TECHNICAL FIELD

The present disclosure relates generally to diagnostic devices for measuring a solution characteristic of a sample; more specifically, to devices, systems, and methods for measuring a solution characteristic of a sample comprising microorganisms.

BACKGROUND

Infections caused by anti-infective resistant infectious agents or microbes are a significant problem for healthcare professionals in hospitals, nursing homes, and other healthcare environments. For example, such infections can lead to a potentially life-threatening complication known as sepsis where chemicals released into the bloodstream by an infectious agent can trigger a dangerous whole-body inflammatory response as well as a vasoactive response causing fever, low blood pressure, and possibly death. When faced with such an infection, a preferred course of action is for a clinician to use anti-infective compounds judiciously, preferably only those necessary to alleviate the infection.

However, what occurs most frequently today is that until the organism is identified and tested for drug sensitivity, broad spectrum anti-infectives, often multiple drugs, are given to the patient to ensure adequacy of treatment. This tends to result in multiple drug resistant infectious agents. Ideally, the sensitivity of the infectious agent would be detected soon after its presence is identified. In order to determine the susceptibility of such infectious agents to anti-infectives, samples comprising such infectious agents must be quantified, which requires such samples to be assayed for microbial growth or lack thereof.

Existing biosensors used to assay infectious agents in biological samples or other types of samples often include an active sensing component having an active electrode and a reference sensing component having a reference electrode immersed in a reference solution that is in ion exchange contact with the sample of interest. Traditionally, this is accomplished using an Ag/AgCl electrode in an aqueous reference buffer solution like KCl. However, this traditional sensor design is not ideal for various reasons. First, silver or silver chloride can diffuse into the sample and inhibit the growth of microorganisms in the sample, thus complicating any measurements done on the sample. Moreover, traditional reference solutions are often provided in a thin glass-walled disposable container, which is costly to manufacture, store, and transport. Furthermore, microbial diffusion through the salt bridge formed between the sample and the reference solution can contaminate the reference solution. In addition, traditional biosensors often required the reference electrode to be positioned on the silicon die surface, which used valuable wafer real estate and further increased the cost of such sensors.

As a result of the above limitations and restrictions, there is a need for improved devices, systems, and methods to quickly and effectively assay a sample comprising microorganisms for microbial growth or lack thereof. Such a solution should be cost-effective and address the shortcomings of traditional biosensors.

SUMMARY

Disclosed are apparatus, systems, and methods for measuring a solution characteristic (e.g., an ORP or pH) of a sample comprising microorganisms. In one embodiment, a sensor apparatus for measuring a solution characteristic of a sample is disclosed. The sensor apparatus can comprise a sample container comprising a sample chamber configured to receive the sample and a reference sensor component. The reference sensor component can comprise a reference conduit comprising a reference conduit cavity, a reference conduit first opening, and a reference conduit second opening. The reference sensor component can also comprise a wicking component extending through the reference conduit cavity having a wick distal end and a wick proximal end. At least part of the wicking component can be in fluid communication with the sample chamber such that at least some of the sample is drawn by the wicking component in a direction of the wick proximal end. The reference sensor component can also comprise a reference electrode material disposed at the wick proximal end.

The sensor apparatus can further comprise an active sensor component comprising an active electrode material. At least part of the active electrode material can extend into the sample chamber and be in fluid contact with the sample when the sample chamber is filled, at least partially, with the sample.

The reference sensor component and the active sensor component can be electrically coupled by conductive connections to a parameter analyzer. The solution characteristic of the sample can be determined based on a potential difference measured between the active electrode material and the reference electrode material.

The sensor apparatus can comprise a container cap configured to be removably coupled to the sample container. The reference conduit can extend from an underside of the container cap. The container cap can be made in part of a non-conducting material. The container cap can be made in part of a transparent non-conducting material such that at least part of the wicking component is visible through the container cap.

