WO2012127433A1

WO2012127433A1 - A microfluidic system for automating pathological test procedures

Info

Publication number: WO2012127433A1
Application number: PCT/IB2012/051360
Authority: WO
Inventors: Debapriya CHAKRABORTY; Sushant Gupta; Suman CHAKRABORTY
Original assignee: Chakraborty Debapriya; Sushant Gupta; Chakraborty Suman
Priority date: 2011-03-24
Filing date: 2012-03-22
Publication date: 2012-09-27

Abstract

A microfluidic system for automating pathological procedures comprises a platform (1) rotatable in predetermined direction. The system includes plurality of discs (5). These discs (5) are stacked together to form multilayered disc (5) and at least one hole is provided at centre of each disc (5). The multilayer disc (5) formed is mounted on the platform (1). Further, the system is provided with source reservoir (2) and destination reservoir (4) on one of the layer of the multilayer disc (5) which retains sample fluid and resultant fluid respectively and is connected to each other through micro-channel (3). In addition, the system includes plurality of chambers which are formed on one of the layer of multilayer disc (5), wherein said chambers are configured for retaining reagents. Further reagents from these chambers are supplied to fluid sample through micro-channel (3). An optical detector is configured to detect predetermined characteristic of resultant fluid.

Description

"A MICROFLUIDIC SYSTEM FOR AUTOMATING PATHOLOGICAL

TEST PROCEDURES"

TECHNICAL FIELD

The subject matter disclosed herein relates to a micro fluidic system and a method for automating pathological process. More particularly relates to disc shaped microfluidic platform system and a method for automating pathological process.

BACKGROUND OF THE DISCLOSURE

Traditionally, pathological procedures have been fairly manual. The laboratory personnel measure a certain amount of fluid in a pipette, transfer it to a test tube, then do this for another chemical, mix them and shake the test tube for getting a resultant fluid. That makes one step. For a typical test like Widal which is widely used for typhoid diagnosis in India, this is done 58 times. In India, about 350 million tests are conducted every year.

This system is very inefficient because skilled laboratory personnel have to do repetitive procedures again and again. Since humans cannot deal with small quantities of fluid, they end up using a lot of chemicals. Use of bulky apparatus like test tubes, flasks, retorts etc. significantly increases the cost of the test. As is evident, the current procedures of testing involve wastage of time, money and resources.

Recently, many automated techniques have made inroads into the Indian laboratories. Unfortunately, all of these are way too expensive, too bulky and/or are inefficient towards usage of chemicals. All these machines involve use of sensors and mechanical aids such as robotic arms that result in increased costs, occupy a lot of space, involve naive programming skills and require high maintenance. The high pathological lab costs are a deterrent for proper medical care to millions of patients all over the country.

Hence, there exists a need to develop a system, which reduces testing procedure time, is economical, makes use of less resources and importantly easy to use and maintain. Further, the space required to place the system should be less and it should be compact.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a system and a method as described in the description. The subject matter disclosed herein solves the limitations of existing arts by providing compact and easy to use device which make use of less resources and reduces time required to conduct a test procedure.

Additional features and advantages are realized through various techniques provided in the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered as part of the claimed disclosure.

In one non-limiting exemplary aspect, there is provided a microfluidic system for automating pathological procedures. The system comprises a platform (1) rotatable in predetermined direction. The system further includes plurality of discs (5). These discs (5) are stacked together to form multilayered disc (5) and at least one hole is provided at centre of each disc (5). The multilayer disc (5) so formed is mounted on the platform (1). Further, the system is provided with source reservoir (2) of predetermined shape formed on one of the layer of the multilayer disc (5) wherein the source reservoir (2) receives fluid sample. In addition to above, the system includes plurality of chambers of predetermined shape which are formed on one of the layer of the multilayer disc (5), wherein said chambers are configured for retaining reagents and these chambers are connected through a micro-channel (3) formed on one of the layer of the multilayer disc (5). Also, the system is provided with destination reservoir (4) of predetermined shape which is formed on one of the layer of the multilayer disc (5), wherein said destination reservoir (4) is connectable to the source reservoir (2) through the micro-channel (3) and is configured to collect resultant fluid. An optical detector is configured to detect predetermined characteristic of resultant fluid.

