Patent Description:
Description of Related Art. Among various diagnostic tests, Enzyme-linked immunosorbent assay (ELISA) has been demonstrated to provide compelling and high performance quantitative and qualitative results. However, the current ELISA systems are generally ill-suited to deploy at point-of-care testing and other field applications due to such common drawbacks as: long testing time (<NUM>-<NUM> hours + overnight coating); large sample and reagent consumption (<NUM>-<NUM>µL per sensor well); and the requirement of bulky and expensive microplate readers. In order to achieve point of care viability, numerous performance advances are needed within the same ELISA detection scheme. In particular, improvements are needed to make an ELISA detection scheme rapid, affordable, portable and complete. Furthermore, an ELISA system well-suited to point-of-care applications needs to be compact enough for use in limited spaces, in emergency critical care sectors, as well as research and development laboratories and field applications.

Some prior art systems, such as that proposed in <CIT> of Palo Alto, CA, recognize the need for point-of-care diagnostic systems, but have failed to adequately optimize optical detection efficiency and continue to advocate bulky well plate designs. Further known prior art includes: <NPL>; <NPL>; <NPL>; <CIT>; <CIT>; and <CIT>.

There is therefore a need in the art for an improved diagnostic system, and components therefor, which will enable ELISA detection schemes that are rapid, affordable, portable, complete and that can be implemented in compact configurations suitable for limited spaces and field applications.

According to a first aspect of this invention, a sensor unit for an optofluidic diagnostic system is configured configured for sequential movement into and out of registry with a plurality of discrete wells along a vertical path, said sensor unit comprises a top end, a bottom end spaced vertically from said top end, a single fluid duct extending continuously from said top end to said bottom end and a reactor section adjacent said bottom end. The fluid duct includes a reactive coating agent immobilized over at least a portion thereof in said reactor section. The reactor section has an outer geometric shape comprised of a plurality of exterior faces surrounding said fluid duct, one of said exterior faces comprises a planar observation face, at least a portion of said planar observation face is fabricated from an optically transmissive material. The fluid duct is generally cylindrical whereby the portion of said reactor section between said duct and said observation face comprises a generally plano-concave lens, and said outer geometric shape of said reactor section is centered about said fluid duct. The reactor section has a leading tip formed directly adjacent said bottom end of said duct and said leading tip has a square-to-round lofted blend transition.

The flat, or planar, observation face enables improved imaging conditions by establishing a more uniform, more evenly distributed optical color representation of the biochemical molecules resolved during the diagnostic procedure. A flat observation face advantageously spreads color-affected light, thus increasing the efficiency, sensitivity and effectiveness of optical detection. The unique configuration of the optofluidic sensor units thus improves analyte capture efficiency, can reduce assay time which can lead to a more rapid diagnosis, and ultimately facilitates high-throughput screening.

According to a second aspect of this invention, a combination of the sensor unit with a multi-well test plate for an optofluidic diagnostic system is configured to interact with at least one sensor unit moved sequentially into and out of registry therewith. The test plate comprises a plurality of wells. Each well has a well depth defined by an upper mouth and a lower base. Each well in the test plate has a generally equal well depth. At least three wells are arranged in a sequence cluster. At least one well in the sequence cluster comprises a sample reservoir dedicated to the containment of a liquid reagent. At least one well in the sequence cluster comprises a drainage chamber dedicated to the drainage of liquid reagents from a sensor unit. And at least one well in the sequence cluster comprises a colorant reservoir dedicated to the containment of a liquid color development reagent. The base of each well has a concave square-to-round shape.

The test plate of this invention is less bulky by comparison to standard prior art well plates. The test plate can avoid the requirement to add reagents manually. The test plate is beneficial in improving analyte capture efficiency and allows for addition and withdrawal of analytes (solution) by either capillary force or induced pressure differential or a combination of both. The test plate is conducive to use of predefined and prepopulated reagents in the wells and provides efficient means for reagents/analytes delivery and draining. Furthermore, the test plate cooperates with an overall system that can be deployed at bedside of patients, doctors' offices, and in space-limited laboratories.

It is further referred to an optical detection cartridge for an optofluidic diagnostic system. The optical detection cartridge comprises a plurality of isolation booths. Each isolation booth has a booth height defined by an open ceiling and a closed floor. Each isolation booth has an open viewport and optically-opaque sides. Each isolation booth is adapted to receive therein the reactor section of a sensor unit.

The optical detection cartridge makes optical cross-talk preventable among individual optofluidic sensor units, thus enabling improved accuracy in chemiluminescence or fluorescence detection schemes if desired. A optical detection cartridge is effective to increase the efficiency, sensitivity and effectiveness of optical detection, and directly facilitates high-throughput testing procedures.

These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein:.

Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, an optofluidic diagnostic system according to one exemplary embodiment of the invention is generally shown at <NUM> in <FIG>. The automated optofluidic diagnostic system <NUM> is designed for rapid biological and chemical analysis. Its many advantages include using less analyte and reagent solutions than the amount used in traditional protocol. Furthermore, the system <NUM> is able to perform high-throughput detections because of its capability to automatically load and unload the solutions.

Generally stated, the optofluidic diagnostic system <NUM> is composed of three primary parts or modules: a sensor array <NUM>, a test plate <NUM> and an optical detection cartridge <NUM>. Each module is independent of the other two modules, in the sense that each module is capable of stand-alone use independent of the unique attributes found in the other modules. However, all three of these modules find their greatest fulfillment when used in the combination which comprises the optofluidic diagnostic system <NUM>.

