Mechanical microfluidic manipulation methods and apparatuses

Abstract

Disclosed are devices and methods for robust mechanical manipulation of microfluidic droplets within an air gap formed between hydrophobic sheets of a cartridge. A mechanical force applicator locally reduces the gap to draw and translate droplets. Performance is enhanced by adding non‑ionic surfactants, preferably secondary alcohol ethoxylates (e.g., TERGITOL), to set the droplet contact angle to between about 38 and 42 degrees, enabling smooth mobility while reducing fouling. The apparatus may be configured to provide conforming surfaces for the cartridge at the and inlet wells to enhance loading, processing, heating, and retrieval. The methods are compatible with biological samples (e.g., DNA) and can improve sequencing workflows.

Description

MECHANICAL MICROFLUIDIC MANIPULATION METHODS AND APPARATUSESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority to U.S. provisional patent application 63 / 738,479, titled “MICROFLUIDIC MANIPULATION DEVICES AND METHODS,” and filed on 12 / 23 / 2024; this patent application also claims priority to U.S. provisional patent application no. 63 / 738,490, titled “DROPLET HANDLING WITH MECHANICAL MICROFLUIDIC MANIPULATION,” filed on 12 / 23 / 2024, each of which is herein incorporated by reference in its entirety.INCORPORATION BY REFERENCE

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.FIELD

[0003] The disclosure relates to microfluidic devices and associated fluid manipulation and systems, and methods of using them.BACKGROUND

[0004] Microfluidic systems are used to manipulate and process very small volumes of fluid for use in chemical, biological, and medical applications. Microfluidics generally provides straightforward control over multiple reagents (no pumps, valves, or tubing required), facile handling of both solids and liquids (no channels to clog), and compatibility with even troublesome reagents (e.g., organic solvents, corrosive chemicals) because hydrophobic surfaces (typically Teflon-coated) in contact with the droplets of fluid are chemically inert. Some microfluidic devices use relatively large electric fields selectively applied to an array of electrodes to manipulate the droplets. Other microfluidic devices use mechanical mechanisms to manipulate droplets using directed capillary action. Such mechanical microfluidic systems may move droplets through an application of force that reduces a gap between generally hydrophobic sheets where a droplet has been placed. However, it may be challenging to manipulate droplets mechanically reliably without the use of a coating (e.g., a hydrophobic coating, such as a “dropgloss” shell of liquid wax or oil).

[0005] It would be particularly useful to provide methods, compositions and apparatuses forimproving mechanical microfluidic systems.SUMMARY OF THE DISCLOSURE

[0006] In general, described herein are methods and apparatuses (e.g., devices, systems, and the like) for preparing, manipulating and / or analyzing a sample droplets, such as microfluidic droplets. In particular described herein are methods, compositions and apparatuses for mechanical microfluidic droplet manipulation having robust and improved properties.Microfluidic droplets can include any feasible biologic liquid, including liquid that includes one or more DNA molecules. For example, described herein are a plurality of microfluidic apparatus (e.g., devices and methods) that may be especially helpful for handling and analyzing a clinical, laboratory, biological, or chemical sample.

[0007] The example methods described herein may include the use of a surfactant with the liquid prior to manipulation with a microfluidic apparatus. In some examples, the surfactant may be a non-ionic surfactant, such as TERGITOL, TWEEN, and / or PLURONIC surfactants.TERGITOL refers to secondary alcohol ethoxylates, a type of nonionic surfactant made from ethoxylated secondary alcohols. TWEEN refers to Polysorbate. PLURONIC refers to a triblock copolymer made of polyethylene oxide) (PEO) and polypropylene oxide) (PPO) (and may also be referred to as a Poloxamer). The surfactants may advantageously reduce surface fouling, improve droplet mobility, and / or reduce or eliminate evaporation. In many cases, the surfactant may not affect any post processing (processing after the addition of the surfactant).

[0008] The microfluidic apparatuses may include those that manipulate droplets through the application of voltages to electrodes as well as apparatuses that can manipulate the droplets through a mechanical actuator that provides a pressure to reduce a gap next to the droplet, thereby drawing the droplet toward the actuator.

[0009] The surfactants may be added in any feasible amount with respect to the biologic liquid volume. In some examples, the surfactant may be added in a range of between 0.0005% to 3.0% w / v (percent weight / percent volume).

[0010] The example methods described herein may also mix a surfactant with a biologic liquid to improve deoxyribonucleic acid (DNA) sequencing. In some cases, the surfactant may improve the performance of a DNA sequencer such that longer DNA molecule segments may be sequenced, in some cases by a pore-based DNA sequencer.

[0011] Some examples described herein include a method for performing microfluidic manipulation of a biologic liquid. The method also includes receiving or obtaining a biologic liquid, adding a surfactant to the biologic liquid, introducing a droplet of a mixture of the biologic liquid and the surfactant to a microfluidic manipulation device, manipulating, by themicrofluidic manipulation device, the droplet within a region of the microfluidic manipulation device, and removing the droplet from the microfluidic manipulation device.

[0012] The method of introducing the droplet to the microfluidic manipulation device may include introducing, at a first location in a cartridge, the droplet, where the cartridge includes a first sheet and a second sheet separated by a predetermined distance from the first sheet so as to form a gap between the first sheet and the second sheet. In some examples, manipulating the droplet can include reducing the gap in the cartridge by a predetermined amount adjacent to the droplet.

[0013] Any of the methods described herein may include affixing the cartridge to a base prior to introducing the droplet into the cartridge. In some examples, the first sheet and the second sheet of the cartridge are hydrophobic. In some other examples, surfaces of the first sheet and the second sheet disposed toward the gap are treated with a hydrophobic coating.

[0014] In any of the methods described herein, manipulating the droplet may include applying a voltage to a subset of electrodes disposed under the cartridge so as to move the droplet through electro wetting. In some examples, a subset of electrodes are disposed in a base unit disposed under the cartridge.

[0015] Any of the methods described herein may include surrounding the droplet with the surfactant prior to introducing the droplet into the cartridge. In some implementations, the methods described herein may include surrounding the droplet with an evaporation reducing reagent prior to introducing the droplet into the cartridge. The surfactant may be a non-ionic surfactant. One example surfactants that are particularly effective are nonionic surfactant made from ethoxylated secondary alcohols such as Terigtol ™. In particular and surprisingly, nonionic surfactant made from ethoxylated secondary alcohols surfactants were useful without the need of an evaporation reducing reagent (e.g., “dropgloss”) such as a hydrophobic (e.g., wax, oil, etc.) material. In particular, the surfactant (such as nonionic surfactant made from ethoxylated secondary alcohols) were used in a concentration such that the surface angle of the droplet within the air gap was modified by the surfactant to have a contact angle of between about 30-50 degrees (e.g., more preferably between about 35-45 degrees, even more preferably between about 38-42 degrees, between about 39-41 degrees, about 38 degrees, about 39 degrees, about 40 degrees, about 41 degrees, about 42 degrees, etc.). Although other detergents may reduce the surface angle within the air gap to approximately this range (e.g., between about 38-42 degrees, etc.) only nonionic surfactant made from ethoxylated secondary alcohols were found to consistently achieve this range over a large concentration range (e.g., between about 0.01% and 5%), and in particular at higher percentages (e.g., between greater than 1.1% and 6% or more, between 1.5% and 5%, between 2% and 5%, between 3% and 6%, etc.) w / v. Note that anaqueous droplet on a hydrophobic surface without a surfactant as described herein (e.g., a nonionic surfactant such as TURGITOL), the surface angle is typically between 90-120 degrees).