A method for performing pathological test procedures is disclosed as another aspect of the disclosure. The method comprises placing a multilayered disc (5) on a rotatable platform (1). Once the multilayer disc (5) is placed on the platform (1), fluid samples and reagents of predetermined amount is introduced into source reservoir (2) and plurality of chambers formed on one of the layer of the multilayer disc (5) and reagents into plurality of chambers formed on one of the layers of the multilayer disc (5) . Further, upon introduction of fluid sample and reagents, the multilayered disc (5) is rotated at a predetermined speed. The rotatable disc (5) would cause mixing of fluid samples with the reagents inside a microfluidic channel. Once, the operation of mixing is completed, a resultant fluid is obtained as a result of the mixing operation and is stored in destination reservoir. Now, characteristics of the resultant fluid are determined using the optical detector to complete the pathological test procedure.

In another non-limiting exemplary aspect, there is provided a method of manufacturing a microfluidic system for automating pathological test procedures. The method comprises machining patterns (6) on polycarbonate (P) disc (5) and adhesive layers (A). At least one hole is made at centre and periphery of each of the layer. Once this is done, all the layers are staked together to form a multilayer disc (5) by aligning the hole (7) formed at the periphery of each layer; and later the disc (5) is mounted on a platform (1).

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

The novel features and characteristic of the disclosure are set forth in the appended claims. The embodiments of the disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings and in which:

Figure 1 shows interplay of forces on the outlined microfluidic platform (1) and shows a disc (5) rotating with angular velocity ω. FS_T, F_D, F_R, FC in the figure represent surface tension, viscous drag, centrifugal force and coriolis force.

Figure 2 shows isometric and side views of the microfluidic platform (1) and also illustrates mounting of the disc (5) on a drive motor.

Figure 3 shows Layers P, A, P, A, P from left to right (P: Polycarbonate layer, A: adhesive layer). All of these are stacked together to give a rotating disc (5). Patterns (6) and reservoirs are designed on the three internal discs (5) to obtain predetermined fluid motion. Figure 4 illustrates manual washing procedure for a typical test like Widal. Each circle represents a test tube. Reagents are diluted serially till a desired concentration is reached.

Figure 5 shows a portion of the disc (5) showing the washing procedure using the system. In contrast to the procedure shown in Fig. 4, reagents get transferred automatically (by interplay of forces on a rotating platform (1)) from the source reservoir (2) near the centre to the destination reservoir (4) near the rim of the disc (5).

Figure 6 shows a portion of the disc (5) showing an integrated series of mixing operation taking place in the system.

Figures 7 and 8 illustrate the configuration of disc (5) showing the micro-channel (3) along with the direction of the motion of the disc (5) and fluid sample.

Figure 9 illustrates the photographic image of the configuration of disc (5) showing the micro-channel (3).

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

It is to be noted at this point that all of the above described components, whether alone or in any combination, are claimed as being essential to the invention, in particular the details depicted in the drawings and reference numerals in the drawings are as given below.

The subject matter disclosed herein relates to a microfluidic system and a method for automating pathological process.

In one embodiment, the present disclosure provides an aid for faster pathological detection with reduced cost by minimising human interventions and reduction in usage of chemicals and other ingredients by integrating liquid interfacing and detection units as well as means for quality control. A patient's samples for an example, urine, blood, sputum, etc. can be inserted through designated incisions into the system developed. Then this is transported and manipulated in a rapid, efficient and controlled manner to the designated reservoir. This replaces the conventional technique of conducting pathological tests using bulky retorts, tubes, flasks etc. In one embodiment, the disclosure provides the device which is capable of carrying a multiple tests in every cycle apart from catering to a large number (70%) of diagnostic tests.

