydrogen peroxide sterilization process

Abstract

A sensor device having a first electrode and a second electrode. Each of the first electrode and second electrode being electrically coupled to an electrical bridge. The electrical bridge comprises a conductive polymer having a first impedance state and a second impedance state that is different than the first impedance state, and an organic solvent-soluble metal complex.

Description

[0001] SENSOR DEVICE FOR DETECTING HYDROGEN PEROXIDE STERILIZATION

[0002] PROCESS

[0003] Technical Field

[0004] The present invention relates to the field of sensors, and in particular relates to a sensor device for detecting the hydrogen peroxide sterilization process.

[0005] Background

[0006] Vaporized hydrogen peroxide (VHP) is a low temperature sterilization modality, and is being widely used in hospitals for sterilizing the heat and moisture-sensitive medical devices such as plastics, electrical devices, and corrosion-susceptible metal alloys, etc. Due to its dosebased injection mechanism and easy decomposition upon contact to surface, it is difficult to maintain the concentration of hydrogen peroxide through the entire sterilization process.

[0007] Further, different locations within the sterilization chamber and different structure of medical instruments see different concentrations of actual hydrogen peroxide. In some cases, the hydrogen peroxide could drop to near zero when it contacts with some surfaces contaminated by certain metal containing catalyst, such as transition metals. Moreover, the vacuum efficiency of the sterilizer plays a big role on remove the remaining air from plastic surface and / or channels / crevices is extremely important for vaporized hydrogen peroxide to be correctly applied to the surface for effective sterilization. Therefore, monitoring of performance of hydrogen peroxide sterilizer itself such as vacuum, concentration of hydrogen peroxide and the distribution of hydrogen peroxide becomes extremely important, especially at current stage of technology capability which is far from being sophisticated as compared with current steam sterilizer.

[0008] Summary

[0009] Various chemical indicators for sterilization monitoring are described in, for example, U.S. Pat. App. Pub. 2012 / 0100395, U.S. Pat. 3,523,011 and U.S. Pat. 5,064,576. Traditional chemical indicators are based on colorimetric changes in the presence of a certain sterilant and its running conditions such as sterilization temperature or sterilization time. In the current practice of evaluating a chemical indicator visually, a user needs to visually judge the color development to determine if the chemical indicator was subjected to an adequate sterilization process, which can be subjective. As a result, articles and methods for more objectively determining the adequacy of sterilization processes are desirable.

[0010] Previous reports are there to utilize nanoparticles of metals such as copper, silver or modified copper as catalysts in a form of conductive polyaniline system to create a sensor for measuring concentration of hydrogen peroxide vapor; however, the use of metal particles typically necessitate an additional step to achieve dispersion in solutions. Additionally, the interaction between nanoparticles, acting as redox components, and conductive polymers alongside hydrogen peroxide (H2O2) tends to be uneven.

[0011] It would be highly desirable to have sensor device where the redox component interacts with a conductive polymer and a sterilant homogeneously.

[0012] In one aspect, the present disclosure provides sensor device comprising: a first electrode and a second electrode, each of the first and second electrode being electrically coupled to an electrical bridge; the electrical bridge comprising a conductive polymer having a first impedance state and a second impedance state that is different than the first impedance state and an organic solvent-soluble metal complex.

[0013] In another aspect, the present disclosure provides a method, the method comprising exposing the sensor of the present disclosure to a sterilant in a sterilization process.

[0014] Definitions

[0015] For the following defined terms, these definitions shall be applied for the entire Specification, including the claims, unless a different definition is provided in the claims or elsewhere in the Specification based upon a specific reference to a modification of a term used in the following definitions:

[0016] The terms "about" or "approximately" with reference to a numerical value or a shape means + / - five percent of the numerical value or property or characteristic, but also expressly includes any narrow range within the + / - five percent of the numerical value or property or characteristic as well as the exact numerical value. For example, temperature of "about" 100°C refers to temperature from 95 °C to 105 °C, but also expressly includes any narrower range of temperature or even a single temperature within that range, including, for example, a temperature of exactly 100°C.

[0017] The term “substantially” with reference to a property or characteristic means that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited. For example, a substrate that is “substantially” transparent refers to a substrate that transmits more radiation (e.g. visible light) than it fails to transmit (e g. absorbs and reflects). Thus, a substrate that transmits more than 50% of the visible light incident upon its surface is substantially transparent, but a substrate that transmits 50% or less of the visible light incident upon its surface is not substantially transparent.

[0018] “Adequate sterilization process" refers to a sterilization process that achieves a sterility assurance level of 10‘6or 12 log reduction of Bacillus Subtilis var. Niger. The sterility assurance level is related to a probability that a sterilized unit remains nonsterile after undergoing the sterilization process.

[0019] "Adequate environmental condition" refers to environmental conditions inside of a sterilization chamber that correspond to the adequate sterilization process.