[0016] In any of the methods described herein, the surfactant may be added in an amount of about 0.05% w / v (percent weight / percent volume) with respect to the biologic liquid. In some examples, the surfactant may be added in a range of between 0.0005% to 5.0% w / v with respect to the biologic liquid. The amount of surfactant may be adjusted within this range to provide a contact angle of between about 35-45 degrees, and in particular, between about 38-43 degrees (e.g., about 40 degrees, such as between 38-42 degrees, or between 39-41 degrees). As mentioned, nonionic surfactant made from ethoxylated secondary alcohols were of particular use, as they may result in a contact angle of about 40 degrees over a range of about 0.5 to 6% w / v, and are particularly consistent at higher concentrations, such as about l%-6% (e.g., greater than 1% to 6% or more).

[0017] Examples described in this disclosure may be implemented as a microfluidic manipulation device. A microfluidic manipulation device may be configured to: receive or obtain a biologic liquid, receive or obtain a surfactant, mix together the biologic liquid and the surfactant, introduce a droplet of a mixture of the biologic liquid and the surfactant to a first region of the microfluidic manipulation device, and manipulate the droplet to a second region of the microfluidic manipulation device.

[0018] A method may include receiving or obtaining a biologic liquid that includes at least one deoxyribonucleic acid (DNA) molecule, adding a surfactant to the biologic liquid, and sequencing a droplet of a mixture of the biologic liquid and the surfactant to determine at least a partial nucleotide sequence of the one at least one DNA molecule.

[0019] In any of the methods described herein, sequencing the droplet may include sequencing with a pore-based DNA sequencer. In any of the methods described herein, the surfactant can be a non-ionic surfactant, such as but not limited to TERGITOL, TWEEN, and / or PLURONIC surfactants.

[0020] In any of the methods described herein, the surfactant may be added in an amount of about 0.05% w / v (percent weight / percent volume) with respect to the biologic liquid. In some examples, the surfactant is added in a range of between 0.0005% to 6.0% w / v with respect to the biologic liquid. In particular the surfactant may preferably be a nonionic surfactant made from ethoxylated secondary alcohols (e.g., TERGITOL) and may be between about 1% and 6% w / v (e.g. between about l%-3%, etc.).

[0021] Described herein are methods of performing microfluidic manipulation of a droplet that include: introducing the droplet into an air gap formed between a first sheet that is elastically deformable and a second sheet, wherein the droplet comprises a nonionic surfactant at aconcentration such that a contact angle of the droplet within the air gap is between 38 degrees and 42 degrees on a hydrophobic surface of the first sheet, the second sheet or the first and second sheets; applying a compression force against the first and / or second sheet using a mechanical force applicator to form a region of locally reduced gap width within the air gap that is adjacent to droplet, thereby drawing the droplet towards the region of locally reduced air gap; and moving the droplet within the air gap by translating the mechanical force applicator along an outer surface of the first sheet to translate the region of locally reduced gap width within the air gap so that the droplet follows the mechanical force applicator.

[0022] In any of these methods, the surfactant may be a nonionic surfactant made from ethoxylated secondary alcohol, such as TERGITOL.

[0023] For example, described herein are methods for performing microfluidic manipulation of a droplet, the method comprising: introducing the droplet into an air gap formed between a first sheet that is elastically deformable and a second sheet, wherein the droplet comprises a nonionic surfactant made from ethoxylated secondary alcohol so that a contact angle of the droplet within the air gap is between 38 degrees and 42 degrees; applying a compression force against the first sheet using a mechanical force applicator to form a region of locally reduced gap width within the air gap that is adjacent to droplet, thereby drawing the droplet towards the region of locally reduced air gap; and moving the droplet within the air gap by translating the mechanical force applicator along an outer surface of the first sheet to translate the region of locally reduced gap width within the air gap so that the droplet follows the mechanical force applicator.

[0024] The first sheet, the second sheet, and / or the first and second sheets may have a hydrophobic surface (e.g., the surfaces forming the air gap in which the droplet resides) that are configured to contact the droplet. The droplet may sit on either the first or second sheets. Either the first sheet the second sheet or both may be manipulated to compress the air gap and move the droplet. For example, the surfaces of the first sheet and the second sheet that are disposed toward the gap are treated with a hydrophobic coating.

[0025] The liquid droplet may be any appropriate liquid, particularly aqueous liquid droplets. In any of these examples the droplet may comprise a biologic liquid. Any of these methods may include acquiring the droplet.

[0026] The concentration of the nonionic surfactant may be, e.g., between about 1% and 6% (e.g., between 1.1% and 6%, etc.).

[0027] In general, any of these methods may include removing the droplet from the microfluidic manipulation device. Removal may be particularly simplified because the droplet may be uncoated; e.g., the droplet does not include a hydrophobic shell. Previously, it wasbelieved that an aqueous droplet would benefit from the use of a dropgloss (e.g. a hydrophobic shell material, such as a liquid wax or oil). As described herein, these methods and apparatuses may be optimally used without such a material.

[0028] In general, any of these methods may include introducing the droplet to the microfluidic manipulation device at a first location in a cartridge that includes the first sheet and the second sheet separated by a predetermined distance to form the gap therebetween.Introducing may be performed by a pipette, either manually or automatically.

[0029] Applying the compression force may generally comprise reducing the air gap by a predetermined amount adjacent to the droplet. In some cases the method may include affixing a cartridge that includes the first sheet and the second sheet to a base prior to introducing the droplet into the cartridge.

[0030] Any of these methods may include adding the nonionic surfactant to the droplet before the droplet is introduced into the air gap. In some cases the nonionic surfactant may be added to the droplet while the droplet is within the air gap.

[0031] Also described herein are methods and apparatuses (e.g., devices, systems, and the like) for preparing, manipulating and / or analyzing a sample droplets, such as microfluidic droplets. For example, described herein are a plurality of microfluidic apparatus (e.g., devices and methods) that may be especially helpful for handling and analyzing a clinical, laboratory, biological, or chemical sample.

[0032] The apparatus may include two parallel hydrophobic sheets spaced apart by a gap of a predetermined distance. The microfluidic droplet may be manipulated (e.g., moved, controlled, separated, mixed, and the like) by selectively reducing the gap, particularly near the microfluidic droplet. In some examples, the gap may be reduced applying a force (e.g., a compressive force) to one or more of the parallel sheets.

[0033] Examples described in this disclosure may be implemented as a microfluidic device. The microfluidic device may include a cartridge that, in turn, includes a first sheet comprising a first surface and a second surface, wherein the first surface of the first sheet is hydrophobic, a second sheet comprising a first surface and a second surface, wherein the first surface of the second sheet is hydrophobic and the first surface of the first sheet is disposed toward and separated from the first surface of the second sheet by a predetermined distance to form a gap between the first sheet and the second sheet, and at least one input port on the first sheet configured to introduce a first microfluidic droplet into the gap. The microfluidic device may also include a controller configured to selectively reduce the predetermined distance in one or more regions within the gap adjacent to the first microfluidic droplet, wherein the reduced predetermined distance moves the first microfluidic droplet within the cartridge.

[0034] Examples described herein include a base unit that may be coupled to the cartridge. The base unit may include one or more features that can shape one of the sheets of the cartridge. The feature may collect a droplet as the droplet is introduced into the cartridge.

[0035] For example, described herein are microfluidic apparatuses that includes a cartridge. The cartridge may include a first sheet; a second sheet, where the first sheet is separated from the second sheet by a predetermined distance to form a gap between the first sheet and the second sheet; and at least one inlet on the first sheet configured to receive a first microfluidic droplet into the gap. The microfluidic apparatuses also includes a base unit configured to receive the cartridge. The base unit may include at least one inlet well positioned under the inlet when the cartridge is coupled to the base unit, and one or more vacuum ports configured to apply a vacuum the second sheet and cause the second sheet to conform at least to a shape of the at least one inlet well.

[0036] In any of the microfluidic apparatuses described herein, the input well is configured to capture a predetermined volume of liquid may include the microfluidic droplet. In some examples, the vacuum at least partially conforms the second sheet to the inlet well. In some examples, the inlet well may have an elongate oval shape. In some other examples, the inlet well may have a tear drop shape.