The sensor array <NUM> comprises a plurality of sensor units <NUM> arranged in formation. A single sensor unit <NUM> is shown in <FIG>. The invention may be practiced using only a single sensor unit <NUM>, as in <FIG>, however greater efficiencies can be gained by multiplying the number of sensor units <NUM> into a monolithic array <NUM> like that shown in <FIG> so that multiple diagnostic tests can be conducted concurrently. The array <NUM> of <FIG> depicts an exemplary arrangement in which twenty-four sensor units <NUM> are joined in a formation of two columns, each column containing twelve sensor units <NUM>. In an array <NUM> configuration, the distance between the center of one sensor unit <NUM> to the center of the next adjacent sensor unit <NUM> can be <NUM> to <NUM> (<NUM> to <NUM> inches) inches or even greater.

From the vantage of <FIG>, one of the columns of sensor units <NUM> can be described as the first or left-hand column and the other a second or right-hand column. In use, the first column trails the second column as the sensor array <NUM> is moved in hopping-like fashion through the sequential steps of a diagnostic test. That is, the second column is always a leading column. Although the array <NUM> is shown in several Figures as a 2x12 matrix, the actual number of sensor units <NUM> in an array <NUM> can be any desired number. Indeed, an array <NUM> may consist of only one column of any plural number of sensor units <NUM>. Or in some cases, it might be desirable to construct a sensor array <NUM> having more three or more columns of sensor units <NUM>. And to reiterate, a single sensor unit <NUM> operating solo can also be used to accomplish the methods of this invention without joining to other sensor units <NUM> into an array <NUM>. Many configurations of one or more sensor units <NUM> are possible.

Each sensor unit <NUM> can be seen to extend between a top end <NUM> and a bottom end <NUM>. The sensor units <NUM> are normally oriented in an upright posture so that its bottom end <NUM> is spaced vertically from its top end <NUM>. Each sensor unit <NUM> has a dedicated fluid duct <NUM> that extends continuously therethrough from its top end <NUM> to its bottom end <NUM>. The full length of the fluid duct <NUM> can be seen in the images of <FIG>. The fluid duct is generally cylindrical. In examples not falling under the scope of the invention, the fluid duct <NUM> is tapered and/or non-circular in cross-section. The fluid duct <NUM> has a continuous cross-sectional area that is generally cylindrical, i.e., it has a constant circular cross-section along its entire length. In some contemplated embodiments of this invention, the internal diameter of the fluid duct <NUM> is between about <NUM> and <NUM>(<NUM> and <NUM> inches). However, measurements outside this range are certainly possible. In fact, all dimensions and dimensional ranges provided throughout this description are mentioned for illustrative purposes only and are not to be construed as limiting the scope of the invention.

Returning to <FIG> and <FIG>, it can be seen that each sensor unit <NUM> includes a reactor section <NUM> adjacent its bottom end <NUM>. In the illustrated examples, the reactor section <NUM> comprises the lower half (approximately) of the sensor unit <NUM>. The upper half (approximately) of the sensor unit <NUM> comprises a coupler section <NUM>. A frame <NUM> is disposed between each reactor section <NUM> and its associated coupler section <NUM>. The frame <NUM> can serve as a mounting platform or feature in the case of a sensor unit <NUM> operating solo (<FIG>). The frames <NUM> can also be a convenient point of attachment for integrally joining one sensor unit <NUM> to the next adjacent sensor unit <NUM> when forming a monolithic array <NUM> as in the example of <FIG>.

The fluid duct <NUM> may include a reactive coating agent A that has been applied, i.e., immobilized, over at least a portion thereof within the reactor section <NUM>. The reactive coating agent A can be any suitable diagnostic substance, including but not limited to, assays used to assess the presence, amount or functional activity of a target entity (i.e., the analyte). The reactive coating agent A contemplated for use in this invention specifically includes, but is not limited to, solid-phase enzyme immunoassays such as those used in typical ELISA test procedures. The reactive coating agent A may either be applied by a manufacturer, by an intermediate vendor, or by the end-user as a preparatory step prior to actual use in the system <NUM>. It is also contemplated that the reactive coating agent A could be immobilized inside the fluid duct <NUM> using the system <NUM> of this invention but prior to the start of an actual diagnostic test.

The reactor section <NUM> may be partially or entirely fabricated from an optically transmissive material, including materials that can be characterized as fully transparent, semitransparent and/or translucent. More specifically, an optically transmissive material will be selected that has an index of refraction that closely approximates that of water or some other analyte liquid. By matching (or at least approximating) the index of refraction of the reactor section <NUM> with the refractive index of the liquid analyte to be used, light will pass from one to the other with minimal reflection or refraction losses. Two of the many suitable materials include glasses and plastics. The sensor units <NUM> can be manufactured by injection molding when a transparent plastic material (e.g., clear transparent polystyrene) is chosen.

The reactor section <NUM> has at least one planar observation face <NUM>, at least a portion of which is fabricated from the optically transmissive material. That is to say, at the very least, the portion of the reactor section <NUM> that compromises the observation face <NUM> must have some optically-transmissive properties. In the illustrated examples, the entire reactor section including the observation face <NUM> is made from an optically-transmissive material. When the sensor unit <NUM> is ganged with other sensor units <NUM> into an array <NUM>, the observation face <NUM> will face outwardly, i.e., in a direction away from all of the other sensor units <NUM> in the array <NUM>. The reactor section <NUM> has a predetermined outer geometric shape that is preferably, but not necessarily, generally centered about the fluid duct <NUM>. Contemplated geometric shapes include rectangles, triangles, hexagons and D-shapes to name a few. In the illustrated examples, the predetermined outer geometric shape of the reactor section <NUM> is generally square. The square shape produces four distinct flat exterior faces, one of which is the aforementioned observation face <NUM>. In cases such as this where a sensor array <NUM> is composed of reactor sections <NUM> having more than one planar exterior face, the observation face <NUM> will be distinguished as the one facing away from the other sensor units <NUM>, as shown in <FIG>.