[0020] “Closed system” refers to sterilization chamber of the sterilization system from which most other gases have been removed.

[0021] Although the term “impedance” is used, the term “impedance” is the reciprocal of the “admittance”. Depending on the context, either impedance or admittance can be used as changes in the impedance of a material also change the admittance of the material.

[0022] " Second substrate position" refers to a position on the substrate that indicates adequate sterilization. May be established partially by the wicking substrate.

[0023] The phrase "comprises at least one of followed by a list" refers to comprising any one of the items in the list and any combination of two or more items in the list. The phrase "at least one of followed by a list" refers to any one of the items in the list or any combination of two or more items in the list. Although the term “impedance” is used, the term “impedance” is the reciprocal of the “admittance”. Depending on the context, either impedance or admittance can be used as changes in the impedance of a material.

[0024] The term "and / or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0025] All numerical ranges are inclusive of their endpoints and non-integral values between the endpoints unless otherwise stated (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0026] These and other aspects of the present disclosure will be apparent from the detailed description below. In no event, however, should the above summaries be construed as limitations on the claimed subject matter, which subject matter is defined solely by the attached claims, as may be amended during prosecution.

[0027] Brief Description of Drawings

[0028] The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying figures, in which:

[0029] FIG. 1 illustrates a sterilization system that can be used in connection with the sensors of the present disclosure.

[0030] FIG. 2 illustrates a sensor device in accordance with some embodiments of the present disclosure.

[0031] FIG. 3 illustrates use of a sensor device in a sterilization system in accordance with some embodiments of the present disclosure.

[0032] FIG. 4 illustrates use of a sensor device in a sterilization system in accordance with some embodiments of the present disclosure.

[0033] FIG. 5 illustrates a sterilization indicator system in accordance with one embodiment.

[0034] FIG. 6 illustrates a method in accordance with one embodiment.

[0035] While the above -identified drawings, which may not be drawn to scale, set forth various embodiments of the present disclosure, other embodiments are also contemplated, as noted in the Detailed Description. In all cases, this disclosure describes the presently disclosed invention by way of representation of exemplary embodiments and not by express limitations. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of this disclosure.

[0036] Detailed Description

[0037] Before any embodiments of the present disclosure are explained in detail, it is understood that the present disclosure is not limited in its application to the details of use, construction, and the arrangement of components set forth in the following description. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways that will become apparent to a person of ordinary skill in the art upon reading. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

[0038] Unless otherwise indicated, all numbers expressing quantities or ingredients, measurement of properties and so forth used in the Specification and embodiments are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached listing of embodiments can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. In some embodiments, the present disclosure relates to a sterilization system and associated sensor device having a sterilant-responsive switch that may be responsive to environmental conditions (including the presence of a sterilant such as steam) in a sterilization process. Generally, the sensor devices of the present disclosure enable electronical reporting of information (e.g., pass / fail information, accept / reject information) regarding each sterilization cycle to avoid subjective judgements that can lead to errors (e.g., perceived change in color by the human eye). Also, the systems and devices of the present disclosure enable digitalization of sterilization results which, in turn, will free technicians from manual document and physical storage.

[0039] FIG. 1 illustrates a sterilization system 100 in which a sensor device of the present disclosure may be employed. As shown in FIG. 1, the sterilization system 100 may include a chamber 110 into which a sterilant 120 may be directed. The sterilization system 100 may be of a type commonly used by hospitals and other medical facilities to sterilize reusable medical devices and may be used to sterilize reusable medical devices. The sterilization system 100 of the present disclosure is based on hydrogen peroxide (H2O2) as a sterilant (e.g., vaporized hydrogen peroxide). Examples of sterilization systems using hydrogen peroxide as a sterilant are commercially available from Steris (Mentor, OH) or Tuttnauer (Israel).

[0040] In some embodiments, the chamber 110 can have one or more environmental conditions. The environmental conditions can be related to conditions inside the chamber 110 and can include, for example, exposure time, sterilant (presence, concentration of hydrogen peroxide, etc.), temperature, pressure, or combinations thereof. In some embodiments, a first environmental condition can exist pre-sterilization process and a second environmental condition can exist during the sterilization process.

[0041] In some embodiments, the present disclosure is directed to a sensor that is configured to determine whether a sterilization process within a sterilization system is carried out in accordance with a predetermined guideline or whether an adequate sterilization process was achieved. An adequate sterilization process can vary based on the sterilant used, the manufacturer of the sterilizer, or the articles to be sterilized.