[0037] Any of the microfluidic apparatuses described herein may include a hold down configured to fit over and position the cartridge with respect to the base unit. In some examples, hold down includes one or more grooves to receive an actuator to selectively reduce the predetermined distance in the gap of the cartridge.

[0038] Any of the microfluidic apparatuses described herein may include an actuator configured to reduce the predetermined distance between the first sheet and the second sheet. In some examples, the actuator is further configured to move the microfluidic droplet from a region near the inlet to other regions between the first sheet and the second sheet.

[0039] Any of the microfluidic apparatuses described herein may include a controller configured to actuate and move the actuator. Any of the microfluidic apparatuses described herein may include a vacuum pump configured to supply the vacuum to the base. The controller may be configured to control the vacuum pump. In some examples, the microfluidic apparatus may include a heater within the base unit.

[0040] In any of the microfluidic apparatuses described herein, the first sheet and the second sheet of the cartridge are hydrophobic. In some examples, a first surface of the first sheet and a first surface of the second sheet are disposed toward the gap and are treated with a hydrophobic coating.

[0041] In some examples, the second sheet of the cartridge is disposed against the base unit. In some cases, applying the vacuum causes the second sheet to be drawn into an inlet well positioned beneath the inlet, the inlet well forming a convex surface with respect to the conforming surface. In some examples, a surfactant is added to the microfluidic droplet.

[0042] In any of the microfluidic apparatuses described herein, selectively reducing the gap moves the microfluidic droplet to a region of the base unit adjacent to a heating unit. In some examples, the inlet well guides the microfluidic droplet to a predetermined region as the microfluidic droplet is introduced into the gap. In some other examples, the inlet well guides the microfluidic droplet to a droplet removal region in the cartridge.

[0043] Any of the methods described herein may include attaching a cartridge onto a base unit, where the cartridge includes a first sheet, a second sheet, and a gap therebetween, and the base unit includes a conforming surface configured to receive the cartridge. The method further includes applying a vacuum through the conforming surface causing the second sheet to conform to a shape of the conforming surface, introducing a microfluidic droplet though an inlet of the cartridge and into the gap of the cartridge, and selectively reducing, by an actuator, the gap in one or more regions adjacent to the microfluidic droplet so as to move the microfluidic droplet.

[0044] In any of the methods described herein, applying the vacuum causes the second sheet to be drawn into an inlet well positioned beneath the inlet, the inlet well forming a convex surface with respect to the conforming surface. In some examples, the inlet well guides the microfluidic droplet to a droplet removal region in the cartridge.

[0045] In any of the methods described herein, introducing the microfluidic droplet includes adding a surfactant to the microfluidic droplet. In any of the methods described herein, selectively reducing the gap moves the microfluidic droplet to a region of the base unit adjacent to a heating unit.

[0046] A non-transitory computer readable storage medium comprising instructions that when executed by one or more processors of a device, cause the device to perform operations that includes attaching a cartridge onto a base unit, where the cartridge includes a first sheet, a second sheet, and a gap therebetween; and the base unit includes a conforming surface configured to receive the cartridge. The method also includes applying a vacuum through the conforming surface causing the second sheet to conform to a shape of the conforming surface, introducing a microfluidic droplet though an inlet of the cartridge and into the gap of the cartridge; and selectively reducing, by an actuator, the gap in one or more regions adjacent to the microfluidic droplet so as to move the microfluidic droplet.BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0048] FIGS. 1A-1C show a portion of a microfluidic device.

[0049] FIG. ID shows a top view of another exemplary microfluidic device.

[0050] FIG. 2 shows block diagram illustrating example microfluidic processing.

[0051] FIG. 3 shows an example microfluidic manipulation device.

[0052] FIG. 4 is a flowchart showing an example method for manipulating a liquid with a microfluidic device.

[0053] FIG. 5A shows an example cartridge for use with a microfluidic manipulation device.

[0054] FIG. 5B is a schematic drawing showing an example droplet flow for a cartridge.

[0055] FIG. 6 shows a partial view of an example microfluidic manipulation device.

[0056] FIG. 7 shows simplified view a cartridge during different stages of processing within a microfluidic manipulation device.

[0057] FIG. 8 shows test data graphs regarding read length of DNA molecule segments.

[0058] FIG. 9 is a flowchart showing an example method for sequencing a DNA sample.

[0059] FIG. 10 shows test data graphs regarding read length of DNA molecule segments using pore-based DNA sequencers.

[0060] FIG. 11 shows pore occupancy data for a DNA elution with and without using a nonionic surfactant.

[0061] FIG. 12 is an exploded view of an example microfluidic system.

[0062] FIG. 13 shows a partial view of an example microfluidic system.

[0063] FIG. 14A shows a partial view of an example conforming surface.

[0064] FIG. 14B shows another partial view of the conforming surface of FIG. 14A.

[0065] FIG. 15 shows an example actuator assembly.

[0066] FIG. 16 is a flowchart showing an example operation for manipulating a microfluidic droplet.

[0067] FIG. 17 shows a block diagram of a device that may be an example of any microfluidic device or system described herein.DETAILED DESCRIPTION

[0068] One example of a micro fluidic apparatus (e.g., device, system or the like) for controlled liquid manipulation may include a two-dimensional (planar) fluidic chamber or cartridge. The chamber may include a first sheet and a second sheet separated by a gap therebetween. The gap may separate the first and second sheets by any feasible distance. The first and second sheets may be hydrophobic or may include hydrophobic coatings. At least one of the first and second sheets may be flexible and / or deformable.

[0069] Microfluidic droplets may be manipulated through mechanical manipulation that applies forces directly or indirectly to the first sheet or second sheet selectively reducing the gap. This process may sometimes be referred to as mechanical actuation on the surface (MAOS). MAOS systems are described in U.S. patent application Ser. No. 18 / 062,007, filed December 5, 2022, now U.S. Pat. No. 11,857,961; and Ser. No. 18 / 062,011, filed December 5, 2022, now U.S. Pat. No. 11,772,093, all commonly assigned, the disclosures of which are incorporated by reference herein in their entireties. The applied forces, which may include compressive forces, may be applied near or adjacent to droplets within the gap. In some aspects, reducing the gap may cause the droplets to move, separate, combine, mix, incubate, or the like.

[0070] In some examples, the forces may be applied by a stylus or wheel. The stylus may include an electrode and / or a controllable magnet. The microfluidic droplets may be manipulated with a combination of pressure, exerted by the stylus, in conjunction with a voltage provided by the electrode and / or a magnetic field provided by the magnet.

[0071] Some MAOS implementations rely on the encapsulation of aqueous solutions within an oil shell droplet, which acts as the driving force for fluid manipulation. This oil encapsulation offers several benefits, including the prevention of surface fouling on MAOS cartridges and minimizing evaporation during high-temperature processes. However, the addition of oil presents notable challenges. It often leads to uncontrolled wetting and can adversely impact downstream sample preparation and analysis in biological processes. These issues stem primarily from the oil's interaction with reagents, which can hinder specific steps in the MAOS process.

[0072] Another example of a microfluidic apparatus can include the fluidic chamber or cartridge described above and a base that is configured to receive or come into contact with the chamber or cartridge. The base may include an array of electrodes. When the cartridge is affixed to the base, and a liquid droplet is introduced into the cartridge, the droplet within the cartridge may be moved by selectively providing a high voltage to a subset of the array of electrodes. This processes is referred to as electro wetting.

[0073] Oil encapsulation can also be used microfluidic apparatuses that use electrowetting to manipulate droplet. For example, the oil can prevent or reduce surface fouling and prevent orreduce evaporation. However, oil encapsulation can still react with reagents and induce uncontrolled wetting.