The sample container can be made in part of at least one of a ceramic material and a polymeric material. The reference electrode material can be an electrically-conductive ink applied or dispensed on the wick proximal end. The electrically-conductive ink applied or dispensed on the wick proximal end can be hardened by curing. In some embodiments, the electrically-conductive ink can be a silver-silver chloride ink.

The wicking component can be made in part of a porous polymeric material. In some embodiments, the wicking component can be made in part of high density polyethylene (HDPE). In other embodiments, the wicking component can be made in part of natural fibers. The wicking component can comprise pores sized between about 15 μm to about 150 μm.

The wicking component can be treated by a surfactant such that at least a surface of the wicking component can be covered by the surfactant. The surfactant can be configured to increase a hydrophilicity of the wicking component.

The sensor apparatus can further comprise an aeration port defined along at least one of a bottom side and a lateral side of the sample container. In some embodiments, a hydrophobic air-permeable membrane can cover the aeration port. The aeration port and the hydrophobic air-permeable membrane can be configured to allow air to enter the sample chamber through the aeration port and the hydrophobic air-permeable membrane to aerate the sample chamber.

When the reference sensor component is implemented as a container cap, the container cap can be configured to be removably coupled to the sample container via an attachment connection and an additional hydrophobic air-permeable membrane can cover at least part of an underside of the container cap. In these embodiments, an airflow pathway can be created when the container cap is screwed on to the sample container via the attachment connection (e.g., a threaded connection). The airflow pathway can include the aeration port, the hydrophobic air-permeable membrane, the sample chamber, the additional hydrophobic air-permeable membrane, and air gaps defined in between the container cap and the sample container along the attachment connection.

In some embodiments, the solution characteristic measured by the sensor apparatus is pH and the active electrode material of the active sensor component can be made in part of a pH-sensitive material. In some embodiments, the pH-sensitive material comprises at least one of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, and zirconium dioxide.

In other embodiments, the solution characteristic measured can be an oxidation reduction potential (ORP) of the sample and the active electrode material of the active sensor component can be made in part of a redox-sensitive material. The redox-sensitive material can comprise at least one of platinum, gold, silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, and zirconium dioxide. In these and other embodiments, the parameter analyzer can be or comprise at least part of a voltmeter and a multimeter.

Also disclosed is a reference sensor component. The reference sensor component can be configured to removably couple to a sample container configured to receive a sample. The reference sensor component can also comprise a reference conduit comprising a reference conduit cavity. In some embodiments, the reference sensor component can be implemented as a container cap. The reference conduit can extend from an underside of the container cap.

The reference sensor component can comprise a wicking component disposed within part of the reference conduit cavity having a wick distal end and a wick proximal end. At least part of the wicking component can be configured to be in fluid contact with the sample when the container cap is coupled to the sample container such that at least some of the sample is drawn by the wicking component in a direction of the wick proximal end. The reference sensor component can also comprise a reference electrode material disposed at the wick proximal end. The reference electrode material can be configured to exhibit a substantially stable electrode potential compared to an active electrode in electrical communication with the reference electrode material.

The reference sensor component can be made in part of a non-conducting material. When the reference sensor component is implemented as a container cap, the container cap can be made in part of a non-conducting material. In certain embodiments, the container cap can be made in part of a transparent non-conducting material such that at least part of the wicking component is visible through the container cap.

In some embodiments, the reference electrode material can be an electrically-conductive ink applied or dispensed on the wick proximal end. The electrically-conductive ink applied or dispensed on the wick proximal end can be hardened by curing. In some embodiments, the electrically-conductive ink can be a silver-silver chloride ink.

The wicking component can be made in part of a porous polymeric material. In other embodiments, the wicking component can be made in part of natural fibers. The wicking component can comprise pores sized between about 15 μm to about 150 μm.

The wicking component can be treated by a surfactant such that at least a surface of the wicking component is covered by the surfactant. The surfactant can be configured to increase a hydrophilicity of the wicking component.