Preferably, but perhaps not necessarily, the observation face <NUM> is oriented vertically, and thus generally parallel to the fluid duct <NUM>. In this manner, the cross-sectional thickness of optically transmissive material remains generally consistent along the length of the reactor section. In cases where the fluid duct <NUM> has a circular cross-section and extends parallel to the observation face <NUM>, this configuration produces a generally plano-concave lens as shown by the cross-sections in <FIG> and <FIG>. A plano-concave lens will have beneficial divergent light-handling properties in cases where the refraction indexes between the material of the reactor section <NUM> and analyte solutions contained within the fluid duct <NUM> do not match.

The reactor section <NUM> has a leading tip <NUM> formed directly adjacent the bottom end <NUM> of the fluid duct <NUM>. In the examples of <FIG> and <FIG>, the leading tip <NUM> is formed with a lofting square-to-round converging bended surface. In the example of <FIG>, the leading tip <NUM> is formed as a flat truncated surface. Other shapes are contemplated, including but not limited to semi-spherical. Some specific advantages are attained when the leading tip <NUM> is formed with a square to circle tapered lofted blend tip, as explained below in connection with <FIG>.

The coupler section <NUM> of each sensor unit <NUM> is designed to connect with a supply of - positive or/and negative generator. The medium is described at various points below as being air, but other gasses and fluids could be used instead. In the highly-simplified example of <FIG>, individual feed tubes <NUM> are connected to the coupler sections <NUM> in a sensor array <NUM> configuration. Instead of the individual tubes <NUM>, a manifold could be used to connect to the coupler sections <NUM>. Or perhaps the atmosphere above the entire sensor array <NUM> could be controlled to cause pressure/vacuum fluctuations at the bottom ends <NUM> of the fluid ducts <NUM>. For convenient connection to individual feed tubes <NUM> or a manifold (not shown), the coupler sections <NUM> may comprises a conically-tapered exterior surface that is centered about the fluid duct <NUM> to accomplish a friction fit. Of course, may other shapes and connection strategies may be used for the coupler section <NUM> to effectively connect with a supply of pressurized (positive and/or negative) air or other suitable fluid medium.

Each sensor unit <NUM> can thus be viewed as an open-ended tubular (i.e., hollow) structure whose fluid duct <NUM> is used as an inlet and outlet for reagents/analytes at a bottom end <NUM> thereof. Pressure differentials, if necessary, are introduced to the fluid duct <NUM> via its top end <NUM>. The reactor and coupler sections <NUM>, <NUM> are connected internally and smoothly via the internal fluid duct <NUM>. The preferred outer shape of the tubular reactor section <NUM> is square, and the preferred outer shape of the coupler section <NUM> is tapered (frusto-conical) for easy insertion of connecting tubes <NUM> that link to the pressure differential device(s). Although these shapes can, of course, be modified to suit different applications and manufacturability. That is to say, other geometric shapes may be considered, including but not limited to oval, elliptical, triangular, hexagonal and octagonal tubular configurations to name but a few of the many possible forms.

In the context of this optofluidic diagnostic system <NUM>, each sensor unit <NUM> is configured for sequential movement into and out of registry with a plurality of discrete wells <NUM> in the test plate <NUM>. In this manner, it can be said that the test plate <NUM> is adapted to receive the sensor array <NUM> in mating registry, as indicated by <FIG>. However, unlike the wells of a traditional multi-well microplate (e.g., a Microtiter™ plate), it is not intended that any chemical reactions take place in any of the wells <NUM> of the test plate <NUM>. Rather, in this present system, all chemical reactions of relevance will take place inside the rector sections <NUM> of the sensor units <NUM>. Thus, the wells <NUM> may be seen more as holders or storage centers for various elements used in the process of conducting biological and/or chemical analysis inside the reactor sections <NUM>.

Each well <NUM> is formed as a discrete comb-like cavity having a mouth <NUM> at its upper end and a closed base <NUM> at its lower end. The vertical distance between mouth <NUM> and base <NUM> is a well depth. In the illustrated examples, each well <NUM> in the test plate <NUM> has a generally equal well depth. However, since not all wells <NUM> have the same function or job, it is conceivable that the wells <NUM> could have different depths and/or different configurations for the base <NUM>. The wells <NUM> each have a predetermined inner geometric shape that generally corresponds to the predetermined outer geometric shape of the reactor sections <NUM>. In other words, if the outer cross-section of the reactor section <NUM> is square, then the inner cross-section of the well <NUM> is also square. This is perhaps best shown in <FIG> where a cross-section is taken through a well <NUM> with a reactor section <NUM> poised therein. Preferably a generous sliding fit clearance is maintained between the OD of the reactor sections <NUM> and the ID of the wells <NUM> so that the reactor sections <NUM> can be easily inserted into and withdrawn from the wells <NUM> along a vertical path during the several steps in a diagnostic process.

