Patent Application
20160089670
A wide variety of systems and methods exist for performing biochemical analysis, for example for medical testing. A common technique is to load analytes and reagents into a microfluidic “chip” that has fluid flow channels and other structures formed in it using photolithography techniques. Such a chip may include pumps, reservoirs, valves, mixing structures, and other features useful in the performance of a certain tests.
Typically, such a chip is controlled by an external controller, through application and release of fluid pressure at key points in the chip. For example, a valve may be formed by crossing a fluid flow channel in a soft medium with a dead-end cross channel. By pressurizing the cross channel, the fluid flow channel can be pinched off, and by releasing the pressure in the cross channel, the fluid flow channel is allowed to re-open. A peristaltic pump may be formed by placing three or more such valves close together crossing a fluid flow channel in a soft medium. By sequentially pressurizing and depressurizing the valves channels to pinch off and re-open adjacent locations in the fluid flow channel, fluid can be caused to flow in the fluid flow channel.
Because of the need for external control, such microfluidic chips are not convenient for use in routine medical testing, especially in remote locations.
According to one aspect, a system for fluid manipulation comprises a composite wafer having a flexible layer and a substantially rigid layer adhered to the flexible layer. The flexible layer defines one or more recesses that are covered by the substantially rigid layer to form one or more reservoirs, and the flexible layer defines one or more fluid channels among the one or more reservoirs. The system further comprises a movable compression device in contact with the flexible layer. The movable compression device is configured to progressively compress the flexible layer such that when the movable compression device traverses the flexible layer, fluid is forced through the one or more fluid channels and the one or more reservoirs in a sequence determined by the layout of the one or more fluid channels and the one or more reservoirs. In some embodiments, the movable compression device is a roller. The movable compression device may be a cylindrical roller. The movable compression device may be a conical roller. In some embodiments, at least one of the one or more reservoirs is pre-loaded with a fluid. In some embodiments, the system further comprises at least one valve formed in the flexible layer, each valve preventing flow of fluid from a pre-loaded reservoir until the fluid is forced from the reservoir by action of the movable compression device. In some embodiments, at least one of the one or more reservoirs is pre-loaded with a diluent. In some embodiments, at least one of the one or more reservoirs is pre-loaded with a reagent. In some embodiments, at least one of the one or more reservoirs is pre-loaded with an antibody. In some embodiments, the substantially rigid layer defines a sample loading port for loading a sample of an analyte into the composite wafer. In some embodiments, the substantially rigid layer defines at least one fluid channel. In some embodiments, the composite wafer further comprises a sampling medium to which fluid is delivered from one of the fluid flow channels. In some embodiments, a first one of the reservoirs is pre-loaded with a diluent; the substantially rigid layer defines a sample loading port connected by one of the fluid flow channels downstream of the first reservoir for loading a sample of an analyte into the composite wafer; and a second one of the reservoirs is connected by one of the fluid flow channels downstream of the sample loading port, such that upon actuation of the movable compression device, diluent is forced from the first reservoir, and carries the analyte to the second reservoir in a test fluid. In some embodiments, the system further comprises a sampling medium, wherein the test fluid is delivered from the second reservoir to the sampling medium via one of the fluid flow channels. In some embodiments, one or two additional reservoirs are disposed between the second reservoir and the sampling medium. In some embodiments, a third reservoir is pre-loaded with a washing fluid, and the substantially rigid layer defines a fluid flow layer that delivers the washing fluid to the sampling medium. In some embodiments, the third reservoir is positioned such that the advancement of the movable compression device forces the buffer from the third reservoir after the test fluid has reached the sampling medium. In some embodiments, the analyte is blood, and the system is configured to perform process steps in the measurement of HbA1c in the blood. The movable compression device may be configured to be manually actuated. The movable compression device and the composite wafer may undergo rotary relative motion. The movable compression device and the composite wafer may undergo linear relative motion. In some embodiments, the system further comprises a protective holder that substantially encloses the flexible layer, the protective holder defining an opening providing access to the flexible layer by the movable compression device.