Disclosed is also a method of measuring a solution characteristic of a sample. The method can comprise filling a sample chamber of a sample container with a sample comprising an infectious agent, attaching a reference sensor component (e.g., implemented as a container cap) to the sample container, electrically coupling a reference electrode material of the reference sensor component to a parameter analyzer and electrically coupling the parameter analyzer to an active sensor component comprising an active electrode material, and determining the solution characteristic of the sample based on a potential difference measured between the active electrode material and the reference electrode material.

At least part of the active electrode material can extend into the sample chamber and is in fluid contact with the sample. The reference sensor component can comprise a reference conduit comprising a reference conduit cavity, a reference conduit first opening, and a reference conduit second opening. The reference conduit cavity can be filled in part by a wicking component extending through the reference conduit cavity having a wick distal end and a wick proximal end.

At least part of the wicking component can be in fluid contact with the sample within the sample chamber. At least some of the sample can be drawn by the wicking component (e.g., by capillary action) in a direction of the wick proximal end.

The reference electrode material can be disposed at the wick proximal end. The reference electrode material can be an electrically-conductive ink applied or dispensed on the wick proximal end. The electrically-conductive ink can be hardened by curing. In some embodiments, the electrically-conductive ink can be a silver-silver chloride ink.

The method can further comprise pumping air into the sample chamber through an aeration port defined along at least one of a bottom side and a lateral side of the sample container and a hydrophobic air-permeable membrane covering the aeration port, wherein the air pumped into the sample chamber aerates the sample. The air pumped into the sample chamber can exit the sample chamber through an additional air-permeable membrane covering at least part of an underside of the container cap and through air gaps defined in between the container cap and the sample container along an attachment connection.

The step of determining the solution characteristic of the sample can comprise determining the pH of the sample. The active electrode material can be made in part of a pH-sensitive material. In some embodiments, the pH-sensitive material can comprise at least one of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, and zirconium dioxide.

In other embodiments, the step of determining the solution characteristic of the sample can comprise determining an oxidation reduction potential (ORP) of the sample and wherein the active electrode material is made in part of a redox-sensitive material. The redox-sensitive material can comprise at least one of platinum, gold, silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, and zirconium dioxide.

A method of manufacturing a reference sensor component is disclosed. The method can comprise providing a container cap configured to be removably coupled to a sample container configured to receive a sample. A reference conduit can extend from an underside of the container cap. The reference conduit can comprise a reference conduit cavity. The method can also comprise positioning a wicking component into the reference conduit cavity. The wicking component can comprise a wick distal end and a wick proximal end. The method can further comprise applying or dispensing an electrically-conductive ink on the wick proximal end and curing the electrically-conductive ink until the electrically-conductive ink hardens.

The method can further comprise applying or dispensing, on the wick proximal end, a volume of the electrically-conductive ink between about 50 μL and 500 μL. The electrically-conductive ink can be cured at a temperature above 100° C. The electrically-conductive ink can be cured for a period of time between about 60 minutes and about 180 minutes.

In some embodiments, the reference conduit can be tapered. The wicking component can be shaped such that the wicking component tapers from the wick proximal end to the wick distal end.

Disclosed herein is another embodiment of a sensor apparatus for measuring a pH of a sample. The sensor apparatus can comprise a sample container comprising a sample chamber configured to receive the sample and a reference sensor component.

The reference sensor component can comprise a reference conduit comprising a reference conduit cavity, a reference conduit first opening and a reference conduit second opening. In some embodiments, the reference conduit cavity can be at least partially filled with a reference buffer gel. A segment of the reference conduit can extend into the sample chamber. The reference conduit second opening can be configured to allow the sample to be in fluid contact with the reference buffer gel. A reference electrode can extend partially into the reference conduit cavity filled with the reference buffer gel.