The test plate <NUM> in <FIG> is shown in the exemplary form having twelve rows corresponding to the number of rows of the sensor array <NUM>. In this illustration, each row has a trajectory extending toward the lower right-hand corner of the image, whereas each column has a trajectory extending toward the lower left-hand corner of the image. In an X-Y coordinate system as viewed from above (e.g., <FIG>), the rows may be said to extend in a horizontal X-direction and the columns in a vertical Y-direction. In most contemplated embodiments, the test plate <NUM> will have at least as many rows as the sensor array <NUM>. The test plate <NUM> could easily have more rows than the sensor array <NUM>, however it is unlikely that the test plate <NUM> will have fewer rows than the sensor array. The test plate <NUM> in <FIG> is shown in the exemplary form having twenty-four columns corresponding (or proportionally-corresponding) to the discrete steps needed to accomplish a diagnostic test. In this example, twelve discrete steps are possible. This is because the sensor array <NUM> shown here has two columns of sensor units <NUM>. Thus, the twenty-four columns of the test plate <NUM> must be shared by the two columns of sensor units <NUM>. (<NUM>÷<NUM>=<NUM>. ) It will be understood that to complete a diagnostic analysis using the present system <NUM>, the sensor units <NUM> are moved (relative to the test plate <NUM>) along the rows of wells <NUM>. Using the previously suggested X-Y coordinate system, it would be said that the sensor units <NUM> are moved (relative to the test plate <NUM>) along the X-direction. A most efficient, but not exclusive, movement scenario is diagrammed in <FIG> where the sensor array <NUM> is sequenced along the test plate <NUM> in a straight line hopping fashion.

It may be helpful to think of the plurality of wells <NUM> as being arranged in respective sequence clusters. Each sensor unit <NUM> is associated with a respective one sequence cluster. Thus, in the examples of <FIG> and <FIG>, there are twenty-four sensor units <NUM> in the sensor array <NUM> so that the test plate <NUM> is configured to provide twenty-four distinct sequence clusters. Each reactor section <NUM> is constrained to interact with wells <NUM> in one designated sequence cluster. Or to say it another way, no reaction section <NUM> is permitted to stray outside its designated sequence cluster throughout the duration of a diagnostic test carried out with the system <NUM>. Preferably, but perhaps not necessarily, the wells <NUM> in each sequence cluster will be arranged in a linear array or linear pattern. However, when the sensor array <NUM> has multiple columns of sensor units <NUM>, the wells <NUM> in a sequence cluster will not be contiguous with one another.

To graphically illustrate, attention is directed to <FIG> were a select one of the twenty-four sequence clusters is indicated by bold edging around the mouths <NUM> of the corresponding wells <NUM>. The indicated sequence cluster in <FIG> corresponds to the top-most sensor unit <NUM> in the second or right-hand column of the sensor array <NUM>. (Every other well <NUM> in that same top row of the test plate <NUM> is associated with a different sequence cluster for the top-most sensor unit <NUM> in the first or left-hand column of the sensor array <NUM>. ) Throughout a diagnostic test, the reactor section <NUM> of the top-right sensor unit <NUM> will only descend into a well <NUM> of its designated sequence cluster. No other reactor section <NUM> in the array <NUM> will enter one of the wells <NUM> in the sequence cluster set aside for the top-right sensor unit <NUM>. Thus, the relationship between a sensor unit <NUM> and its designated sequence cluster is exclusive throughout a diagnostic test, to avoid contamination.

Generally stated, the number of sequence clusters in each row of the test plate <NUM> will correspond to the number of columns of sensor units <NUM> in a sensor array <NUM>. If a sensor array <NUM> has only one column of sensor units <NUM> (and when a solitary sensor unit <NUM> is operating solo), a row of wells <NUM> may contain only one active sequence cluster. Or alternatively, if a sensor array <NUM> were to have four columns of sensor units <NUM>, a row of wells <NUM> must contain at least four distinct sequence clusters. And so forth.

<FIG> is a fragmentary top view showing a portion of four rows of wells <NUM> along the bottom edge of the test plate <NUM>, as taken generally along the section line <NUM>-<NUM> in <FIG>. This view helps to illustrate the different roles, or jobs, that the wells <NUM> in any given sequence cluster are required to fulfill. There are at least three jobs that must be fulfilled by the wells <NUM> in any sequence cluster, and therefor at a minimum a sequence cluster must have at least three wells <NUM>. It will be helpful to keep in mind that each row in this example contains two distinct sequence clusters that occupy alternating wells <NUM>. And that for each sequence cluster of wells <NUM>, one sensor unit <NUM> is dedicated. For these reasons, different types of wells <NUM> will appear in matched pairs - one well <NUM> for each sensor unit <NUM> in the two columns.

At least one well <NUM> in each sequence cluster comprises a sample reservoir <NUM>, indicated in <FIG> by diagonal cross-hatch marks. A sample reservoir <NUM> is a well <NUM> that has a particular type of use or function. Not all wells <NUM> in a sequence cluster are sample reservoirs <NUM>. In this example, three sets or pairs of sample reservoirs <NUM> are visible in the fragmented section of <FIG>. The function or job of a sample reservoir <NUM> is to contain liquid reagents or analytes that are required to perform the desired diagnostic test. When the reactor section <NUM> of a sensor unit <NUM> is placed into a sample reservoir <NUM>, the liquid reagents or analytes in that sample reservoir <NUM> are drawn up into the fluid duct <NUM> of the reactor section <NUM>, either by capillary action or under the influence of a pressure differential or combination of both. A more detailed explanation of this procedure will be described below in connection with <FIG>.