The disc (5) containing microfluidic channels are fabricated by using a lamination technique by stacking polycarbonate discs (5) using pressure sensitive adhesive film layers. Various diameters of milling bits and drill bits are utilized for the computer numerical control (CNC) micromachining. This can also be achieved using laser. The CNC-machined disc (5) system consists of three polycarbonate discs (5) and two pressure sensitive adhesive layers. The three polycarbonate discs (5) constitute the top plate, the middle plate and the bottom plate of the five layer disc (5) assembly. Each of these polycarbonate discs are bonded by pressure sensitive adhesive layers in which micro-channel (3) is cut by a vinyl cutter or computer plotter or laser. These channels are aligned with the connecting reservoirs located on the polycarbonate discs (5) through the alignment holes, and the entire five-layer system is then press-bonded. In one embodiment, the apparatus or platform (1) of the present disclosure helps in reducing the use of consumables required for pathological detection, such a platform (1) can substitute the standard consumables like glass slides, centrifuge tubes and microwell plates. Disc (5) based platform (1) is efficient in integrating different steps in a non-intrusive manner. In one embodiment, a variety of operations including valving, separation, mixing, heating and optical detection can be carried out in the integrated platform (1). The device is very suitable for use in pathological laboratories and rural healthcare centers as it requires unskilled to semi-skilled labor for operation. Apart from minimizing the human intervention and improving efficiency, it decreases the costs by up to 40%.

In one embodiment, the platform (1) of the present disclosure is helpful in eliminating centrifuge as it essentially uses centrifugal force to drive the flow. Different fluidic operations like mixing, valving, separation can be easily integrated under single platform (1). Multiplexing different operations can be easily performed in a disc (5), which implies a single disc (5) may be used to perform several tests from a single blood sample. As this platform (1) does not require much human intervention, it can be easily used to cater to the needs of the rural India, where skilled labour and sophisticated instruments are not available. In one embodiment, the pathological test procedures, being automated, will be more reliable and effective. The chemicals used will be drastically less as compared to the current techniques and will result in enormous reduction in the costs of the test. Current pathological techniques involve use of bulky apparatus as they deal with macro quantities of chemicals. The aforementioned apparatus offers a compact solution by dealing with micro quantities of chemicals. This replaces the conventional technique of conducting tests using bulky retorts, tubes and flasks. Lab personnel time is saved by semi-automation which can be used in enhancing the capacity of the lab.

Fig. 1 illustrates interplay of pathway thickness and rotation speed to realise the motion of fluid from one chamber to another. Centrifuge is inherently built in by virtue of the nature of the platform (1). All these can be attributed as interplay of four distinct forces on a rotating platform (1) namely, coriolis force, centrifugal force, viscous drag and surface tension. These forces in turn are controlled by two factors: rotational speed and design of the incisions and reservoirs on the disc (5). Fig. 2 illustrates an apparatus that exploits micro fluidic platform (1) to automate diagnostic tests. The disclosure provides a diagnostic tool that exploits a combination of centrifugal, coriolis, viscous drag and surface tension forces to manipulate chemical reagents and patient samples and to carry out pathological procedures in an automated fashion.

Structural details of micro fluidic platform (1) are illustrated in Figs. 3 and 9. In one exemplary embodiment, the platform (1) consists of a five layered two-sided polycarbonate disc (5). A single disc (5) is shown in the figure. 9. The disc (5) is made up of acrylic or polycarbonate (P) and two-sided Flex Mount adhesive layer (A). These layers are designed and stacked together in five layers viz. P, A, P, A, P in the order of occurrence. The P and A layers consist of several user-defined patterns (6) to enable deliver the fluids from one chamber to another. These patterns (6) can support multiple diagnostic tests on a single disc (5) that provide to the same or different symptom.

In one embodiment, the structure further includes the drive that consists of an optical detector and an encoder motor. The motor is controlled by AVR 40 Pin Rapid Robot Controller Board (ATMega32) using Pulse Width Modulation (PWM) or Proportional- Integral-Derivative (PID) controller. The micro fludic platform is rotated in a predetermined speed. The speed in which the micro fludic platform operates ranges from 5rpm to 3000rpm. Each diagnostic test has a distinct series of programmed steps that execute when a particular test is chosen from the bundled computer software or an option in the motor hardware itself. An optical detector (colorimetric analyser or a high speed camera) can move along a radius of the disc (5) and gather visual information about the reagents within the disc (5). The images can further be processed and useful conclusions be made therein. Figures 4, 5 and 6 of the disclosure illustrate the microfluidic operations. Several different fluid operations that are required in a pathological test can be integrated in a series or parallel fashion on the aforementioned disc (5). These operations include but are not limited to mixing, separation, valving, centrifuging, heating and optical detection. Mixing involves fluids in two or more reagent chambers which come together in a common pathway leading to a destination reservoir (4), mix together while flowing and get collected in the target reservoir. In an exemplary embodiment, manual washing procedures for a typical test like Widal is illustrated in figure 4. In figure 4, each circle represents a test tube. Reagents are diluted serially as shown till a desired concentration is reached. In contrast to this procedure, in Fig. 5, reagents get transferred automatically (by interplay of forces on a rotating platform (1)) from the reservoirs near the centre to the reservoirs near the rim.

