Patent ID: 12188922

DETAILED DESCRIPTION

Disclosed herein is an overhead sensor assembly10for determining partial pressures of gases, concentrations of electrolytes and metabolites in a fluid sample. Fluids, such as whole blood, can be analyzed for many analytes, including the electrolytes potassium (K+), sodium (Na+), and calcium (Ca2+) and metabolites such as glucose, lactate, blood urea nitrogen (BUN), and creatine. The sensors used for these measurements are ion-specific or ion-selective electrodes.

The sensor assembly10is a component that is utilized within a cartridge that is wholly replaceable after a set number of fluid analyses have taken place or after the passage of a set amount of time. Disclosed herein is a subcomponent assembly that is central to the analysis of the fluid, and most importantly, is configured to minimize the volume of fluid, such as whole blood, that is required for analysis. Minimizing the volume of blood required for analysis is central to the inventive concept disclosed herein.

As seen inFIG.1, a sensor assembly10for analysis of physical parameters and chemical constituents of small volume samples of bodily fluids is disclosed. The assembly10comprises a sensor panel14with an upper surface16and a lower surface18and at least one analyte sensor20located on the lower surface18. The sensor panel14is preferably fabricated on a ceramic substrate: however, an engineered plastic substrate would function equally as well. In a preferred embodiment, the sensor assembly10utilizes an adhesive layer24with an upper surface26and a lower surface28. The adhesive layer24utilizes first and second longitudinal edges30,32and a contoured fluid pathway cutout36spanning proximate the first and second longitudinal edges30,32. The upper surface16of the adhesive layer24is adhesively secured to the lower surface18of the sensor panel14. The lower surface28of the adhesive layer24is secured to an inset bed41of the sensor cartridge base40. This disclosure contemplates that the adhesive layer24is optional and functionality of the sensor assembly10is not adversely impacted by elimination of the adhesive layer24.

FIG.1reveals the sensor cartridge base40with a fluid inlet42and a fluid outlet44and a contoured fluid pathway48extending between the inlet42and the outlet44. A set of coordinates revealing the X, Y and Z directions are also shown inFIG.1and serve to provide a basis for identifying orientation of a feature or claim element throughout this disclosure. The contoured fluid pathway48mirrors the shape and span of the contoured fluid pathway cutout36of the optional adhesive layer24. A fluid sample50is input at the fluid inlet42and traverses along the fluid pathway48for contact with the at least one analyte sensor20before exiting at the fluid outlet44.

The volumetric capacity of the contoured fluid pathway48between the fluid inlet42and the fluid outlet44is preferably in the range of from about 20 to 35 μl which is a de minimis amount. The need for a very small volume of fluid, as previously detailed, is central to this disclosure as blood draws from neonates, in particular, have been a significant driver for smaller blood volume analytical technologies.

The sensor assembly10, in a preferred embodiment, utilizes a sensor panel14with at least two analyte sensors20located on the lower surface18. Accompanying each analyte sensors20are at least two analyte sensor contacts54. The sensor panel analyte contacts54are preferably located on the upper surface16of the sensor panel14and are laterally and oppositely disposed from one another across the contoured fluid pathway48. Alternatively, the sensor contacts54may be located on the lower surface18of the sensor panel as is indicated inFIG.1.

The sensor contacts54will be engaged by prepositioned leads (not shown) within the sensor cartridge assembly (not shown). A critical feature of the disclosed assembly is that dimensions of the contoured fluid pathway48increases, in one or both of the Y and Z directions, in close proximity to an analyte sensor20and reduces, in one or both of the Y and Z directions, when transitioning between analyte sensors. An exemplary transition area55, between analyte sensors, can be seen inFIGS.4,5A and5B. This narrowed transition area55between sensors20facilitates the reduced need for fluid volume in order to perform the desired analysis of the fluid. In an embodiment, the dimensions of the contoured fluid pathway48increases in the Y direction, in close proximity to an analyte sensor20and reduces in Y direction, when transitioning between analyte sensors while the dimension in the Z axis remains constant throughout the flow path. In a variation of this embodiment, the dimensions of the contoured flow path in the Z axis may also increase and decease along with the dimensions in the Y axis. In yet another illustrative embodiment, the dimensions of the contoured fluid pathway48increases in the Z direction, in close proximity to an analyte sensor20and reduces in Z direction, when transitioning between analyte sensors while the dimension in the Y axis remains constant throughout the flow path. In a variation of this embodiment, the dimensions of the contoured flow path in the Y axis may also increase and decease along with the dimensions in the Z axis.