[0074] Described herein are methods and compositions in which the MAOS technique may achieve all of the advantages of the use of a dropgloss (e.g., a hydrophobic shell, such as an oil or wax coating), including moving the droplet smoothly and predictably within the air gap by adding a surfactant, and in particular a nonionic surfactant made from ethoxylated secondary alcohol (e.g., TURGITOL, SOFT ANOL, BIO-SOFT N-Series) so that a contact angle between the droplet and a surface of the air gap is about 40 degrees (e.g., between about 38 degrees and 42 degrees, between about 35 degrees and 45 degrees, etc.). Repeated experiments have shown that using a nonionic surfactant made from ethoxylated secondary alcohol so that the contact angle is about 40 degrees result in reliable and robust movement of the droplet within the air gap without the need for any dropgloss. Thus any of these methods and apparatuses may include exclude the use of dropgloss (e.g., a hydrophobic shell material) when using a nonionic surfactant made from ethoxylated secondary alcohol, as described herein (e.g., so that the surface tension is sufficiently and reliably lowered such that the contact angle is about 40 degrees (e.g., between about 38-42 degrees, etc.).

[0075] FIG. 1A shows a portion of a microfluidic device 100. Any of the devices described herein may be implemented in part or in whole as a system or any other feasible apparatus. The microfluidic device 100 may include a first sheet 110 and a second sheet 120 separated by a gap 130. In some examples, the gap 130 may generally be filled with air. In some examples, the microfluidic device 100 may be a cartridge that may be selectively coupled to a control unit or base station. As shown, the first sheet 110 may be a “top” sheet and the second sheet 120 may be a “bottom” sheet. That is, the first sheet 110 may be higher or “above” the second sheet 120. The second sheet 120 may be closer to the ground than the first sheet 110. In other examples, the second sheet 120 may be above the first sheet 110.

[0076] The first sheet 110 and the second sheet 120 may form a planar structure that occupies any feasible area. The first sheet 110 and the second sheet 120 are shown in an initial position. In the initial position, the first sheet 110 and the second sheet 120 are relatively parallel to each other separated by a distance associated with and / or determined by the gap 130.

[0077] Each sheet may include two surfaces. For example, the first sheet 110 may include a first surface 111 and a second surface 112 and the second sheet 120 may include a first surface 121 and a second surface 122. For ease of description, the first surfaces 111 and 121 may be disposed toward the gap 130, while the second surfaces 112 and 122 may be disposed on opposite sides of the first sheet 110 and the second sheet 120, respectively. In other words, the second surfaces 121 and 122 may be disposed away from the gap 130.

[0078] The first surfaces 111 and 121 may be hydrophobic (water repelling). In some examples, the first and second sheets 110 and 120 (and thus the first surfaces 111 and 121) may be formed from a hydrophobic material. In some other examples, the first surfaces 111 and 121 may be a hydrophobic coating or layer applied upon the first and second sheets 110 and 120, respectively.

[0079] A droplet 140 may be introduced into the gap 130. In some cases, the droplet 140 may be introduced in the gap 130 through a port or opening (not shown) on the first sheet 110 and / or the second sheet 120. The droplet 140 may be mechanically manipulated by selectively reducing the gap near the droplet 140. In some examples, one or more of the sheets 110 and 120 may be flexible. Flexible sheets may deflect in response to one or more forces. For example, the first sheet 110 may be flexible and the second sheet 120 may be rigid or semi-rigid. Rigid or semi-rigid sheets may resist deflection in response to one or more forces. In other examples, the second sheet 120 may be flexible and the first sheet 110 may be rigid or semi-rigid. In still other examples, both the first sheet 110 and the second sheet 120 may be flexible. As used herein, the term flexible may describe any material that may flex, deform, bend, move, or the like.

[0080] The droplet 140 may have a predetermined volume. In some cases, the droplet 140 may be a microfluidic droplet having a volume of the droplet 140 may be between 10’6and 1015liters, although in some examples the volume of the droplet 140 can have any other feasible volume. The gap 130 may be determined, at least in part, by the volume of the droplet 140. In other words, the gap 130 may be chosen or selected such that the droplet 140 (e.g., the volume of the droplet 140) can touch both the first and second sheets 110 and 120.

[0081] FIG. IB shows another view of the microfluidic device 100. In this view, the first sheet 110 may be deflected by a compression force near or adjacent to one side or end of the droplet 140. The compression force creates a reduced gap 132 between the first sheet 110 and the second sheet 120 toward the end or side of the droplet 140. As the reduced gap 132 is formed, the droplet 140 may deform asymmetrically and be drawn toward the reduced gap 132. In some cases, the droplet movement may be caused by differential capillary action and / or a differential pressure gradient within the droplet 140. The compression force may be provided by any feasible means. For example, an array of electro-mechanical, mechanical, and / or pneumatic actuators may be disposed next to the first sheet 110 and / or the second sheet 120 to selectively provide a compression force to form the reduced gap 132. In another example, the compression force may be provided by a stylus that may contact the first sheet 110 and / or the second sheet 120.

[0082] In some examples, the microfluidic device 100 may include one or more optical sensors (not shown). The one or more optical sensors may detect the presence and / or position ofthe droplet 140. In this manner, data from the optical sensors may be used to assist the application of a compression force near or adjacent to the droplet 140.

[0083] FIG. 1C shows another view of the microfluidic device 100. In this view, the compression force on the first sheet 110 has been removed or reduced and the first sheet 110 and the second sheet 120 has returned to an initial position (as shown in FIG. 1A). The gap 130 may be similar to the gap 130 of FIG 1A. The droplet 140 is shown in a second position having moved in response to the compression force described with respect to FIG. IB.

[0084] Thus, in the manner described within FIGS. 1A-1C, any droplet may be manipulated to any area within the microfluidic device 100 by reducing the gap near one end of the droplet. This method advantageously avoids the generation and control of high voltages as well as the need for a plurality of electrodes that are associated with conventional microfluidic devices. The compression force described herein may be provided by any feasible source. For example, mechanical levers, balls, rollers, or the like may apply the compression force to at least one of the first or second sheets 110 and 120, respectively. In some examples, the compression force may be computer or processor controlled. Thus the manipulation of the droplet 140 may be computer and / or processor controlled.

[0085] FIG. ID shows a top view of another exemplary microfluidic device 150. As shown, the microfluidic device 150 may include a series of paths defined by one or more actuation electrodes 155. The actuation electrodes 155 are shown in FIG. ID as a series of squares, each defining a unit cell. These actuation electrodes 155 may have any feasible shape and size and are not limited to squares. For example, the unit cells formed by the actuation electrodes 155 in the first layer may be round, hexagonal, triangular, rectangular, octagonal, parallelogram-shaped, etc. In the example of FIG. ID, the squares representing the unit cells may indicate the physical location of the actuation electrodes 155 in the microfluidic device 150 or may indicate the area where the actuation electrode 155 has an effect (e.g., an effective area such that when a droplet is situated over the denoted area, the corresponding actuation electrode may affect the droplet’ s movement or other physical property). The actuation electrodes 155 may be placed in any pattern. In some examples, actuation electrodes 155 may span the entire corresponding bottom or top surface the air gap of the microfluidic device 150. The actuation electrodes 155 may be in electrical contact with starting sample chambers (not shown) as well as reagent chambers (not shown) for moving different droplets to different regions within the air gap to be mixed with reagent droplets or heated.

[0086] In the microfluidic devices described herein, the first (lower) plate may also include one or more reaction chamber openings (access holes) 160. Access to the reaction chamber wells may allow reaction droplets to be initially introduced or for allowing reagent droplets to beadded later. In particular, one or more reaction droplets may be manipulated in the air gap (moved, mixed, heated, etc.) and temporarily or permanently moved out of the air gap and into a reaction chamber well though a reaction chamber opening. As shown, some of the reaction chamber openings 160 pass through an actuation electrode 155. As will be shown in greater detail herein, the reaction chamber may itself include additional actuation electrodes that may be used to move a reaction chamber droplet into / out of the reaction chamber well. In some variations one or more actuation electrodes may be continued (out of the plane of the air gap) into the reaction chamber well.