According to another aspect, a fluid manipulation device comprises a flexible layer having one or more recesses in one face. The one or more recesses define one or more reservoirs and one or more fluid channels among the one or more reservoirs. The system further includes a substantially rigid layer adhered to a face of the flexible layer such that the substantially rigid layer forms a closing side of the one or more recesses, and an analysis area. The reservoirs, fluid channels, and analysis area are arranged such that a test fluid is moved through reservoirs, fluid channels, and analysis area in a prescribed order by progressive application of a movable compression device to the flexible layer. At least one reservoir may be pre-loaded with a fluid. In some embodiments, the substantially rigid layer defines at least one fluid flow channel. In some embodiments, the fluid flow channel defined in the substantially rigid layer permits flow of fluid counter to the direction of progression of the movable compression device.
According to another aspect, a method comprises providing a composite wafer having a flexible layer and a substantially rigid layer adhered to the flexible layer. The flexible layer defines one or more recesses that are covered by the substantially rigid layer to form one or more reservoirs and one or more fluid channels among the one or more reservoirs. The method further includes contacting a movable compression device with the flexible layer, and progressively compressing the flexible layer such that when the movable compression device traverses the flexible layer, fluid is forced through the one or more fluid channels and the one or more reservoirs in a sequence determined by the layout of the one or more fluid channels and the one or more reservoirs. In some embodiments, the method further comprises stopping and restarting the progressive compression. In some embodiments, the progressive compression proceeds in a primary direction, and the method further comprises disengaging the movable compression device from the flexible layer; moving the movable compression device or the composite wafer or both to reposition the movable compression device with respect to the composite wafer; re-engaging the movable compression device with the flexible layer; and causing relative motion between the movable compression device and the composite wafer in a direction opposite the primary direction.
Composite wafer 101 further comprises a flexible layer 103 and a substantially rigid layer 104. Flexible layer 103 may be made of a soft, readily-compressible polymer such as molded silicone rubber, polyester, or another suitable material or blend of materials. Substantially rigid layer 104 may be made of a substantially rigid plastic material such as polyester, polycarbonate, acrylonitrile butadiene styrene (ABS), acrylic, or another suitable material or a blend of materials.
Composite wafer 101 may be of any suitable size, but in some embodiments may be between about 10 and 50 mm wide and about 25-300 mm long. In one example embodiment, composite wafer 101 is 25.4×95.25 mm (1.0×3.75 inches). The flexible and substantially rigid layers may be any workable thickness, but in some embodiments may be between about 1 and 10 millimeters thick. In one example embodiment, flexible layer 103 is about 1.524 mm (0.06 inches) thick, and substantially rigid layer 104 is about 1.778 mm (0.07 inches) thick. It will be recognized that the size of the composite wafer may be selected in accordance with its intended use and the number of internal features required.
Referring again to
Once substantially rigid layer 104 is adhered to flexible layer 103, substantially rigid layer forms a side of reservoirs 203-205 and fluid flow channels 202, so that the reservoirs and fluid flow channels are closed, other than their inlets and outlets within composite wafer 101.
During operation of composite wafer 101, roller 102 is advanced in the direction shown in
In an example embodiment, reservoir 201 may be pre-loaded with a diluent to be used in testing blood for the level of HbA1c. A valve 207 prevents leakage of the diluent from reservoir 201 during shipping and storage, but permits the diluent to flow into fluid flow channel 202 under the impetus of roller 102.