Typically, the first well <NUM> in each sequence cluster will be used as a sample reservoir <NUM> specifically to hold a sample taken from a patient (or other source to be tested). As such, it may be useful to configure the test plate <NUM> so that the first, or at least one, sample reservoir <NUM> in a sequence cluster is detachable from the other wells <NUM> in that sequence cluster. In the example of a 12x24 test plate array <NUM> like that shown in <FIG>, a person of ordinary skill in this art can envision the first two columns of wells <NUM> made separable from the remaining wells <NUM> of the test plate <NUM>. Depending on the type of fixture used to support the test plate <NUM> in a diagnostic system <NUM> (e.g., <FIG>), it may not even be necessary that the detachable columns of wells <NUM> be formally joinable or fastenable to the remainder of the test plate <NUM>. In other words, the detachable column(s) of sample reservoir(s) <NUM> could be a permanently loose-piece component that is brought into proximity with the other wells <NUM> in the test plate <NUM> within the system <NUM> at the time of testing. In <FIG>, the separable concept is illustrated via a separation line <NUM>. Such an arrangement, where the sample reservoirs <NUM> used as a repository for the patient sample(s) are detachable from the remainder of the test plate <NUM>, could make the system <NUM> more flexible and more convenient for users.

Another type of well <NUM> is drainage chamber <NUM>. At least one well <NUM> in each sequence cluster will be a drainage chamber <NUM>. Drain chambers <NUM> are dedicated to the drainage of liquid reagents/analytes from the reactor sections <NUM>. Each drainage chamber <NUM> preferably includes an absorbent pad that is capable of wicking liquid reagent from a reactor section <NUM>. Returning to the example of <FIG>, two sets or pairs of drainage chamber <NUM> are seen, and can be identified by stippling, i.e., two drainage chambers <NUM> for each of the two sequence clusters visible in the fragmentary section of <FIG>. In this view, there would very likely be at least one additional (but unseen) pair of drainage chambers <NUM> in each row to accommodate the third set of sample reservoirs <NUM>. Preferably for purposes of motion economy, but not necessarily, one drainage chamber <NUM> will follow each sample reservoir <NUM> in a sequence cluster. One can therefore image that a reactor section <NUM> descends into a sample reservoir <NUM> to uptake liquid reagents or analytes, and then after a suitable incubation period moves to a nearby drainage chamber <NUM> so that its liquid contents can be emptied. Then on to another sample reservoir <NUM>, incubation, another drainage chamber <NUM>, and so on (uptake-incubate-drain) until the required number of steps has been completed. For this reason, one drainage chamber <NUM> will typically follow each sample reservoir <NUM> within any sequence cluster, and furthermore that the sample reservoirs <NUM> in each sequence cluster will tend to be disposed in alternating fashion with the drainage chambers <NUM>, like this: <NUM>-<NUM>-<NUM>-<NUM>-<NUM>-<NUM>.

As shown in <FIG>, it may be possible in some applications to gang-together one or more drainage chambers in a common column. For example, reference number <NUM>' illustrates how all twelve drainage chambers <NUM>' in a single column can be merged. And in cases where the sensor array <NUM> has two (or more) columns of sensor units <NUM>, adjacent columns can be merged into a large common drain chamber <NUM>". Of course, many other variations of this idea are possible.

A third type of well <NUM> in each sequence cluster is a colorant reservoir <NUM>. Each sequence cluster includes at least one, typically only one, colorant reservoir <NUM> at or near the end of the row. The purpose of the colorant reservoir is to contain a liquid color development reagent. After a sensor unit <NUM> has finished its prescribed course of uptake-incubate-drain events, its reactor section <NUM> is plunged into the dedicated colorant reservoir <NUM> in its sequence cluster. After a suitable period of time has been allotted for the color development reagent to have its effect, the sensor unit <NUM> moves to optical detection. After that, the sensor array <NUM> can be trashed with or without performing a final drainage step. In situations where a final drainage step is performed, either a fresh drainage chamber <NUM> or a previously-used drainage chamber <NUM> in the same sequence cluster can be used. (A previously-used drainage chamber <NUM> can be used because contamination will no longer be a significant concern at this stage.

The test plate <NUM> can thus be viewed as an array of wells <NUM> for reagents/analytes and absorbent pads. The array format of the test plate <NUM> aligns with the format of sensor array <NUM> and has at least the same number of columns as the sensor array <NUM>. The reagents/analytes (sample reservoirs <NUM>) and absorbent pads (drainage chambers <NUM>) are arranged alternately starting with the reagents/analytes. The type of reagents and sequence of various reagents can be determined and pre-programmed based on the analyte(s) to test and the type(s) of diagnostic protocol to perform. The last columns are designated for color development reagent.

Optionally, the wells <NUM> can be made as individual pieces, or column sub-sets, or row sub-sets, that are combined like building blocks to form a unitary structure of the desired size. The internal shape of each well <NUM> will be an outside offset of the outer shape of the reactor sections <NUM> so that a loose mated fit is achieved. The offset distance or clearance can, for example, be in the range of about <NUM> to <NUM> (<NUM> to <NUM> inches). The test plate <NUM> can be made any color with transparent, translucent, or opaque material. However, the preferred material is mechanically stable (not easily deformed) and inert to all anticipated reagents/analytes. The test plate <NUM> can be manufactured by injection molding if a plastic material (e.g., polypropylene) is chosen. Wells <NUM> can be manufactured all at once into a fully-formed test plate <NUM> or can be assembled by placing different components (e.g., rows or columns) together.