[0042] Referring to FIG. 2, a sensor device 130 in accordance with some embodiments of the present disclosure is depicted. The sensor device 130 may include a first electrode 135, a second electrode 140 (sometimes, collectively, referred to as an electrode pair), and a sterilant- responsive electrical bridge 145 which may facilitate electrical communication between the first electrode 135 and the second electrode 140. In some embodiments, each of the first electrode 135 and the second electrode 140 may be in electrical communication, or electrically coupled, (either via physical contact or via an intermediate such as a conductive member (e.g., an electrically conductive wire)) via the sterilant- responsive electrical bridge 145. As shown in FIG. 2, in some embodiments, an end of each of the first electrode 135 and the second electrode 140 may be in physical contact with the sterilant- responsive electrical bridge 145. In some embodiments, absent the sterilant-responsive electrical bridge 145, the electrode pair 135 and 140 may not be capable of electrical communication (i.e., the electrodes are not physically touching or are spaced apart at least a distance such that there is no electrical communication without an intervening conductive member).

[0043] In some embodiments, the first electrode 135 and the second electrode 140 may include a metal such as aluminium, iron, zinc, tungsten, molybdenum, tin, nickel, copper, or alloys thereof, or carbon black, graphene, carbon nanotubes, or a conducting polymer.

[0044] In some embodiments, the electrical bridge 145 may be configured to have a first impedance state (e.g., high impedance / no or low conductivity) and a second impedance state that is markedly different than the first impedance state (e.g., low impedance / high conductivity (or vice versa). For example, in some embodiments, in a first state, the electrical bridge exhibits a low impedance and in a second state exhibits a high impedance (relative to the low impedance state). In some alternative embodiments, in a first state, the electrical bridge exhibits a low electric capacitance and in a second state exhibits a high electric capacitance (relative to the low electric capacitance state) or vice versa.

[0045] In some embodiments, the electrical bridge 145 may include a conductive polymer and an organic solvent-soluble metal complex.

[0046] In other embodiments, the electrical bridge 145 may optionally also include a polymeric binder.

[0047] In some embodiments, the conductive polymer and organic solvent-soluble metal complex may be dispersed in a polymeric binder and deposited onto the electrode pair.

[0048] A conductive polymer can be any substance that has semi -conductive properties or that is switchable between a first state and a second state. In other words, the conductive polymer is capable of being converted from being in the first state to being in the second state when in contact with a sterilant. In at least one embodiment, the first state can be a first impedance state having a first impedance and the second state can be a second impedance state having a second impedance, for example, a solid substance that has conductivity between that of an insulator and a metal. In at least one embodiment, the impedance state can be related to the impedance and the admittance of the sensor device. The impedance state can be related to an opposition to flow of the conductive polymer and include aggregation of its resistance, and inductive and capacitive reactance. In at least one embodiment, the first state can be a non-conductive state and the second state can be a conductive state and vice versa. The conductive state can be a doped conductive state and the non-conductive state can be a non-conductive reduced form or a non-conductive oxidized form of the conductive polymer. In at least one embodiment, the conductive polymers may be in forms of conductive polymer electrolytes, for example, protonated forms.

[0049] In some embodiments, the conductive polymer can have a repeat unit of aniline, acetylene, pyrrole, phenylene, phenylene vinylene, phenylene ethynylene, phenylene sulfide, fluorene, pyrene, azulene, naphthalene, carbazole, indole, thiophene, ethylene dioxythiophene, or combinations thereof. The conductive polymer can be doped or undoped with various dopants such as dinonylnaphthalene sulfonic acid (DNNSA), dodecylbenzenesulfonic acid (DBSA), arsenic pentafluoride, triiodide, camphorsulfonate, methanesulfonic acid, halogens or polyhalogen ions, methanol, hydrogen sulfate, hydrochloric acid, tetrafluoroborate, sodium sulfite, or combinations thereof.

[0050] In some embodiments, the conductive polymer may be present in an amount of at least 5 wt. %, at least 10 wt. %, at least 30 wt. %, at least 50 wt. %, or at least 90 wt. %, based on the total weight of the composite or the blend material that forms the electrical bridge 145.

[0051] In some embodiments, the conductive polymer may include polyacetylene, polyaniline (PANI) or polypyrrole.

[0052] In a preferred embodiment, the conductive polymer includes polyaniline (PANI).

[0053] In some embodiments, the conductive polymer of the present disclosure may be present initially, in the conductive emeraldine salt form (acid form) and be convertible to the nonconducting emeraldine form (base form) upon exposure to a sterilant.

[0054] In some embodiments, the conductive PANI is in a form of electrolytes, polyelectrolytes or PANI salts which can be readily achieved by acid-doping of PANI. The emeraldine can be non-conductive in the base form and conductive in the polyelectrolyte form or the salt form. The emeraldine salt can be converted into the leucoemeraldine salt or per(nigraniline) which are non-conductive, via a redox reaction. The conductive polymer can be converted to non-conductive polymer via a de-doping reaction.

[0055] Therefore, in some embodiment, the initial impedance state could correspond to a protonated polyaniline (conductive), while the second impedance state could be a nonprotonated polyaniline (non-conductive), and vice versa.