[0087] In general, one or more additional reagents may be subsequently introduced either manually or by automated means in the air gap. In some instances, the access holes may be actual access ports that may couple to outside reservoirs of reagents or reaction components through tubing for introducing additional reaction components or reagents at a later time. As mentioned, the access holes (including reaction chamber openings 160) may be located in close proximity to an actuation electrode 155. Access holes may also be disposed on the side or the bottom of the microfluidic device 150. In general, the apparatus may include a controller 165 for controlling operation of the actuation electrodes 155, including moving droplets into and / or out of reaction chambers. The controller 165 may be in electrical communication with the actuation electrodes 155 and it may apply power in a controlled manner to coordinate movement of droplets within the air gap and into / out of the reaction chambers. The controller 165 may also be electrically connected to the one or more temperature regulators (thermal regulators 170) to regulate temperature in the thermal zones 175. One or more sensors (e.g., video sensors, electrical sensors, temperature sensors, etc.) may also be included (not shown) and may provide input to the controller which may use the input from these one or more sensors to control motion and temperature.

[0088] FIG. 2 shows block diagram illustrating example microfluidic processing 200. Any of the devices described herein may be used in part or in whole to perform some or all of the microfluidic processing. The microfluidic processing 200 may be performed on or with any feasible liquid 210. In some cases the liquid 210 may be a biologic liquid that may include one or more deoxyribonucleic acid (DNA) molecules for sequencing.

[0089] The fluid liquid may undergo sample processing 220. Sample processing 220 may include the addition of one or more reagents and / or surfactants to the liquid 210. In some cases, reagents needed for downstream processing may be added during sample processing 220. For example, forward and reverse primers, DNA polymerase, deoxynucleotide triphosphates (dNTPs) and reaction buffers may be added during sample processing 220. Alternatively or in addition, surfactants may be added. In some examples, non-ionic surfactants may be added to theliquid 210. Some example non-ionic surfactants can include, but are not limited to, TERGITOL, TWEEN, and PLURONIC surfactants. Examples of TERGITOL surfactants include TERGITOL 15-S-5 (e.g., secondary alcohol ethoxylate with 5 ethylene oxide units, CAS number 84133-50-6), TERGITOL 15-S-7 (e.g., secondary alcohol ethoxylate having a Cl 1-15 secondary alcohol with 7 moles of ethylene oxide, CAS number: 84133-50-6), TERGITOL 15-S-9 (e.g., secondary alcohol ethoxylate having a C12-14 secondary alcohol with 9 ethylene oxide units, also referred to as "C12-14 Pareth-9”), TERGITOL NP40S (e.g., Nonylphenol Ethoxylate, also referred to a Nonyl phenoxypolyethoxylethanol), TERGITOL NP9 (e.g., Nonylphenol ethoxylate, also referred to as NP-9), TERGITOL NP10 (e.g., nonylphenol ethoxylate, also referred to as Nonoxynol-10 or NP-10), and TERGITOL 15-S-12 (e.g., secondary alcohol ethoxylate, Cl 1-15 Pareth 12, which indicates a mixture of secondary alcohols with 11 to 15 carbon atoms, ethoxylated with 12 moles of ethylene oxide).

[0090] Example TWEEN surfactants can include TWEEN 20 (also referred to as Polysorbate 20 or polyoxyethylene (20) sorbitan monolaurate) and TWEEN 80 (Polysorbate 80 or polyoxyethylene sorbitan monooleate). Example PLURONIC surfactants can include PLURONIC F-127 (e.g., Poloxamer 407, a triblock copolymer composed of a hydrophobic polyoxypropylene (PPO) middle section flanked by two hydrophilic polyoxyethylene (PEO) blocks), PLURONIC 25R2 (e.g., polyoxypropylene-polyoxyethylene block copolymer, a synthetic block copolymer made up of a hydrophobic polyoxypropylene chain sandwiched between two hydrophilic polyoxyethylene chains), PLURONIC F-68 (a triblock copolymer composed of a central polypropylene oxide chain flanked by two polyethylene oxide chains (PEO-PPO-PEO)), PLURONIC P123 (e.g., polyethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), abbreviated as PEO-PPO-PEO, a triblock copolymer made up of these repeating units, with the "PPO" block being the hydrophobic core and the "PEO" blocks forming the hydrophilic corona), PLURONIC L 61 (Poloxamer 181, Polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO), also referred to as Synperonic L 61), and PLURONIC 17R4 (e.g., polypropylene glycol)-block-poly(ethylene glycol)-block-poly (propylene glycol). Non-ionic surfactants can increase droplet mobility, especially in MAOS systems. Additionally, non-ionic surfactants may prevent or reduce evaporation of the liquid 210 during processing.

[0091] Next, the liquid 210 (after sample processing 220) can undergo microfluidic manipulation 230. For example, one or more droplets of liquid 210 can be introduced into and processed by a MAOS system. In another example, one or more droplets of liquid 210 can be introduced into and be processed by a microfluidic apparatus that uses electro wetting to manipulate droplets. In either case, the microfluidic manipulation 230 may include processing ofthe liquid 210 for DNA sequencing. For example, sample enrichment, Nucleic acid extraction, library preparation and amplification, target enrichment, and the like may be performed as part or all of the microfluidic manipulation 230.

[0092] Next, the liquid 210 is extracted or removed from the microfluidic apparatus performing the microfluidic manipulation 230 and provided to a DNA sequencer 240. The DNA sequencer can be any feasible device capable of sequencing all or part of a DNA molecule. One example of a DNA sequencer 240 is a nanopore sequencer. A nanopore sequencer passes segments of a single strand of the DNA molecule through a tiny pore. Each DNA base (adenine (A), cytosine (C), guanine (G), and thymine (T) may cause a characteristic electrical current perturbation to be emitted by the nanopore. The DNA molecule can then be sequenced by identifying the current perturbations and logging or recording the DNA base associated with the current perturbation.

[0093] Another example DNA sequencer 240 uses a light sensor to detect fluorescence that may be emitted by a nucleotide. The nucleotides may be treated to fluoresce and be bound to DNA bases of the DNA molecule being sequence. In some examples, the nucleotides may be illuminated by a laser.

[0094] In either example, the DNA base data from the DNA sequencer 240 may be analyzed and assembled into a listing of the DNA sequence. The DNA sequence can be stored as sequence data 250. The sequence data 250 may be stored locally or remotely. For example, the sequence data 250 may be stored on a remote cloud server or cloud storage device.

[0095] In some examples, a non-ionic surfactant that is added to the liquid 210 may improve droplet handling during microfluidic manipulation 230. In some cases, the non-ionic surfactant can improve droplet mobility as well as reduce droplet evaporation. The action of the non-ionic surfactant may be discussed with the context of a microfluidic manipulation device.

[0096] FIG. 3 shows an example microfluidic manipulation device 300. Elements, the number of elements, and implementation of the elements may differ from any implementation of the microfluidic manipulation device 300. Thus, the elements of the microfluidic manipulation device 300 are exemplary rather than limiting. The microfluidic manipulation device 300 may include a base 310, a cartridge 320, an actuator 330, and a controller 340.

[0097] In general, the cartridge 320 can receive droplets (such as droplets of liquid 210 from FIG. 2). One droplet 323 is shown, however the cartridge 320 may hold any number of droplets. Furthermore, FIG.2 shows the microfluidic manipulation device 300 in cross-section. Cross-sectional views generally cannot show three-dimensional aspects of devices, including the microfluidic manipulation device 300.

[0098] The cartridge 320 can include a first sheet 321 and a second sheet 322. The first sheet 321 may be held or positioned a predetermined distance from the second sheet 322. Furthermore, surfaces (inner surfaces of the first sheet 321 and the second sheet 322 that may contact the droplet 323) may include a hydrophobic coating. In some cases, the first sheet 321 and the second sheet 322 may be formed from a hydrophobic material. In some examples the first sheet 321 and / or the second sheet 322 may deform under external pressure.