Referring again to
Also provided in substantially rigid layer 104 is an analyte loading port 209. Analyte loading port 209 may be, for example a funnel-shaped opening through substantially rigid layer 104 and aligned with fluid flow channel 202. In the HbA1c testing example, a sample of a patient's blood may be supplied through analyte loading port 209, and may partially fill fluid flow channel 202 by capillary action. In some embodiments, a vent 210 may be provided through substantially rigid layer 104, aligned with a location on fluid flow channel 202 downstream from analyte loading port 209. The relationship of analyte loading port 209 and vent 210 to fluid flow channel 202 is also visible in
In some embodiments, any analyte loading port such as analyte loading port 209 may be covered after the sample is loaded, for example with an adhesive sticker or other cover, to prevent the sample from being forced back out of composite wafer 101 during travel of roller 102. Similarly, any vents such as vent 210 may be covered.
Once the analyte, for example blood, is loaded through analyte loading port 209, roller 102 may be advanced to force the diluent into fluid flow channel 202, carrying the blood sample with it to reservoir 203. Reservoirs 203-205 may be used in other steps of the test being performed. For example, the sample may be kept in reservoir 203 for a period of time for a digestion step. The digestion may be facilitated by a reagent pre-loaded in reservoir 203 or present in the diluent that was pre-loaded in reservoir 201. The progress of roller 102 may be stopped once the sample is transferred into reservoir 203 in order to allow time for the digestion step to occur.
Roller 102 may then be advanced again, to force the sample into reservoirs 204 and 205 in turn. For example, reservoir 204 may contain a buffer that stops the digestion reaction, and reservoir 205 may be pre-loaded with antibodies selected to bind with glucose that may have attached to the hemoglobin in red blood cells in the blood sample being tested. For example, the antibodies may have been pre-loaded in reservoir 205 in a lyophilized form, or may be suspended in a fluid pre-loaded in reservoir 205. Multiple kinds of antibodies may be provided. The antibodies may be tagged with one or more fluorophores, to facilitate their detection later in the test as is explained below. Different antibodies may be tagged with different fluorophores. Additional reservoirs could be included, and could hold additional antibodies. If desired, additional loading ports similar to loading port 208 may be provided for reservoirs other than reservoir 201, and additional valves similar to valve 207 may be provided at other places in the fluid path in composite wafer 101, for example to isolate and contain fluids in other pre-loaded reservoirs for shipping and storage.
As with the digestion step, the advancement of roller 102 may be stopped and re-started as needed to allow time for reactions to occur at the various stages in the test being conducted.
In some embodiments, roller 102 may be utilized for enhancing mixing of components of the sample under test. For example, in the embodiment of
Roller 102 may be further actuated to force the fluid under test to analysis area 206. Analysis area 206 may include, for example, an absorbent medium impregnated with proteins to which the antibodies from reservoirs 204 and 205 may attach. The absorbent medium may comprise nitrocellulose or another kind of absorbent medium. The test fluid may transport across the absorbent medium by capillary wicking action. Different areas of the absorbent medium may be impregnated with different proteins to which different antibodies may attach.
Composite wafer 101 may also include a washing fluid reservoir 211, also formed in flexible layer 103 and covered by substantially rigid layer 104. Washing fluid reservoir 211 may be pre-loaded with a washing fluid via loading port 212, similar to port 208, and a valve 213 similar to valve 207 may be provided to retain the washing fluid in washing fluid reservoir 211 during shipping and storage of composite wafer 101.
Washing fluid reservoir 211 may be connected with analysis area 206 by a flow channel 302 formed in substantially rigid layer 104 and visible in
The positioning of washing fluid reservoir 211 and the volume of flow channel 302 are such that the washing fluid forced from washing fluid reservoir 211 by the advancement or roller 102 arrives at analysis area 206 after all or substantially all of the test fluid has already contacted analysis area 206. The washing fluid may serve to carry away antibodies not bound to any of the proteins present in analysis area 206, removing stray antibodies that could otherwise interfere with interpretation of the test result. The washing fluid and other fluid components it carries may be exhausted into a collection area within a testing machine (not shown) performing the test, or into an additional collection reservoir (not shown) within composite wafer 101.