[0056] In an embodiment, the conductive polymer may comprise polyaniline which is dissolved in solvents to form Polyaniline (PANI coating solution). The solvents may include such as xylene, methyl isobutyl ketone, p-toluenesulfonyl isocyanate, aliphatic polyisocyanate such as Desmodur ® n3390 and poly caprolactone polyol such as CAPA™ 3031.

[0057] In some embodiments, the composition comprises useful organic solvent-soluble metal complex which can generate electrons, hydrides, hydroxide, or hydrogen upon exposure to a hydrogen peroxide (sterilant). Further, organic solvent-soluble transition metal complex may be characterized as redox particles (i.e., particles that facilitate a chemical reaction in the electrical bridge 145 in the presence of a sterilant that neutralize the protonated conducting polymer (acid form) to a base form through the generation of hydroxide ions from the reaction between the sterilant and the solvent-soluble metal complex.

[0058] In some embodiments, the organic solvent-soluble metal complex may include those that can be activated to generate free electrons, hydrides, or hydrogen to reduce PANI electrolytes or polyelectrolytes (protonated forms) to its leucoemeraldine salt form i.e. which are capable of reducing an electrically conductive polymer from a first conductive state to a second conductive state (e.g., converting PANI from the emeraldine salt (ES) state to the leucoemeraldine salt (LS) state).

[0059] In some embodiments, in the composition comprising an organic solvent-soluble metal complex, the metal or metal ions are present in the form of a coordination complex with ligands.

[0060] In some embodiments, the organic solvent-soluble metal complex may include transition metal or metal ions.

[0061] In some embodiments, transition metals or metal ions comprise ruthenium, iron, osmium, silver, gold, copper or copper (I) complex.

[0062] In some embodiments, ligands comprise carbonyl complex, triphenyl phosphine, or combinations thereof.

[0063] In some embodiments, suitable organic solvent-soluble metal complex may include transition metal complex such as tris(triphenylphosphine) ruthenium (II) dichloride, (ethylecyclopentadienyl)-(triphenylphosphine)copper(I), triirondo decacarbonyl, triruthenium dodecacarbonyl or bromotris(triphenylphosphine)copper (I).

[0064] In a preferred embodiment, suitable organic solvent-soluble transition metal complex may include tris(triphenylphosphine) ruthenium (II) dichloride.

[0065] In some embodiments, the organic solvent may include non-polar solvents, weak polar solvents, medium polar solvents, or combinations thereof. This may include toluene, xylenes, methyl isobutyl ketone, methyl ethyl ketone, methyl propyl ketone, isopentyl methyl ketone, or combination of.

[0066] In some embodiments, an organic solvent-soluble transition metal complex may be present in the electrical bridge 145 in an amount of 0. 1- 10% based on the total weight of the composite material that forms the electrical bridge 145. In some embodiments, as mentioned herein above, an organic solvent-soluble transition metal complex may include those that can be activated by a hydrogen peroxide sterilant to generate free electrons, hydrides, or hydrogen which are capable of reducing a conductive polymer from a first conductive state to a second conductive state (e.g., converting PANI from the emeraldine salt (ES) state to the leucoemeraldine salt (LS) state). Examples of such a set of reactions are shown below (unbalanced equations):

[0067] An example of a mechanism using transition metal complex of tris(triphenylphosphine) ruthenium (II) dichloride is shown below

[0068] Emerakkiie base

[0069] In embodiments that include polymeric binder, the polymeric binder can include any suitable polymeric binder, for example, polyurethane including curable polyurethane, such as 2-part curable polyurethane, a polyvinyl butyral, a polyacrylate, polyvinyl acetate, polystyrene, polystyrene acrylate, a polyurea, a polyimide, an amide, an epoxy, a glycidyl- Si-Zr-containing solgel, a polyester, a phenoxy resin, a polysulfide, polyolefins or mixtures thereof, thermally and photochemically curable acrylic polymers or copolymers.

[0070] In some embodiments, the polymeric binder may be present in the electrical bridge 145 in an amount of at least 5 wt. %, at least 10 wt. %, at least 40 wt. %, at least 50 wt. %, or at least 90 wt. %, based on the total weight of the composite material that forms the electrical bridge 145.

[0071] In a preferred embodiment of the invention, the binder is polyurethane. In some embodiments, in addition to a change in impedance state, the electrical bridge 145 may additionally exhibit a change in color. For example, in embodiments in which the electrical bridge 145 includes PANI, the electrical bridge 145 may begin in a first impedance state having a first color (e g., green) and a second impedance state having a second color (e g., blue or yellow). In this manner, visual determination of the adequacy of a sterilization cycle may be carried out. In some embodiments, the sensor device 130 may be a stand-alone device that can be placed into a sterilization system 100. In further embodiments, the sensor device 130 may be incorporated into another device (e.g., sterilization process challenge device with a torturous path such as porous matrix or a lumen channel, Bowie-Dick test pack, or the like) which may include a housing and one or more internal components or materials that are configured to facilitate assurance that adequate sterilization conditions are present during a sterilization cycle.