[0099] For example, the actuator 330 may include a deforming device 331. In some examples, the deforming device 331 may include a wheel or other feasible device. The deforming device 331 may apply pressure to the first sheet 321 and reduce the distance between the first sheet 321 and the second sheet 322. In some cases, reducing the distance between the first sheet 321 and the second sheet 322 next to the droplet 323 can cause the droplet 323 to move within a gap between the first sheet 321 and the second sheet 322. Typically, the droplet 323 can move toward the region of reduced distance in the gap. The controller 340 can control the actuator 330 that can in turn control the location of the droplet 323 within the cartridge 320.

[0100] In some other examples, the base 310 can include a plurality of electrodes 311. The controller 340 can provide a voltage to one or more of the electrodes 311 near the droplet 323. An electric field generated by the provided voltage can change a surface tension of the droplet 323 and cause the droplet to move within the gap of the cartridge 320 through electro wetting.

[0101] In some implementations, adding a surfactant, such as a non-iconic surfactant, to a liquid before droplet manipulation can improve manipulation outcomes. The surfactant can increase droplet mobility, reduce fouling, and / or reduce evaporative losses. FIG. 4 describes a method for manipulation liquids, such a biologic solutions using a surfactant.

[0102] FIG. 4 is a flowchart showing an example method 400 for manipulating a liquid with a microfluidic device. Some examples may perform the operations described herein with additional operations, fewer operations, operations in a different order, operations in parallel, and some operations differently. The method 400 is described below with respect to microfluidic manipulation device 300, however, the method 400 may be performed by any other suitable system or device.

[0103] The method 400 begins in block 402 as a biologic solution is obtained or received. A biologic solution can be any feasible liquid solution. For example, the biologic solution can include DNA molecules in a liquid that also includes reagents to be used with genomic sequencing such as primers, indicators such as fluorescent tags, and the like.

[0104] Next, in block 404 a surfactant can be added to the biologic solution. In some examples the surfactant is added in a range between 0.0005% to 3.0% w / v (percent weight / percent volume). In some implementations, a surfactant amount of 0.05% w / v can besufficient, however any feasible amount is possible. The surfactant can be any feasible surfactant, including non-ionic surfactants. Examples of non-ionic surfactants include TERGITOL TWEEN, and PLURONIC surfactants.

[0105] Next, in block 406 the biologic solution is processed with a microfluidic device, such as the microfluidic manipulation device 300. Example processing may include preparing DNA molecules for sequencing. Some processing within the microfluidic manipulation device 300 may include sample enrichment, Nucleic acid extraction, library preparation and amplification, target enrichment. Other examples of processing can include manipulation within the microfluidic manipulation device 300. The processing described herein is not meant to be exhaustive, but rather exemplary.

[0106] In some examples, microfluidic manipulation can include introducing one or more droplets into the cartridge 320 and manipulating the droplets by reducing a gap of the cartridge 320 near any of the droplets. The surfactant (added in block 404) may enable the droplets to move more freely within the cartridge 320.

[0107] In another example, microfluidic manipulation can include introducing one or more droplets into the cartridge 320 and manipulating the droplets by providing a high voltage to one or more electrodes 311 within the base 310. The high voltage can induce or generate an electric field that can move the droplets through electrowetting.

[0108] In some examples, prior to introducing droplets into any part of the microfluidic manipulation device, the droplets may be surrounded with an evaporation reducing reagent. The evaporation reducing reagent may be used in addition to any surfactant that has already been added to the biologic solution.

[0109] Next in block 408, the biologic solution can be extracted (removed) from the microfluidic manipulation device 300. For example, any processing of the biologic solution that has occurred within the microfluidic manipulation device 300 may be complete, and the biologic solution is ready for further processing in another device. One example of further processing may include DNA sequencing of one or more segments (or all) of a DNA molecule included with the biologic solution. Any other feasible processing is possible.

[0110] FIG. 5A shows an example cartridge 500 for use with a microfluidic manipulation device 300, however the cartridge 500 may be used with any feasible microfluidic device. In some examples, the cartridge 500 may be an example of the cartridge 320 of FIG. 3.

[0111] As shown the cartridge 500 may include eight channels 501, 502, 503, 504, 505, 506, 507, and 508, however other cartridges may include any number of channels. Each of the channels 501-508 can be isolated from each other. In other words, any of the channels may not be in liquid communication with any other channel.

[0112] The channels 501-508 may each include the following features described with respect to channel 501. That is, channels 501-508 may all include similar features, however, only the features of channel 501 are described to simplify the description.

[0113] Channel 501 can include a waste reservoir 510. The waste reservoir 510 can hold undesired reaction products that are generated or accumulated within channel 501. Channel 501 can also include an inlet 520 and reaction zones 530, 531, 532, 533, 534, and 535. A droplet may be inserted into the channel 501 through the inlet 520. The droplet may be moved / manipulated to and through zones 530-535 as the droplet is processed. Each of the zones may enable different processing steps to be performed. Some zones may include heater units, cooling units, magnetic actuators (to actuate magnetic beads) or any other feasible units.

[0114] In some examples, microfluidic manipulation can begin as a droplet is placed in the inlet 520. An actuator (not shown) can move the droplet through one or more of the zones 530-535. In some cases, the actuator can move all or part of the droplet to the waste reservoir 510. Further processing can include moving the droplet from any of the zones 530-535 back to the inlet 520 where the droplet can then be extracted from the cartridge 500.

[0115] FIG. 5B is a schematic drawing 550 showing an example droplet flow for the cartridge 500. As discussed herein, a droplet may enter the cartridge via an inlet 551 and be manipulated through one or more zones 552. At the completion of processing, the droplet is moved toward the inlet 551 for removal from the cartridge 500.

[0116] FIG. 6 shows a partial view of an example microfluidic manipulation device 600. The microfluidic manipulation device 600 may include actuators 610, a base 620, and a cartridge 630. The microfluid manipulation device 600 can be another example of the microfluidic manipulation device 300 of FIG. 3. The actuators 610 can place pressure on at least one sheet of the cartridge 630 to reduce a gap between sheets of the cartridges 630 and move or manipulate a droplet therein.

[0117] FIG. 7 shows simplified view 700 a cartridge during different stages of processing within a microfluidic manipulation device. As shown in FIG. 7, 50 pF droplets containing DNA-attached magnetic beads, treated with 0.05% TERGITOL surfactant, exhibited consistent mobility while transitioning smoothly to the magnetic zones (Zone F) of the device. The droplets were incubated at 48°C for 10 minutes, followed by 37°C for 30 minutes to facilitate DNA elution from the beads. Once the magnet was engaged, the supernatant containing the eluted DNA was moved to the inlet for retrieval. The entire elution process occurred without any droplet stalling or fouling, based, at least in part, to the addition of TERGITOL.

[0118] FIG. 8 shows test data graphs 800 regarding read length of DNA molecule segments. Graph 810 shows read length data associated with DNA molecule segments that have not beentreated with TERGITOL. Note that for this test data the N50 value (the median number of bases in a segment that are read) is about 37.37 kilobases (kb).

[0119] Graph 820 shows read length data associated with DNA molecule segments that have been treated with TERGITOL. For this test data, the N50 value is about 36.27 kb. One conclusion is that TERGITOL does not affect sequencing read quality. Surprisingly, only surfactants comprising secondary alcohol ethoxylates (nonionic surfactant made from ethoxylated secondary alcohols) were effective without the use of dropgloss.

[0120] In some examples, a non-ionic surfactant can improve DNA sequencing. This is described with respect to FIGS. 9-11.

[0121] FIG. 9 is a flowchart showing an example method 900 for sequencing a DNA sample. The method 900 is described below with respect to a pore-based DNA sequencer, however, the method 900 may be performed by any other suitable system or device.