The sensor apparatus can further comprise an active sensor component comprising an active electrode housing extending into the sample chamber and an active electrode housed partially within the active electrode housing. The active electrode can comprise a sample contact surface.

The active electrode can be disposed at a distal end of the active electrode housing. The active electrode housing can be configured to expose the sample contact surface such that the sample contact surface is in fluid communication with the sample.

A conductive contact layer can be coupled to the active electrode and positioned proximal to the active electrode within the active electrode housing. The conductive contact layer and the reference electrode can be electrically coupled by conductive connections to a voltmeter. The pH of the sample can be measured based on a potential difference between the active electrode and the reference electrode.

The reference conduit can comprise conduit walls. The conduit walls can taper from a reference conduit proximal end to a reference conduit distal end such that a first opening area of the reference conduit first opening is larger than a second opening area of the reference conduit second opening.

The reference electrode can comprise a reference electrode tip. The reference electrode tip can be positioned proximal to the reference conduit second opening when the reference electrode is partially extended into the reference conduit cavity such that a volume of reference buffer gel separates the reference electrode tip from the reference conduit second opening. The reference conduit cavity can be filled with about 100 μL to about 500 μL of reference buffer gel.

The reference electrode can be made in part of one or more metals. In some embodiments, the reference electrode can be made in part of platinum, stainless steel, or a combination thereof.

The active electrode can be made in part of a metal oxide. In some embodiments, the active electrode can be made in part of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, zirconium dioxide, or a combination thereof.

The conductive contact layer can be made in part of one or more metals. The conductive contact layer can be made in part of aluminum, copper, platinum, or a combination thereof.

In some embodiments, the reference buffer gel can be an agar gel formed from agar powder and a reference buffer solution. The agar powder in the agar gel can be at a concentration of about 1% (w/v %) to about 5% (w/v %).

The reference buffer solution can comprise potassium hexacyanoferrate(III), potassium hexacyanoferrate(II), potassium dihydrogen phosphate, disodium hydrogen phosphate, or a combination thereof. In other embodiments, the reference buffer solution can comprise potassium chloride.

The sensor apparatus can comprise an aeration conduit. A segment of the aeration conduit can extend into the sample chamber. The aeration conduit can be configured to aerate the sample within the sample container.

Also disclosed is another embodiment of a sensor apparatus for measuring an oxidation-reduction potential (ORP) of a sample. The sensor apparatus can comprise a sample container comprising a sample chamber configured to receive the sample and a reference sensor component.

The reference sensor component can comprise a reference conduit comprising a reference conduit cavity, a reference conduit first opening and a reference conduit second opening. The reference conduit cavity can be at least partially filled with a reference buffer gel. A segment of the reference conduit can extend into the sample chamber.

The reference conduit second opening can be configured to allow the sample to be in fluid contact with the reference buffer gel. A reference electrode can extend partially into the reference conduit cavity filled with the reference buffer gel.

The sensor apparatus can further comprise an active sensor component. The active sensor component can comprise an active electrode housing extending into the sample chamber and an active electrode housed partially within the active electrode housing. The active electrode can comprise a sample contact surface. The active electrode can be disposed at a distal end of the active electrode housing and the active electrode housing can be configured to expose the sample contact surface such that the sample contact surface is in fluid communication with the sample. The active electrode and the reference electrode can be electrically coupled by conductive connections to a voltmeter. The ORP of the sample can be measured based on a potential difference between the active electrode and the reference electrode.

The reference conduit can comprise conduit walls. The conduit walls can taper from a reference conduit proximal end to a reference conduit distal end such that a first opening area of the reference conduit first opening is larger than a second opening area of the reference conduit second opening. The reference conduit cavity can be filled with about 100 μL to about 500 μL of reference buffer gel.

The reference electrode can comprise a reference electrode tip. The reference electrode tip can be positioned proximal to the reference conduit second opening when the reference electrode is partially extended into the reference conduit cavity such that a volume of reference buffer gel separates the reference electrode tip from the reference conduit second opening.