<FIG> schematically illustrate the flow mechanism of reagents/analytes into and out of the reactor section <NUM> of a single optofluidic sensor unit <NUM> in the aforementioned uptake-incubate-drain course of events. For clarity, mating wells <NUM> are not shown in any of <FIG>. It should again be mentioned that the leading tip of the reactor sections <NUM> are shown in an flat (non-tapered) configuration not falling under the scope of the invention in these <FIG>.

<FIG> represents a reactor section <NUM> that is inserted or loaded into a well <NUM> configured to function as a sample reservoir <NUM>. A directional arrow at the bottom end <NUM> of the fluid duct <NUM> shows the flow direction of the reagents/analytes at the open bottom end <NUM> of the single optofluidic sensor unit <NUM>. When the reactor section <NUM> of the sensor unit <NUM> is immersed into a sample reservoir <NUM> containing a reagent/analyte solution, the solution flows up into the reactor section <NUM>, because of the capillary force or because of a pressure differential induced at the top end <NUM> or combination of both. In one example, a pressure differential is accomplished by gently pulling a vacuum through a feed tube <NUM>. This corresponds to the "uptake" part of the uptake-incubate-drain process.

<FIG> corresponds to the "incubate" part of the uptake-incubate-drain subroutine. The solution drawn into the reactor section <NUM> is incubated in the fluid duct <NUM> for a certain amount of time to allow the interaction between the solution and reactive coating agent A (<FIG> and <FIG>) pre-applied to the interior hollow surface within the reactor section <NUM>. Or as mentioned previously, the reactive coating agent A could alternatively be immobilized using the system <NUM> of this invention in a pre-test preparation phase.

<FIG> portrays the "drain" part of the uptake-incubate-drain cycle. After incubation, the solution contained within the reactor section <NUM> is drained out through the bottom end <NUM>, as indicated by the downwardly-pointing directional arrow. Typically, the solution is wicked away using an absorbent pad located inside a drainage chamber <NUM>, or alternatively using a pressure differential induced through the top end <NUM> of the fluid duct <NUM> or combination of both. In one example, a pressure differential is accomplished by gently pushing air through a feed tube <NUM>. After draining the solution, biochemical molecules <NUM> (<FIG> and <FIG>) are attached on the hollow surface within the reactor section <NUM>. The processes of injecting the solution (<FIG>), incubating the solution (<FIG>), and draining the solution (<FIG>) can be repeated sequentially as per requirements of the diagnostic protocol.

In the last step associated with the test plate <NUM>, portrayed in <FIG>, the reactor section <NUM> of the optofluidic sensor unit <NUM> is immersed into color development reagent held in a colorant reservoir <NUM> located at or near the last columns of the test plate <NUM>. Via capillary action or pressure-assist or combination of both, the color development reagent colorant fills the reactor section <NUM> and then is subsequently drained after a suitable incubation period or remains inside sensor unit <NUM> after a suitable incubation period. Some protocols require that the colorant does not need to be drained out. For example, in chemiluminescence measurement, the color development reagent remains inside the reactor section <NUM>. The colorant prepares the biochemical molecules <NUM> for optical detection. The processes of coloring the biochemical molecules <NUM> can be repeated as per requirements of the diagnostic protocol.

After that, the fully prepared sensor unit <NUM> is ready for optical detection. To facilitate the optical detection process, the system <NUM> of this invention may, optionally, include an optical detection cartridge <NUM>. Perhaps best seen in <FIG>, the optical detection cartridge <NUM> includes a plurality of light confinement isolation booths <NUM>. The number and arrangement of isolation booths <NUM> correspond to the number and arrangement of sensor units <NUM>. That is to say, the array format of the optical detection cartridge <NUM> must be capable of aligning with the format of the sensor array <NUM>, and therefore it is desirable that the detection cartridge <NUM> have the same number of columns as the sensor array <NUM>. Each isolation booth <NUM> has a booth height defined by an open ceiling <NUM> and a closed floor <NUM>. Within the cartridge <NUM>, each isolation booth <NUM> will typically have the same, i.e., generally equal, booth height. Each isolation booth <NUM> is characterized by having an open viewport <NUM> surrounded by optically-opaque sides. Similar to the loose mating fit between sensor array <NUM> and test plate <NUM>, the fit between the sensor array <NUM> and the optical detection cartridge <NUM> must also be of a somewhat slack male-female relationship. The internal shape of each isolation booth <NUM> will be an outside offset of the outer shape of the reactor sections <NUM> so that the desired loose mated fit is achieved. The offset distance or clearance can, for example, be in the range of about <NUM> to <NUM>(<NUM> to <NUM> inches).

Each isolation booth <NUM> is adapted to receive therein a respective reactor section <NUM>, so that the observation face <NUM> of the reactor section <NUM> is oriented toward the viewport <NUM>. In particular, each isolation booth <NUM> is configured to receive the reactor section <NUM> of a sensor unit <NUM> through its open ceiling <NUM>. When fully inserted, the observation face <NUM> of the reactor section <NUM> is exposed, i.e., visible, through the viewport <NUM>, as shown in <FIG>. In this manner, the observation face <NUM> is presented for optical detection. To avoid optical cross talk, the optical detection cartridge <NUM> is made with an opaque (preferably black) and mechanically stable material. The optical detection cartridge <NUM> can be manufactured by injection molding if a plastic material (e.g., back opaque polystyrene) is chosen.