[0122] The method 900 begins in block 902 as a DNA sample is obtained or received. A DNA sample can include any one or more DNA segments within any feasible liquid solution. In some examples, the DNA sample solution can include DNA molecules in a liquid that also includes reagents to be used with genomic sequencing such as primers, indicators such as fluorescent tags, and the like.

[0123] Next, in block 904 a surfactant is added to the biologic solution. In some examples the surfactant is added in a range between 0.0005% to 3.0% w / v (percent weight / percent volume). In some implementations, a surfactant amount of 0.05% w / v can be sufficient, however any feasible amount is possible. The surfactant can be any feasible surfactant, including nonionic surfactants. Examples of non-ionic surfactants include TERGITOL, TWEEN, and PLURONIC surfactants.

[0124] Next, in block 906 DNA sequencing is performed. DNA sequencing can determine nucleotide sequences of the DNA (or in some cases a ribonucleic acid (RNA)) molecule.Typically, the determined nucleotide sequences may include partial nucleotide sequences. The length of the nucleotide sequences are measured in terms of nucleotide pairs.

[0125] In some examples, the DNA sequencing may be performed by a pore-based DNA sequencer. Pore-based sequencing (sometimes referred to as nanopore sequencing) is an advanced technology that enables real-time analysis of long DNA or RNA molecules by measuring changes in ionic current as they pass through a nanoscale pore, allowing the identification of nucleotide sequences. This technique offers significant advantages over methods, such as the ability to sequence long DNA fragments in a single run, providing a more comprehensive view of complex genomes. However, achieving high-quality and high-yieldDNA readings requires optimization of factors such as sample preparation, efficient DNA translocation, and pore stability.

[0126] A non-ionic surfactant, such as TERGITOL, TWEEN, or PLURONIC surfactants, can improve the performance of a DNA sequencer, such as a pore-based DNA sequencer by reducing DNA aggregation, thereby ensuring a uniform distribution of molecules entering the nanopore. The non-ionic surfactant can also prevent pore clogging by minimizing protein-DNA interactions and debris buildup on or near the pore, allowing continuous sequencing.Additionally, lower surface tension due to the surfactant facilitates smoother sample loading, stabilizes motor proteins, and promotes consistent DNA translocation, thereby leading to longer reads and higher throughput. As described herein a nonionic surfactant made from ethoxylated secondary alcohol may be particularly useful.

[0127] FIG. 10 shows test data graphs 1000 regarding read length of DNA molecule segments using pore-based DNA sequencers. Graph 1010 shows read length data associated with DNA molecule segments that have not been treated with TERGITOL (a non-ionic surfactant) as read by a pore-based DNA sequencer. The graph 1010 shows an N50 value of about 27.98 kb. Total reads are about 54.8 mb.

[0128] Graph 1010 shows read length data associated with DNA molecule segments that have been treated with a 0.05% (w / v) solution of TERGITOL. Graph 1020 shows an N50 value of about 39.37 kb. The increase in the N50 value of graph 1020 may indicate a better quality of sequencing data with longer more continuous reads. Further, the total reads in graph 1020 are about 77 mb. The increase in total reads shows a substantial improvement in sequencing yield. Thus, the non-ionic surfactant may enhance both the quality and quantity of DNA sequencing outputs.

[0129] FIG. 11 shows pore occupancy data 1100 for a DNA elution with and without using a non-ionic surfactant. Graph 1110 shows pore occupancy data over time for a DNA elution without a non-ionic surfactant. High pore occupancy may indicate more pore usages for porebased DNA sequencers. Graph 1120 shows pore occupancy over time for a DNA elution that includes a non-ionic surfactant. As shown, pore occupancy is more consistent which may yield better reads.

[0130] In general, any of these mechanical microfluidic apparatuses (e.g., device, system or the like) for controlled liquid manipulation may include a two-dimensional (planar) fluidic chamber. The chamber may include a first sheet and a second sheet separated by a gap therebetween. The gap may separate the first and second sheets by any feasible distance. The first and second sheets may be hydrophobic or may include hydrophobic coatings.

[0131] As described above, microfluidic droplets may be manipulated through mechanical manipulation that applies forces directly or indirectly to the first sheet or second sheet selectively reducing the gap.

[0132] FIG. 12 is an exploded view of an example microfluidic system 1200. The microfluidic system 1200 may include a base unit 1210, a conforming surface 1220, a cartridge 1230, a hold down 1240, an actuator 1250, a vacuum pump 1260, and a controller 1270. The microfluidic system 1200 may include some or all of the elements of the microfluidic device 100 of FIG. l.For example, the cartridge 1230 may include a first sheet 1231 and a second sheet (occluded by the first sheet 1231) that may be examples of the first sheet 110 and the second sheet of the microfluidic device 1200.

[0133] The cartridge 1230 may be configured to include one or more channels 1232. Each channel 1232 can be fluidically isolated from an adjacent channel. Each channel 1232 can include an inlet 1233. The inlet 1233 is an opening within one of the sheets (shown here as the first sheet 1231) that allows a microfluidic droplet to be inserted into the channel 1232. In some examples, the droplet may be mixed with a surfactant, including non-ionic surfactants, prior to being inserted into the inlet 1233. The surfactant may reduce or prevent evaporation and in some cases may increase mobility of the droplet withing the cartridge 1230.

[0134] The base unit 1210 may be coupled to the conforming surface 1220. In some examples, the conforming surface may be integral with the base unit 1210. The conforming surface 1220 may be able to modify a shape of one of the sheets of the cartridge 1230. For example, the conforming surface 1220 may include one or more features that can contact one of the sheets of the cartridge 1230. In some examples, a vacuum pump 1260 may be coupled to the conforming surface 1220. The conforming surface 1220 may include one or more slots, holes, channels or the like that direct a vacuum from the vacuum pump 1260 toward the cartridge 1230. Thus, when the cartridge 1230 is disposed onto the conforming surface 1220, the vacuum can draw a sheet of the cartridge 1230 to the conforming surface 1220 and cause the sheet of the cartridge 1230 to take a shape determined by the conforming surface 1220.

[0135] In some examples, the conforming surface 1220 may include one or more inlet wells 1225. The inlet wells 1225 may be disposed on the conforming surface 1220 such that the inlet wells 1225 are positioned beneath the inlet 1233 when the cartridge 1230 is placed on the base 1210 (on the conforming surface 1220). Thus, when the cartridge 1230 is placed on the base 1210, and a vacuum applied, a sheet of the cartridge can take the shape of the conforming surface 1220. In particular, a sheet of the cartridge 1230 can take the shape of the inlet well 1225 (be conformed to the shape of the inlet well 1225) under the inlet 1233. In some examples, the inlet well 1225 may have a convex shape. Therefore, the sheet of the cartridge can conform tothe convex shape. In some cases, the inlet well 1225 can affect a behavior of a droplet (microfluidic droplet) inserted into the channel 1232 through the inlet 1233. In some examples, the inlet well 1225 may be configured to capture or hold a predetermined amount of liquid.

[0136] The hold down 1240 may assist in positioning the cartridge 1230 onto the base unit 1210. In addition, the hold down 1240 may include one or more grooves 1241 that can receive and guide all or part of the actuator 1250. The actuator 1250 may include one or more elements that can apply pressure to the cartridge 1230 and reduce a distance between the first sheet 1231 and the second sheet (not shown).

[0137] The controller 1270 can control operation of the vacuum pump 1260 and the actuator 1250. For example, the controller 1270 can operate the vacuum pump 1260 to provide a vacuum to the conforming surface 1220 and cause a sheet of the cartridge 1230 to take the shape of the conforming surface 1220. Additionally, the controller 1270 can position the actuator 1270 to any feasible position on the cartridge 1230. In some examples, the controller 1270 can cause the actuator to reduce a distance between sheets of the cartridge 1230 and cause any droplets within the cartridge 1230 to move within a channel 1232.