Fig. 7 illustrates the view of microchannel connecting the source and destination reservoir (4). In one embodiment the disclosure provides a microfluidic system for controlled generation and manipulation of microbubble. Bubbles of micrometer length scales have scientific and technological implication, primarily to emerging applications in the fields of food processing, targeted drug delivery, ultrasound imaging, heavy metal removal during mineral processing, development of bubble based logic circuits, and controlled release of chemicals. The present disclosure additionally exploits the effects of the forces due to angular acceleration as well, for tuning the flow features. Frequency and dimensions of the bubbles generated may be explicitly controlled by designed variations of the rotational speeds for a given combination of fluids and dimensions of the pertinent fluidic pathways.

Fig. 8 illustrates the system in analysing anomalous mixing behaviour. The characteristics of two-fluid mixed in T-shaped microchannel is analysed using a rotating platform (1). Three regimes of mixing were identified based on the distinct flow behaviour. A diffusion based mixing regime was obtained for low rotation speeds. A coriolis force based mixing regime was observed for intermediate rotation speeds. At very high rotation speed, flow instability based mixing regime was observed. Some techniques utilize mechanical pulsation of the fluids to create change in the flow pattern, wherein chaotic flows are induced to the flow. Specific geometries of microchannel are used to obtain different flow rates and different combination of samples.

In one embodiment the present disclosure provides the CD based platform which can perform efficiently for wide variety of samples. Also, wide range of flow rates can be obtained just by varying the rpm of the motor and many identical operations can be easily implemented. In addition the polymeric materials used in micro fludic platform (1) are amenable to mass production.

In one embodiment, the disclosure provides an improved qualitative and quantitative insight regarding interplay of the related physical parameters governing the centrifugal capillarity, including a dynamical evolution of the contact line motion, by employing a simplistic approach that compares well with both rigorous full-scale numerical predictions as well as with the experimental findings. In this disclosure the physics of centrifugally filling mechanisms for disc (5) based microfluidic applications is analysed. Centrifugal force is the primary driving force for the capillary front with surface tension effects aiding it, resisted by the opposing viscous forces. However, if the capillary is hydrophobic, the surface tension opposes the motion of the liquid front. In the present study, the capillary is made hydrophilic and hence surface tension aids the motion. The competing effects of the driving and the retarding forces effectively determine the displacement, velocity and acceleration characteristics of the capillary front. The manufacturing procedure of microfluidic platform (1) of the present disclosure is explained in detail herein. Firstly, a design of each layer of the disc (5) is worked out in AutoCAD/Solidworks. The design of each layer is then aligned and matched to get a fitting. Further, table-top CNC or laser is used to realise the patterns (6) on P layers. A vinyl cutter or laser is used to do the same for T layers. Apart from the central hole (to make it a disc (5), a small hole (7) is made near the periphery of each of the layers to restrict the degree of motion of these layers and to ensure proper alignment.

The method of detection includes the procedure of inserting the fluid through the inlet, so that it does not fill the capillary with the aid of surface tension only. A high speed camera was used to capture the images for different stroboscopic sequences (only for the laboratory purpose experiments). When the same position of the disc (5) passed under the camera, the strobe was triggered. Since the disc (5) spun at the same rate at which the strobe light was triggered, a fixed position of the disc (5) was highlighted in each turn. The images of the partially filled capillaries could be captured via the camera and were subsequently transferred to a computer for data storage.

In one embodiment, the platform (1) disclosed in the present disclosure saves chemicals used in the test. For example, the platform (1) saves 83.33% of chemicals required or carrying out test procedure and thus saving the cost

In one embodiment, the platform (1) of the present disclosure is completely automated. Therefore, no expenditure on personnel for doing the above mentioned steps and thus saving considerable amount of time.