[0072] Referring to FIG. 3, use of the sensor device 130 in sterilization system 100 in accordance with some embodiments of the present disclosure is illustrated. As shown, the sensor device 130 may be disposed within the sterilization chamber 110. In some embodiments, the sensor 130 may be disposed within the chamber 110 such that it may interact with the component(s) of the sterilant 120 upon entry into the chamber 110.

[0073] In some embodiments, the device to measure resistance (R), voltage (V) and current (I) may also be provided; wherein electrical resistance is calculated using Ohm's law i.e. R= V / 1. This device can be a reader device 160 and may be configured to receive signals from the sensor device 130 and translate the received signal into a determination that relates to the adequacy of a sterilization cycle (e.g., a pass / fail determination). It may be in electronic communication (or capable of electronic communication) (continuously or at any desired interval) with the sensor device 130 (e.g., wireless communication such as Bluetooth, RF, or Near-Field communication, or wired communication via a suitable electronic connection (e.g., a pair of electrical leads that may be coupled to an electrode pair of the sensor device 130). In some embodiments, the reader device 160 may be a device for measuring electrical resistance (e.g., an electrical multimeter).

[0074] Referring to FIG. 4, use of the sensor device 130 in a sterilization system 100 in accordance with some embodiments of the present disclosure is illustrated. As shown, the sensor device 130 may again be disposed within the chamber 110 of sterilization system 100 such that it may interact with hydrogen peroxide upon entry into the chamber 110. Additionally, one or more medical devices 165 to be sterilized may be disposed with the chamber 110. For example, as shown, the sensor 130 and the one or more medical devices 165 may be housed to together in a package 170 (often referred to in industry as a tray). Each package 170 may house any number of medical devices 165 or sensors 130. Alternatively, the sensor 130 and the one or more medical devices 165 may be housed separately within the chamber 110.

[0075] In some embodiments, the present disclosure further relates to methods of using the sensor 130 in a sterilization system 100. The method may begin with a user placing the sensor 130 in the chamber 110. As previously discussed, the sensor 130 may be placed alone in the chamber 110 or may be placed with one or more medical devices to be sterilized (and may be packaged in a tray with medical devices or disposed in the chamber 110 separate from the medical device or medical device tray). After the sensor is placed in the chamber, the chamber 110 can be sealed from the environment.

[0076] In some embodiments, the user can then activate a sterilization process of the sterilizer and the sensor device can be exposed to hydrogen peroxide and / or one or more environmental conditions in a sterilization process. Various standards for each sterilant can exist and may vary based on the manufacturer, article to be sterilized, or combinations thereof. For example, when the sterilant is hydrogen peroxide, then the sterilant may be in an atmosphere containing at least 30% hydrogen peroxide vapor and the sterilization process may be carried out at least 40 degrees Celsius for at least 60 minutes.

[0077] In some embodiments, exposing the sensor 130 to the sterilant and / or the conditions within the chamber 110, may result in a change of the impedance state of the conductive polymer of the electrical bridge 145.

[0078] In some embodiments, the method may further include continuously, intermittently, or at any desired time, the reader device 160 receiving signals from the sensor device 130 and translating such received signal into a determination that relates to the adequacy of a sterilization cycle (e.g., a pass / fail determination). As discussed above, the received signals may relate to an altered resistance across the electrode pair, which corresponds to various environmental conditions that were or were not achieved in the sterilization process.

[0079] FIG. 5 illustrates a sterilization indicator system 1100. The sterilization indicator system 1100 can include a sterilizer 1104. The sterilizer 1104 is configured to provide a sterilant (hydrogen peroxide) 1108 to a chamber 1112 in a sterilization process. The chamber 1112 can have one or more environmental conditions. In at least one embodiment, the environmental condition can be related to conditions inside of the chamber 1112 and can include, but not limited to, exposure time, sterilant concentration, temperature, pressure, or combinations thereof. For example, a first environmental condition can exist pre -sterilization process and a second environmental condition can exist during the sterilization process. A sensor device 1102 can determine whether the second environmental condition corresponds to an adequate sterilization process. An adequate sterilization process can vary based on the sterilant used, the manufacturer of the sterilizer, and the article 1106 to be sterilized.

[0080] The sterilization indicator system 1100 includes a sensor device 1102 that is capable of collecting and providing data regarding the environmental conditions within chamber 1112 with respect to the sterilization process. Further, the sensor device 1102 can also be read by a sensing device 1110. The sensing device 1110 is an electronic device that can read the environmental conditions remotely. In one example, the sensing device 1110 can read the sensor device 1102 to determine environmental conditions in the chamber 1112 in real-time through the walls of the chamber 1112. For example, a wall can have a hole formed therein for directly reading an RFID tag through the steel wall. In another example, the sensing device 1110 can read / interrogate the sensor device 1102 to determine environmental conditions of the chamber 1112 when outside of the walls of the chamber 1112, e g., when in a wrapped package 1114. In at least one embodiment, an adequate sterilization process can change the electrical impedance of the sensor device 1102 and be detected by the sensing device 1110.