The reference electrode can be made in part of one or more metals. In some embodiments, the reference electrode can be made in part of platinum, stainless steel, or a combination thereof.

The active electrode can be made in part of one or more metals, one or more metal oxides, or a combination thereof. For example, the active electrode can be made in part of platinum, gold, silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, zirconium dioxide, or a combination thereof.

The reference buffer gel can be an agar gel formed from agar powder and a reference buffer solution. The agar powder in the agar gel can be at a concentration of about 1% (w/v %) to about 5% (w/v %).

The reference buffer solution can comprise potassium hexacyanoferrate(III), potassium hexacyanoferrate(II), potassium dihydrogen phosphate, disodium hydrogen phosphate, or a combination thereof. In other embodiments, the reference buffer solution can comprise potassium chloride.

The sensor apparatus can further comprise an aeration conduit or aeration port. A segment of the aeration conduit can extend into the sample chamber. The aeration conduit can be configured to aerate the sample within the sample container.

Also disclosed is another embodiment of a sensor apparatus for measuring a pH of a sample. The sensor apparatus comprising a sample container comprising a sample chamber configured to receive the sample and a reference sensor component.

The reference sensor component can comprise a reference conduit comprising a reference conduit proximal end defining a reference conduit first opening, a reference conduit distal end defining a reference conduit second opening, and a reference conduit cavity in between the reference conduit proximal end and the reference conduit distal end.

The reference conduit cavity can be at least partially filled with a reference buffer solution. A segment of the reference conduit can extend into the sample chamber. A reference electrode can extend partially into the reference conduit cavity filled with the reference buffer solution.

An ion exchange membrane can be coupled to the reference conduit distal end and configured to obstruct the reference conduit second opening. The ion exchange membrane can be configured to prevent the sample from intermixing with the reference buffer solution but allow ions to transverse the ion exchange membrane.

The sensor apparatus can further comprise an active sensor component. The active sensor component can comprise an active electrode housing extending into the sample chamber and an active electrode housed partially within the active electrode housing.

The active electrode can comprise a sample contact surface. The active electrode can be disposed at a distal end of the active electrode housing and the active electrode housing can be configured to expose the sample contact surface such that the sample contact surface is in fluid communication with the sample.

A conductive contact layer can be coupled to the active electrode and positioned proximal to the active electrode within the active electrode housing. The conductive contact layer and the reference electrode can be electrically coupled by conductive connections to a voltmeter and wherein the pH of the sample is measured based on a potential difference between the active electrode and the reference electrode.

The reference conduit can comprise conduit walls. The conduit walls can taper from a reference conduit proximal end to a reference conduit distal end such that a first opening area of the reference conduit first opening is larger than a second opening area of the reference conduit second opening. The reference conduit cavity can be filled with about 100 μL to about 500 μL of reference buffer solution.

The reference electrode can comprise a reference electrode tip. The reference electrode tip can be positioned proximal to the ion exchange membrane when the reference electrode is partially extended into the reference conduit cavity such that a volume of reference buffer solution separates the reference electrode tip from the ion exchange membrane.

In some embodiments, the ion exchange membrane can be a perfluoro-sulfonated ionomer membrane. For example, the perfluoro-sulfonated ionomer membrane can be a Nafion® membrane. The ion exchange membrane can have a thickness of about 25 μm to about 180 μm.

The reference electrode can be made in part of one or more metals. For example, the reference electrode is made in part of platinum, stainless steel, or a combination thereof.

The active electrode can be made in part of a metal oxide. For example, the active electrode can be made in part of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, zirconium dioxide, or a combination thereof.

The conductive contact layer can be made in part of one or more metals. In some embodiments, the conductive contact layer can be made in part of aluminum, copper, platinum, or a combination thereof.