An optical detector <NUM> has at least one (typically only one) detection lens <NUM> associated with each isolation booth <NUM>. In the example of <FIG> and <FIG>, two optical detectors <NUM> are provided, each having twelve lenses <NUM>. One optical detector <NUM> is provided for capturing the optical conditions of the sensor units located along the first (left-hand) column of the sensor array <NUM>. Conversely, the other optical detector <NUM> is provided for capturing the optical conditions of the sensor units located along the second (right-hand) column of the sensor array <NUM>. Each detection lens <NUM> of the optical detector <NUM> is arranged opposite the viewport <NUM> of a respective the isolation booth <NUM> or is otherwise moveable into such a position. Of course, another possible variation is that a single optical detector <NUM> is configured with only one lens <NUM> for recording optical signals from all twelve sensor units <NUM>, either sequentially or concurrently or one snapshot using large field of view lens. Whether plural or singular detection lenses <NUM> are employed, the opaque detection cartridge <NUM> makes optical cross-talk preventable among individual optofluidic sensor units <NUM>, thus enabling improved accuracy in chemiluminescence or fluorescence detection schemes if desired.

By fashioning the observation face <NUM> as a flat planar surface oriented orthogonally toward the lens <NUM>, an ideal imaging condition is established with which to acquire a uniform, relatively evenly distributed optical color representation of the biochemical molecules <NUM>. As previously mentioned, the cross-sectional thickness of optically transmissive material directly behind the observation face <NUM> is configured in the form of a plano-concave lens as shown by the cross-sections in <FIG> and <FIG>. Plano-concave lens are naturally divergent, which has the benefit of helping to spread the color-affected light across the observation face <NUM>, thus increasing the efficiency, sensitivity and effectiveness of the optical detector <NUM>.

<FIG> illustrates the relative movement of the sensor array <NUM> over the test plate <NUM> and finally to the optical detection cartridge <NUM>. As also described in the legend provided with <FIG>, solid arrows <NUM> represent relative moving directions of the sensor array <NUM> into sample reservoirs <NUM> containing liquid reagents. Evenly dotted arrows <NUM> represent relative moving directions of the sensor array <NUM> from sample reservoirs <NUM> into drainage chambers <NUM>. Typically, an absorbent pad will be located at the base of each drainage chamber <NUM>. This process may be repeated through multiple sample reservoirs <NUM> based on the required diagnostic protocol. A dot-dash arrow <NUM> represents relative movement of the sensor array <NUM> into the color development reagent contained with the final colorant reservoirs <NUM>. Optionally, not shown, the sensor array <NUM> may be drained after incubating in the color development reagent. Evenly dashed arrow <NUM> represents final movement of the sensor array <NUM> into the optical detection cartridge <NUM>, where the isolation booths <NUM> confining light contamination between the sensor units <NUM> (i.e., undesirable optical cross-talk). Optical detectors <NUM> are poised to take readings from each observation face <NUM>, which reading are transmitted to an appropriate computerized processing device (not shown) for analysis and reporting.

<FIG> demonstrates, in simplified fashion, an exemplary automated optofluidic diagnostics system <NUM> combining the three main assembled components: the sensor array <NUM>, the test plate <NUM>, and the optical detection cartridge <NUM>. A suitable transfer mechanism <NUM> is operatively disposed between the sensor array <NUM> and the test plate <NUM> and the optical detection cartridge <NUM> for moving the sensor array <NUM> relative to the test plate <NUM> and the optical detection cartridge <NUM> in response to a pre-programmed pattern. In this example, the sensor array <NUM> is gripped by a robotic arm attached to a stepper or servo motor. Feed tubes <NUM> connect to computer-controlled pressure differential device(s). The robotic arm can be moved vertically using the motor, while the entire module of the robotic arm, the feed tubes <NUM>, the motor and sensor array <NUM> can be moved horizontally using another stepper motor. In this example, the test plate <NUM> and the optical detection cartridge <NUM> are fixed on a stationary fixture. For simplicity the optical detectors <NUM> are not shown in <FIG> but could of course be mounted on flanking sides of the optical detection cartridge <NUM> on the fixture as in <FIG>, or else supported on a separate robotic arm and moved into position when needed. All these parts and modules may be enclosed in an enclosure. A touch screen user access interface (not shown) connected to a suitable microcontroller can be located at any convenient location on or around the enclosure.

In other contemplated embodiments, a robotic arm moves the plate <NUM> while the sensor array <NUM> remains stationary.

Naturally, <FIG> represents but a simple desk-top configuration of the system <NUM>. Those of skill in the art will readily appreciate that the system <NUM> described herein can be scaled-up to include other parts such as automated sample additions to the test plate <NUM>, stacking modules for automated insertions, automated ejections and automated re-loadings of sensor arrays <NUM>, test plates <NUM> and/or optical detection cartridges <NUM>. Likewise, the system <NUM> could also be scaled-down to a partially or fully manual process with only one or a small number of sensor units <NUM> processed at a time.