[0081] The sensing device 1110 can use wireless communication or wired communication to read the sensor device 1102. For example, if wired, then the sensor device 1102 can include a memory element to store the environmental conditions captured by the sensor device 1102. In at least one embodiment, the sensor device 1102 can be affected by past environmental conditions and be chemically or electrically modified. For example, the sensor device 1102 can also include a sterilant-responsive switch that indicates, directly or indirectly, the environmental condition from the sterilization process in the chamber 1112.

[0082] The sensor device 1102 can include any type of sterilant-resistant integrated circuit or simple open circuit. The sensor device 1102 can include any appropriate electrical connection to communicate with a sensing device 1110 that detects and measures any electrical signals generated. Such connections may include, but are not limited to, hard wiring, physical electrical contacts, e.g., spring -loaded or jacks, Ethernet, Bluetooth, wireless local area networks (WLANs), WiFi, WiMax and the like, or any other wired or wireless communication type known in the art.

[0083] For example, the sensor device can be an RFID tag, a thermometer, a pressure sensor, a communication device, or combinations thereof. In at least one embodiment, the sensor device 1102 is an RFID tag and the sensing device 1110 is an RFID interrogator device. Example RFID interrogator devices can be based on UHF and commercially available from Zebra (Lincolnshire, IL), Alien Technology (San Jose, CA), or Impinj (Seattle, WA). Other example RFID interrogator device can also be based on High Frequency (HF) and commercially available from Jadak (Syracuse, NY), Technology Solutions Ltd (United Kingdom), Samsung, or Apple or be based on Low Frequency (LF) and commercially available from RFID Inc. (Aurora, CO), Gao RFID Inc. (Ontario, Canada), or Sky RFID Inc. (Ontario, Canada).

[0084] The sensor device 1102 can be paired with one or more components such as a substrate and environmental change receptor to form a sterilization indicator sensor which is described further herein. In at least one embodiment, the environmental change receptor is distinct from the sterilant- responsive switch. For example, the environmental change receptor can be configured to affect the admittance / impedance of the sterilant-responsive switch.

[0085] In at least one embodiment, the article 1106 and sensor device 1102 can be wrapped in a package 1114. The sensor device 1102 can be responsive to the sterilization process occurring in the chamber 1112. The sensor device 1102 can be read as to determine whether the using the sensing device 1110 without unwrapping the package 1114 which helps assure sterility of the article 1106 to an end user.

[0086] FIG. 6 illustrates a method 1500 of using the sensor device. The method 1500 can begin at block 1502. In block 1502, a user can place the sensor device in the chamber of a sterilizer. In at least one embodiment, the user can place the sensor device with an article to be sterilized in the chamber. The user can also package the sensor device and the article in a wrapped package such that the sensor device is not visible while the package is wrapped. The sensor device is described further herein and includes a sterilant-responsive switch. In at least one embodiment, the user can place the sensor device can be a part of a sterilization indicator sensor which can be placed in the chamber. After the sensor device is placed in the chamber, then the chamber can be sealed from the environment.

[0087] In block 1504, a user can activate a sterilization process of the sterilizer and the sensor device can be exposed to a sterilant and / or one or more environmental conditions in a sterilization process. When the sterilant is hydrogen peroxide, then the environmental condition is an atmosphere containing 31% hydrogen peroxide vapor and the sterilization process is 50 degrees C for 60 minutes.

[0088] In block 1506, the sterilant-responsive switch of the sensor device or the sterilization indicator sensor can react with the sterilant or react (physically or chemically) with the environmental condition (which can include the sterilant). In at least one embodiment, the sterilant-responsive switch can also interact with a substrate or an environmental change receptor to modify the admittance / impedance of the sterilant-responsive switch. For example, the environmental condition, environmental change receptor, or combinations thereof, can cause sterilant-responsive switch to change from the first state to the second state, for example, from a first impedance state to a second impedance state, or vice versa. In at least one embodiment, upon exposure to an adequate environmental condition comprising a hydrogen peroxide sterilant, the conductive particle can react with the sterilant and / or conductive polymer to change impedance of the conductive polymer. In at least one embodiment, upon exposure to an adequate environmental condition comprising hydrogen peroxide sterilant, the conductive particle can react with the sterilant first and subsequently react with the conducting polymer to change the impedance of the conductive polymer. In at least one embodiment, upon exposure to an adequate environmental condition comprising hydrogen peroxide sterilant, which can trigger a redox reaction in the sterilant-responsive matrix to change impedance of the conductive polymer.