The reference buffer solution can comprise potassium hexacyanoferrate(III), potassium hexacyanoferrate(II), potassium dihydrogen phosphate, disodium hydrogen phosphate, or a combination thereof. In other embodiments, the reference buffer solution can comprise potassium chloride.

The sensor apparatus can further comprise an aeration conduit. A segment of the aeration conduit extends into the sample chamber, and wherein the aeration conduit is configured to aerate the sample within the sample container.

The reference sensor component can be removably coupled to the sample container such that the reference sensor component is detachable from the sample container.

Disclosed herein is another embodiment of a sensor apparatus for measuring an oxidation-reduction potential (ORP) of a sample. The sensor apparatus comprising a sample container comprising a sample chamber configured to receive the sample and a reference sensor component.

The reference sensor component can comprise a reference conduit comprising a reference conduit proximal end defining a reference conduit first opening, a reference conduit distal end defining a reference conduit second opening, and a reference conduit cavity in between the reference conduit proximal end and the reference conduit distal end. The reference conduit cavity can be at least partially filled with a reference buffer solution. A segment of the reference conduit can extend into the sample chamber. The sensor apparatus can further comprise a reference electrode extending partially into the reference conduit cavity filled with the reference buffer solution.

An ion exchange membrane can be coupled to the reference conduit distal end and configured to obstruct the reference conduit second opening. The ion exchange membrane can be configured to prevent the sample from intermixing with the reference buffer solution but allow ions to transverse the ion exchange membrane.

Moreover, the sensor apparatus can comprise an active sensor component. The active sensor component can comprise an active electrode housing extending into the sample chamber and an active electrode housed partially within the active electrode housing.

The active electrode can comprise a sample contact surface. The active electrode can be disposed at a distal end of the active electrode housing and the active electrode housing is configured to expose the sample contact surface such that the sample contact surface is in fluid communication with the sample.

The active electrode and the reference electrode can be electrically coupled by conductive connections to a voltmeter. The ORP of the sample can be measured based on a potential difference between the active electrode and the reference electrode.

The reference conduit can comprise conduit walls. In some embodiments, the conduit walls can taper from a reference conduit proximal end to a reference conduit distal end such that a first opening area of the reference conduit first opening is larger than a second opening area of the reference conduit second opening. The reference conduit cavity can be filled with about 100 μL to about 500 μL of reference buffer solution.

The reference electrode can comprise a reference electrode tip. The reference electrode tip can be positioned proximal to the ion exchange membrane when the reference electrode is partially extended into the reference conduit cavity such that a volume of reference buffer solution separates the reference electrode tip from the ion exchange membrane.

The reference electrode can be made in part of one or more metals. For example, the reference electrode can be made in part of platinum, stainless steel, or a combination thereof.

The active electrode can be made in part of one or more metals, one or more metal oxides, or a combination thereof. For example, the active electrode can be made in part of platinum, gold, silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium dioxide, iridium dioxide, ruthenium dioxide, zirconium dioxide, or a combination thereof.

In some embodiments, the reference buffer solution can comprise potassium hexacyanoferrate(III), potassium hexacyanoferrate(II), potassium dihydrogen phosphate, disodium hydrogen phosphate, or a combination thereof. In other embodiments, the reference buffer solution can comprise potassium chloride.

As previously discussed, an ion exchange membrane can be coupled to the reference conduit distal end and configured to obstruct the reference conduit second opening. In some embodiments, the ion exchange membrane can be a perfluoro-sulfonated ionomer membrane. For example, the perfluoro-sulfonated ionomer membrane can be a Nation® membrane. The ion exchange membrane can have a thickness of about 25 μm to about 180 μm.

The sensor apparatus can further comprise an aeration conduit. A segment of the aeration conduit can extend into the sample chamber. The aeration conduit can be configured to aerate the sample within the sample container.

The reference sensor component can be removably coupled to the sample container such that the reference sensor component is detachable from the sample container.