FIG.2reveals an exemplary sectional view ofFIG.1at sectional line2-2. The sectional view atFIG.2reveals a rounded fluid flow path48. Alternative configurations of the fluid flow path48are also contemplated by this disclosure. For example, a square, rectangular or, hexagonally shaped fluid flow path, among others, are also fully contemplated. The contoured fluid pathway48is comprised of a first upper edge60and a second upper edge62. These edges60,62are at the intersection of the walls of the fluid flow pathway48and the inset bed41of the cartridge base40. The widest span between the first edge60) and the second edge62is preferably in the range of about 0.300 to 0.600 mm; however, dimensions outside of this range are also contemplated by this disclosure.

FIG.3reveals a view ofFIG.1at sectional line3-3, at a point where the contoured fluid pathway narrows substantially such as the area seen at reference number55inFIG.4. The contoured fluid pathway48in this instance is comprised of a first upper edge64and a second upper edge66. These edges64,66are at the intersection of the walls of the fluid flow pathway48and the inset bed41of the cartridge base40. This narrowest span between the first upper edge64and the second upper edge66is in the range of 0.100 mm to 0.250 mm and the depth of the contoured fluid pathway48from the narrowest cross section to the widest cross section is in the range of from 0.200 to 0.400 mm.

The contoured fluid pathway48oscillates between a wider and narrower55span along the entire length of the pathway in order to minimize the amount of fluid required to pass beneath the analyte sensors20and yet maintain a sufficiently unrestricted fluidic connection in order to sustain fluid pressure to facilitate conveyance through the sensor assembly10.

Though the term “beneath” may be used in describing the orientation of the fluid flow path48relative to the sensor location, this disclosure contemplates that the fluid flow path48may also be located above the analyte sensors20and the term “beneath” should not be considered limiting in that respect. The fluid path widens when in proximity to a sensor because a certain minimum surface area of the analyte sensor20must contact the fluid in order to take a reading. Where there are no sensors in the fluid path, there are no such surface area requirements and the fluid path narrows.

As seen inFIG.4the sensor assembly10is capable of analyzing a wide range of constituent concentrations and fluid parameters. The sensor assembly10disclosed herein includes analyte sensors20capable of measuring, for example, pCO2, O2, BUN, Na, Cre, K, Ca, Lac, Mg, Glu, Cl and pH. Though the sensors20are identified in a particular order inFIG.4, this disclosure contemplates that the sensors may be ordered in many different configurations without impacting the functionality of the fluid analyzer.

The above listed parameters are measured by many blood analyzers.FIG.5Areveals a perspective view of how the fluid would appear as it traverses, in the X direction, through the contoured fluid pathway48of the sensor cartridge base40. As previously discussed, the fluid pathway increases in the Y and Z directions, growing larger in both dimensions, when in proximity to the analyte sensors20and lessens, decreasing in dimension in the Y and Z directions, when traversing between the sensors20thereby minimizing the sample volume necessary to perform the analysis.FIG.5Breveals a view from beneath the fluid path providing additional detail on the narrowing and widening profile of the fluid pathway48. Where there are no sensors in the fluid path, there are no sensor surface area requirements thereby allowing the fluid path to lessen dimensionally as detailed immediately above.

In operation, the fluid, typically blood, is withdrawn from a patient generally via a syringe or other standard blood draw technique. As previously detailed, the blood draw is very minimal in volume, generally no greater than 30 μl. The fluid50is then aspirated into the fluid inlet port42. Upon entering the fluid inlet port42, the fluid50traverses along the contoured fluid pathway48. This traverse along the fluid pathway48places the fluid beneath one, and preferably a multitude of analyte sensors20, capable of detecting either a change in voltage or amperage.

The diverging and converging of the fluid pathway minimizes the overall volume of fluid required for proper operation of the sensor assembly10. The change in voltage or amperage at the analyte sensors (ion-selective electrodes) is relayed to the analyte sensor contacts54mounted to the sensor panel14. The change in voltage, or amperage, detected at the analyte sensors20is then transmitted from the sensor contacts54to the analyzer (not shown). The analyzer, based upon a proprietary algorithm determines the concentrations of the fluid (blood) constituents and other parameters such as blood gases.

Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of the disclosed technology. Embodiments of the disclosed technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from its scope. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the disclosed technology.

It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.