[0089] In block 1508 through block 1514, a sensing device can be configured to read the sensor device to determine whether the first impedance state is present.

[0090] In at least one embodiment, the sensing device is configured to read the sensor device through a wrapped package. The sensing device can also be configured to read the sensor device when the chamber is sealed (i.e., through a housing of the sterilizer). The sensing device can use an onboard memory to later read the sensor device. In at least one embodiment, the sensing device can be an RFID interrogator device. The sensing device can be configured to transmit a first radio signal to the sensing device in block 1508. The first radio signal can be a variety of frequencies but is preferably UHF (300 MHz-3000 MHz).

[0091] The first radio signal can affect the sensor device and the sensor device can emit a second radio signal or a third radio signal in block 1512, or block 1514. For example, in decision block 1510, if the sterilant-responsive switch was exposed to a sterilization process, for example, an adequate sterilization process, then the sensor device can output a second radio signal in block 1512. If the sensor device was not exposed to an adequate sterilization process, then the sensor device can output a third radio signal in block 1514. In at least one embodiment, the output can be inherent and not require any computational resources of the sensor device. In at least one embodiment, the second radio signal can be indicative of whether the sterilant- responsive switch has degraded (e.g., the sterilant cause degradation of the sterilant-responsive switch directly or indirectly). In at least one embodiment, the second radio signal can be indicative of whether the sterilant-responsive switch completed a circuit of a monitoring loop of the sensor device. The third radio signal can be indicative of no degradation or minimal degradation of the sterilant-responsive switch.

[0092] The presence of the second or third radio signal can indicate to the sensing device whether the sensor device was exposed to environmental conditions from an adequate sterilization process. The sensing device can further communicate whether the adequate sterilization process was achieved and perform subsequent actions as a result.

[0093] In some alternative embodiments, aspects of the present disclosure relate to a sensor device having a sterilant-responsive switch that is responsive to environmental conditions (including sterilant) in a sterilization process. The sterilant-responsive switch can be electrically coupled to conductive traces of the sensor device and can be mechanically activated or formed from a conductive polymer.

[0094] EXAMPLES

[0095] These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise.

[0096] Table: Materials

[0097] Example 1: Solubility determination:

[0098] A small quantity of each solid was added to 20 g of the mix of 1 / 1 MIBK / xylene (w / w) in 40 ml glass vials and allowed to mix on a roller for overnight. Samples were inspected to check the clarity of each solution. For solutions containing insoluble solid, the solution was allowed to pass through a filter paper and dried in fume hood for 3 days to allow the solvent completely evaporated. Filter papers were re-weighed and calculated the actual solid of the paper (need to pre-weight each filter paper before filtration). The resulting solubility was calculated and recorded in the table below.

[0099] Table 1: Solubility of various transition metal complex and performance check for hydrogen peroxide detection

[0100] Example 2: Electrically conductive material

[0101] Composition

[0102] 100 g of mother polyaniline (PANI) coating solution was made as per below table (Table 2) after gently mixing and stored at room temperature overnight. In another glass vial, tris(triphenylphosphine) ruthenium (II) dichloride was dissolved in xylene at 10 wt% by gently mixing the powder and solvent with a magnetic stirring bar overnight. The mother PANI solution was allotted into five 20 ml glass vials with each containing 10 g of PANI coating solution. To each of the glass vials was added a calculated amount of 10% ruthenium complex or xylene shown in Table 3 and vortexed well before coating. A 10% or 5% of copper nanoparticle suspension was also prepared for comparison by adding 0.1% of trifluoropropyl trimethoxysilane in 1 : 1 mix of xylene and MIBK with 2 hours of ultrasonication.

[0103] Table 2: Parent PANI Solution

[0104] Table 3. Test results from H2O2 sterilization cycles with samples prepared from predissolved metal complex solutions.

[0105] Example 3: Construction of the electrically conductive material

[0106] A pre-printed electrode pad pair (5x5 mm pads with 25 mm long legs extended from each pad) with a 2 mm gap in between on PET film was used as substrate to coat the solutions across the two pads using #16 Myers bar. The coated film was then dried at 140°C for 6 minutes. Samples were subject to H2O2 sterilization process on ASP 100 S sterilizer and the resistance values were measured with a multimeter.

[0107] All samples were noticeable for color change from original green to blue except the control samples which did not include a catalyst. The ruthenium complex noticeably showed the highest resistance change after exposure to hydrogen peroxide sterilization process. Subsequently, the solutions were stored at room temperature and watched for stability.

[0108] The ruthenium samples were all coatable and showed the same test results after being sterilized with H2O2. However, the copper NP solutions were all gelled and became not coatable after three days as shown in Table 3..