In one embodiment, the disclosure helps in reducing cost for conducting a test by about 38%o to existing test procedure.

The microfludic platforms discussed herein can be used for various operations and few of them have been listed herein which are capillary test strips, lateral flow assays, "the microfludic large scale integration" approach, centrifugal microfludics, the electrokinetic platform, pressure driven droplet based microfludics, electrowetting based microfludics, SAW driven microfludics and "free scalable non-contact dispensing". Also, the present disclosure can be used to study the fluid dynamic characteristics of a fluid for eg. The capillary filling dynamics in centrifugally actuated microfludic platforms with dynamically evolving contact line motion for wetting fluids, etc. Hence, a person skilled in art can infer that the microfludic platform can be utilized for conducting various operations. Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims

Claims

We Claim:

1. A micro fluidic system for automating pathological test procedures comprising

a platform (1) rotatable in predetermined direction;

plurality of discs (5) stacked together to form multilayer disc (5) and at least one hole provided at centre of each disc (5), wherein the multilayer disc (5) is mounted on the platform (1);

at least one source reservoir (2) of predetermined shape formed on one of the layers of the multilayer disc (5), wherein the source reservoir (2) is configured to receive fluid sample;

plurality of chambers of predetermined shape formed on one of the layers of the multilayer disc (5), wherein the chambers are configured for retaining reagents and are connectable through one or more micro-channels (3) formed on one of the layers of the multilayer disc (5);

at least one destination reservoir (4) of predetermined shape formed on one of the layers of the multilayer disc (5), wherein said destination reservoir (4) is connectable to the source reservoir (2) through another micro-channel (3) and is configured to collect resultant fluid; and

an optical detector configured to detect predetermined characteristic of resultant fluid.

2. The system as claimed in claim 1, wherein the channel is provided with different variation in its width and length, which serves as valves for the channels.

3. The system as claimed in claim 1, wherein the channels are provided at an equal distance from the center of the disc (5) and has predetermined storing capacities.

4. The system as claimed in claim 1, wherein each layer of disc (5) is provided with a hole (7) near its periphery to align the layers with one another.

5. The system as claimed in claim 1, wherein said chamber is of predetermined shape to store predetermined quantities of fluids and control the flow rate.

6. The system as claimed in claim 1, wherein an image capturing means is provided to capture the images of resultant fluid.

7. The system as claimed in claim 1, wherein a computing device is provided for receiving images captured and processing them to make conclusions about the results.

8. The system as claimed in claim 1, wherein the rotatable platform (1) is mounted on a motor accompanied with a control system.

9. The system as claimed in claim 1, wherein the motor is controlled by microprocessor using at least one of Pulse Width Modulation (PWM) and Proportional-Integral- Derivative (PID) controller.

10. The system as claimed in claims 1, wherein the disc (5) is made up of transparent material which is alternatively stacked using adhesive between each disc (5) to form a multilayered disc (5).

11. The system as claimed in claim 1 , wherein the polycarbonate layer is selected from a group comprising polycarbonate and acrylic.

12. The system as claimed in claim 1, wherein the adhesive layer is selected from a group comprising polyester tapes and double-sided adhesive.

13. The system as claimed in claim 1, wherein the optical detector moves along a radius of the disc (5) and collects required visual information about the resultant fluid.

14. A method for automating pathological test procedures, said method comprising acts of:

placing a multilayered disc (5) on a rotatable platform (1);

introducing fluid samples into source reservoir (2) and reagents into plurality of chambers on the multilayered disc (5) respectively;

rotating the multilayered disc (5) to a predetermined speed;

mixing fluid samples with the reagents inside a microfluidic channel(3) to obtain a resultant fluid;

storing the resultant fluid in destination reservoirs; and

detecting visual information about the resultant fluid.

A method of manufacturing a microfluidic system for automating pathological test procedures, said method comprising acts of machining patterns (6) on polycarbonate (P) and two-sided adhesive layers (A);

making hole at centre and periphery of each of the layer;

stacking all the layers to form a disc (5) by aligning the hole (7) provided at the periphery of each layer; and

mounting the disc (5) on platform (1).

16. The method of manufacturing as claimed in claim 15, wherein the patterns (6) formed are of predetermined shape and size.