The example flow channel 302 in substantially rigid layer 104 permits flow of the washing fluid in the reverse direction to the motion of roller 102. It will be appreciated that reversals of direction of the flow within flexible layer 103 (flow counter to the direction of the travel of roller 102) may be difficult or impossible to achieve.
To read the result of the test, analysis area 206 may be illuminated in order to stimulate fluorescence of the fluorphores tagged to the antibodies adhering to the various areas of analysis area 206. The wavelengths and intensity of light emanating from analysis area 206 may be measured and interpreted to provide a test result.
It will be recognized that many, many variations from this example are possible within the scope of the appended claims. The number, size, and arrangement of reservoirs present in a particular composite wafer may be varied according to the intended use of the composite wafer. Valves, loading ports, analyte loading ports, and other features may be provided as needed, in any workable arrangement. Flow channels may split into parallel pathways, may rejoin, or may form any workable network of channels. Different kinds of analysis areas may be provided.
A composite wafer and actuator according to embodiments may be used for performing any workable medical test, for example DNA identification, or for other purposes. For example, reservoirs may be separately loaded with two parts of a two-part adhesive, and the two parts may be mixed and dispensed from the composite wafer by actions of the roller or other movable compression device.
Also shown in
In other embodiments, other kinds of movable compression devices may be used. For example, a set of solenoid-driven plungers may be aligned with the reservoirs in the flexible layer, and may compress the reservoirs in turn under the control of a controller. In another example, actuators made of a memory metal such as nitinol may be placed under the reservoirs, and may be caused to compress individual reservoirs by selective heating of the nitinol actuators. Many other kinds of movable compression devices may be envisioned.
In some embodiments, a rotary system may be utilized in place of the linear motion of a roller such as roller 511.
Fluid manipulation device 700 is a rotary analogue of example fluid manipulation device 100, and includes components similar to the components of fluid manipulation device 100, but in a rotary arrangement. For example, composite wafer 701 includes a flexible layer 703 and a substantially rigid layer 704. Reservoirs 705-709 may hold diluents, reagents, washing fluid, or other materials, depending on the intended use of fluid manipulation device 700. Loading ports such as ports 710 and 711 may be provided for pre-loading reservoirs as needed. An analyte loading port 712 and vent 713 may be provided for loading a predetermined quantity of an analyte into the system. Valves such as valves 714 and 715 may be provided to retain fluids pre-loaded into composite wafer 701 during shipping, handling, and storage. An analysis area 716 may include, for example, a nitrocellulose strip as discussed above, and may receive washing fluid from washing fluid reservoir 709 after the test fluid, by virtue of reverse channel 717 formed in substantially rigid layer 704. Opening 718 may accommodate a keyed shaft (not shown) for rotating composite wafer 701, or for preventing its rotation. Other mechanisms for creating relative motion between composite wafer 701 and roller 702 may be envisioned.
Because a composite wafer according to embodiments of the invention does not require any external pressure source, embodiments of the invention may be especially amenable to use in remote locations where electric power or other utilities may be limited, unavailable, or unreliable.
Preferably for field use, analysis area 1003 is constructed to present the test results using visible light. Alternatively, upon completion of the movement of roller 102, analysis area 1003 may be illuminated using a battery-powered portable light source, and then photographed (possibly through an appropriate filter) to make a record of the test. The photograph may be transmitted, for example by cellular telephone, to a remote location for interpretation of the test results.
In the claims appended hereto, the term “a” or “an” is intended to mean “one or more.” The term “comprise” and variations thereof such as “comprises” and “ comprising,” when preceding the recitation of a step or an element, are intended to mean that the addition of further steps or elements is optional and not excluded.
It is to be understood that any workable combination of the elements and features disclosed herein is also considered to be disclosed.
The invention has now been described in detail for the purposes of clarity and understanding. However, those skilled in the art will appreciate that certain changes and modifications may be practiced within the scope of the appended claims.