[0109] Example 4:

[0110] In this experiment, the same mother coating solution was made as described in Example 2. Instead of pre-dissolving metal complexes in toluene or xylene, 50 mg of each metal complex was added directly to 10 g of coating solution and allowed to roll for about 2 hours. The resulting coating solution was then coated with #12 or #24 Meyer bar on the same Ag / C electrode pair printed on a PET film.

[0111] The samples were cut into individual sensor devices and exposed to hydrogen peroxide sterilization on ASP 100S. The resulting samples were measured with a multimeter. Color was also recorded. Results are shown in Table 4.

[0112] Table 4: Test results from H2O2 sterilization cycles with direct mix of powder into coating solution.

Claims

Claims1. A sensor device comprising: a first electrode and a second electrode, each of the first electrode and second electrode being electrically coupled to an electrical bridge; the electrical bridge comprising: a conductive polymer having a first impedance state and a second impedance state that is different than the first impedance state; and an organic solvent-soluble metal complex.

2. The sensor device of claim 1, wherein the electrical bridge is configured such that conductive polymer changes from the first impedance state to the second impedance state in response to a change in one or more environmental conditions.

3. The sensor device of claim 2, wherein the electrical bridge is configured such that conductive polymer changes from the first impedance state to the second impedance state in response to a change in response to exposure to a sterilant.

4. The sensor device of claim 3, wherein the sterilant comprises hydrogen peroxide.

5. The sensor device of claim 1, wherein the sensor to measure impedance measures voltage and current and calculates impedance by Ohm’s law.

6. The sensor device of claim 1, wherein the electrical bridge further comprises a polymeric binder.

7. The sensor device of claim 1 , wherein the organic solvent-soluble metal complex comprises metal or metal ions, present in the form of a coordination complex with ligands.

8. The sensor device of claim 7, wherein the metal or metal ions comprises transition metal or metal ions.

9. The sensor device of claim 8, wherein the transition metal or metal ions comprise ruthenium, iron, osmium, silver, gold, copper or copper (I) complex.

10. The sensor device of claim 7, wherein the ligands comprise carbonyl complex, triphenyl phosphine, or combinations thereof.

11. The sensor device of claim 1, wherein the organic solvent comprises non-polar solvent, weak polar solvents, medium polar solvents or combination of.

12. The sensor device of claim 11, wherein the organic solvent comprises toluene, xylene, methyl isobutyl ketone, methyl ethyl ketone, methyl propyl ketone, isopentyl methyl ketone or combination of.

13. The sensor device of claim 1 , wherein the organic solvent-soluble metal complex is selected from the group consisting of tris(triphenylphosphine) ruthenium (II) dichloride, (ethylecyclopentadienyl)-(triphenylphosphine)copper(I), triirondo-decacarbonyl, triruthenium dodecacarbonyl, and bromotris(triphenylphosphine)copper (I).

14. The sensor device of claim 1, wherein the conductive polymer is polyacetylene, polyaniline or polypyrrole.

15. The sensor device of claim 1, wherein the conductive polymer is polyaniline.

16. The sensor device of claim 1, wherein polyaniline is in protonated form.

17. The sensor device of claim 6, wherein the polymeric binder is selected from a polyurethane, a polyvinyl butyral, a polyacrylate, polyvinyl acetate, polystyrene, polystyrene acrylate, a polyurea, a polyimide, an amide, an epoxy, a glycidyl- Si-Zr-containing solgel, a polyester, a phenoxy resin, a polysulfide, polyolefins or mixtures thereof, thermally and photochemically curable acrylic polymers or copolymers.

18. The sensor device of claim 17, wherein the polyurethane is curable polyurethane.

19. The sensor device of claim 18, wherein curable polyurethane is 2-part curable polyurethane.

20. The sensor device of claim 1, wherein the electrical bridge comprises polyaniline, organic solvent-soluble transition metal complex and polyurethane.

21. The sensor device of claim 1, wherein the first electrode and second electrode are electrically coupled to the conductive polymer such that when the conductive polymer is in the first impedance state, a first resistance is measurable across the first electrode and second electrode, and when the conductive polymer is in the second impedance state a second resistance is measurable across the first electrode and second electrode, and wherein the first resistance is different than the second resistance.

22. The sensor device of claim 1, wherein the electrical bridge additionally exhibits a change in color.

23. A sterilization system, the sterilization system comprising: a sterilizer in a closed system configured to receive one or more medical devices for sterilization; and the sensor device according to claim 1 disposed in the sterilizer.

24. A method comprising: providing the sensor device according to claim 1, exposing the sensor device to a sterilant in a sterilization process.

25. The method according to claim 24, wherein the sterilant comprises hydrogen peroxide.

26. A sensor device comprising: a sterilant-responsive switch comprising: a first electrode and a second electrode, each having a first end electrically coupled to a circuit and a second end; a conductive polymer having a first state and a second state; and an organic solvent soluble metal complex; and a polymeric binder; wherein the conductive polymer is capable of being converted from being in the first state to being in the second state when in contact with a sterilant.

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