In examples not falling under the scope of the invention, the shape of the leading tip of the reactor section <NUM> can take different forms. Similarly, the shape of the base <NUM> of the wells <NUM>, and in particular the bases <NUM> of the sample reservoirs <NUM>, can also vary. In <FIG> and <FIG>, the leading tip is presented as a flat, squared-off shape. A flat tip is adequately functional within the system <NUM> but has one slight disadvantage - a flat tip naturally forms a relatively large hanging droplet of reagent solution as shown in <FIG>. As the hanging droplet does not enter the fluid duct <NUM>, it does not contribute to the diagnostic test and therefore represents an unproductive quantity of reagent solution. Often, the quantity of reagent solution may be limited, and it is necessary to economize usage. Comparing <FIG>, it can be seen that a larger droplet size of reagent solution (as collected from a sample reservoir <NUM> or colorant reservoir <NUM>) will be greater for the flat tip than for the conical tip. Thus, in some applications it may be preferable to form the leading tips <NUM> of the reactor sections <NUM> with a generally frustoconical converging shape like that exemplified in <FIG>, <FIG> and <FIG> which naturally forms a relatively small hanging droplet of reagent solution.

Further economies can be achieved by optimizing the shape of the base <NUM> of each well <NUM>, or at least those wells <NUM> serving as sample reservoirs <NUM>, to closely match a conical leading tip <NUM>. <FIG> depicts a flat tipped reactor section <NUM> like that of <FIG>. The base <NUM> of the well <NUM> in this example is matched with a complementary flat shape. As a result of these mating flat shapes and exacerbated by the relatively large size hanging drop carried by the flat leading tip of its reactor section <NUM>, a pronounced meniscus is formed by the molecules of the liquid that are attracted to climb the container walls. The quantity of unproductive solution would be even worse if the base <NUM> were to have a conical shape while the leading tip of the reactor section <NUM> remained flat. However, the situation can be vastly improved by tapering the base <NUM> with a complementary conical shape to the tapered leading tip <NUM> of the reactor section <NUM> as shown in <FIG>. The shaded area shows a minimum amount of solution required for capillary uptake in this case. According to the invention and for maximum efficiency, the base <NUM> has a diverging square-to-round shape that exactly complements the generally frustoconical converging shape of the leading tip <NUM> of the reactor section <NUM>. In other words, the lofted boss square-to-round shape of the leading tip <NUM> is matched by the lofted cut square-to-round shape of the base <NUM>, resulting is a very small quantity of unproductive reagent solution being trapped at the interface. Consequently, the minimum amount of reagent solution will be required for capillary uptake when both the leading tip <NUM> and base <NUM> have matched conical configurations like that shown in <FIG>.

The present disclosure describes a complete automated optofluidic diagnostic system <NUM> and accompanying methods designed for rapid analyte detections without using a conventional microplate reader or conventional well-plate. The system <NUM> comprises three independently usable components: an optofluidic sensor array <NUM>, a test plate <NUM> having pre-populated sample reservoirs <NUM> and drainage chamber <NUM>, and an optical detection cartridge <NUM>. In one embodiment described, the sensor array <NUM> is attachable to and detachable from a robotic arm with two degrees of freedom, movable vertically and horizontally, while the test plate <NUM> and optical detection cartridge <NUM> are residing at stationary positions. In addition, the system <NUM> is able to integrate the user's desired optical detection module (e.g., chemiluminescence, fluorescence, etc.) with or without the stacking modules for high-throughput testing. The envisioned overall system <NUM> volume can be designed to occupy less than <NUM> cubic foot, making it conveniently portable. The user is able to access and control the system <NUM>, while also being able to see the status of the system via a touch screen interface (not shown).

The alternative 12x24 matrix test plate <NUM> shown in <FIG> illustrates an optional setup in which the first two columns of sample reservoir(s) <NUM> are formed as a loose-piece component that is brought into proximity with the other wells <NUM> in the test plate <NUM> along a separation line <NUM>. This type of an arrangement makes it convenient for the initial column(s) of sample reservoirs <NUM> to be used for patient sample gathering. As such, it is potentially beneficial that these leading columns be disconnected, at least initially, from remainder of the test plate <NUM>.

While a portable system <NUM> (i.e., smaller than <NUM> cubic foot) may be desirable for many users, in other contemplated embodiments the system <NUM> can be scaled up to include other parts such as automated sample additions to the test plate <NUM>, and stacking modules of automated insertion, ejection, and re-loading of sensor array <NUM>, test plate <NUM>, and optical detection cartridge <NUM> to name but a few.

Claim 1:
A sensor unit (<NUM>) for an optofluidic diagnostic system (<NUM>) configured for sequential movement into and out of registry with a plurality of discrete wells (<NUM>) along a vertical path, said sensor unit (<NUM>) comprising:
a top end (<NUM>), a bottom end (<NUM>) spaced vertically from said top end (<NUM>),
a single fluid duct (<NUM>) extending continuously from said top end (<NUM>) to said bottom end (<NUM>),
a reactor section (<NUM>) adjacent said bottom end (<NUM>), said fluid duct (<NUM>) including a reactive coating agent immobilized over at least a portion thereof in said reactor section (<NUM>),
said reactor section (<NUM>) having an outer geometric shape comprised of a plurality of exterior faces surrounding said fluid duct (<NUM>), one of said exterior faces comprising a planar observation face (<NUM>), at least a portion of said planar observation face (<NUM>) being fabricated from an optically transmissive material, said fluid duct (<NUM>) being generally cylindrical whereby the portion of said reactor section (<NUM>) between said duct (<NUM>) and said observation face (<NUM>) comprises a generally plano-concave lens, and
said outer geometric shape of said reactor section (<NUM>) being centered about said fluid duct (<NUM>), said reactor section (<NUM>) having a leading tip (<NUM>) formed directly adjacent said bottom end (<NUM>) of said duct (<NUM>), said leading tip (<NUM>) having a square-to-round lofted blend transition.