[0138] FIG. 13 shows a partial view of an example microfluidic system 1300. The microfluidic system 1300 can include a hold down 1310 and a cartridge 1320. The hold down 1310 can be an example of the hold down 1240 and the cartridge 1320 can be an example of the cartridge 1230 of FIG. 2. The hold down 1240 can accommodate any feasible number of channels. As shown in the example of FIG. 13, the hold down 1240 can include eight channels 1311. The hold down may be referred to as a support.

[0139] The cartridge 1320 can include a first sheet 1322 and a second sheet (occluded by the first sheet 1322) that are separated from each other by a predetermined distance. The cartridge 1320 can include a number of discrete and isolated channels. Each channel may not be in fluid communication with any other channel. Each channel may have an associated inlet 1321 through which a droplet may be inserted into a channel.

[0140] An inlet well (not shown) may be disposed under the inlet 1321 to receive, position, and / or guide the droplet inserted through the inlet 1321. In some examples, the inlet well may position the droplet such that a portion of the droplet 1330 is in contact with the first sheet 1320. In some examples, the inlet well can collect a droplet from the channel and position the droplet under or near the inlet 1321 thereby enabling drop extraction from the cartridge 1320.

[0141] FIG 14A shows a partial view of an example conforming surface 1400. The conforming surface 1400 can support any number of channels; the example conforming surface 1400 can support eight channels 1430.

[0142] Each channel can include an inlet well 1410. The inlet well 1410 may be disposed below the inlet of the cartridge (not shown). The shape of the inlet well 1410 can be any feasible shape. As shown, the inlet well 1410 can be oval shaped, elongate oval shaped, tear drop shaped, or any other shape. The shape of the inlet well 1410 can affect droplet position when a liquid is inserted into the inlet.

[0143] The conforming surface 1400 can also include one or more grooves, slots, or openings 1411 that allow a vacuum to be applied to a cartridge disposed on the conforming surface 1400. More particularly, the vacuum would cause a sheet of a cartridge to take the shape of the conforming surface 1400.

[0144] FIG. 14B shows another partial view of the conforming surface 1400. The inlet wells 1410 are positioned near ends of the channel. Each channel 1440 can have a separate inlet well 1410. The conforming service 1400 can also include any number of grooves 1411 for providing a vacuum through the conforming surface 1400 to the cartridge.

[0145] FIG. 15 shows an example actuator assembly 1500. The actuator assembly 1500 may include one actuator 1510 per channel. Each actuator 1510 may be spring loaded to provide a predetermined amount of pressure or force to a cartridge (not shown) and reduce the predetermined distance between sheets of the cartridge and move a droplet of liquid.

[0146] FIG. 16 is a flowchart showing an example operation 1600 for manipulating a microfluidic droplet. Some examples may perform the operations described herein with additional operations, fewer operations, operations in a different order, operations in parallel, and some operations differently. The operation 1600 is described below with respect to the microfluidic system 200 of FIG. 2, however, the operation 1600 may be performed by any other suitable system or device.

[0147] The operation 1600 begins in block 1602 as a cartridge 230 is attached to the base unit 210. In some examples, the base unit 210 may include a conforming surface 220. In some examples, the cartridge 230 may include a first sheet 210 (an upper sheet) and a second sheet separated by a predetermined distance from the first sheet 210. One or more sheets of the cartridge 230 may be flexible and can conform to the shape of the conforming surface 220. In some examples the hold down 1240 may be used to position and affix the cartridge 230 to the base unit 210.

[0148] Next, in block 1604 a vacuum is applied to the cartridge 230 through the base unit. In some examples, the vacuum is provided by the vacuum pump 260 which is received through the base unit 1210 and provided to the conforming surface 1210. The conforming surface 1210 may include one or more slots, grooves, or ports that can direct the vacuum to at least one sheet of the cartridge 1230. Thus, the vacuum can cause one sheet of the cartridge to be shaped by theconforming surface 1210. In some examples, the conforming surface 1210 may include an inlet well and one sheet of the cartridge 1230 can be shaped by the inlet well.

[0149] Next, in block 1606 a droplet is introduced into the cartridge. For example, the cartridge 1230 can include one or more inlets 1233 through which a droplet can be inserted into a predetermined gap between sheets. In some cases, the droplet can be received or deposited into the inlet well.

[0150] In some examples, the droplet may be mixed with a surfactant prior to being inserted into the cartridge 1230. The surfactant, which may be a non-ionic surfactant, may prevent or reduce evaporation, or in some cases improve mobility within the cartridge 1230.

[0151] Next, in block 1608 the droplet is moved within the cartridge 1230. For example, the actuators 1250 may be used to reduce the predetermined distance between sheets of the cartridge 1230 next to the droplet. Reducing the predetermined distance may cause the droplet to move within the cartridge.

[0152] In some examples, the actuators 1250 may move the droplet to a heating zone to process the droplet. In some other examples, the actuators 1250 may move and return the droplet to the inlet well for removal from the cartridge 1230. The inlet well may also correspond to a removal region.

[0153] FIG. 17 shows a block diagram of a device 700 that may be an example of any microfluidic device or system described herein. The device 700 may include a vacuum pump 710, a base unit 720, a cartridge 725, an actuator 750, a processor 730, and a memory 740.

[0154] The cartridge 725 may be an example of the cartridge 1230 of FIG. 12, or any other feasible cartridge described herein. In some examples, the cartridge 725 may include a first sheet and a second sheet, separated by a predetermined distance from the first sheet. In some examples, the first sheet and the second sheet may be hydrophobic sheets and / or coated with a hydrophobic material. The first sheet and / or the second sheet may be a flexible and / or conformable material.

[0155] In some examples, the base unit 720 may be configured to receive the cartridge 725. The base unit 720 may include a conforming surface 721 that can include one or more features that shape a surface (sheet) of the cartridge 725. The vacuum pump 710 may be coupled to the base unit 720 and can provide a vacuum that can affix or attach the cartridge 725 to the conforming surface and / or the base unit 720. The vacuum pump 710 may be coupled to the processor 730.

[0156] The actuator 750, which is coupled to the processor 730, may selectively apply pressure to the cartridge 725 to reduce a distance (reduce the predetermined distance) betweensheets of the cartridge 725. In some examples, the actuator 750 can cause droplets inserted into the cartridge 725 to move.

[0157] The memory 740 may include a non-transitory computer-readable storage medium (e.g., one or more nonvolatile memory elements, such as EPROM, EEPROM, Flash memory, a hard drive, etc.) that may store the following software modules: an actuator control module 742 to control the pressure actuator 750; and a vacuum control module 744. Each software module includes program instructions that, when executed by the processor 730, may cause the device 700 to perform the corresponding function(s). Thus, the non-transitory computer-readable storage medium of memory 740 may include instructions for performing all or a portion of the operations described herein.

[0158] The processor 730 may execute the actuator control module 742 to manipulate one or more microfluidic droplets disposed between at least two hydrophobic sheets by applying forces through the actuator 750. For example, execution of the actuator control module 742 may cause compressive, pinning, and / or actuation forces to be applied to at least one of the sheets of the cartridge 725. The forces may be selectively applied to move, separate, combine, and / or mix one or more microfluidic droplets. In some examples, execution of the pressure control module 742 may cause a roller or wheel to move across at least one of the sheets, apply a compression force, and cause a droplet to move.

[0159] The processor 730 may execute the vacuum control module 744 to selectively control, enable, and / or disable the vacuum pump 710. In some examples, execution of the vacuum control module 744 may cause power to be applied to the vacuum pump 710 and thereby provide a vacuum (negative pressure) to the base unit 720. In some examples, the vacuum may cause at least one sheet of the cartridge to be drawn toward and shaped by the conforming surface 721.

[0160] In some examples, the processor 730 in conjunction with the memory 740 may perform operations associated with the controller 270.

[0161] When a feature or element is herein referred to as being “on” another feature or element, it can be directly on the other feature or element or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being “directly on” another feature or element, there are no intervening features or elements present. It will also be understood that, when a feature or element is referred to as being “connected”, “attached” or “coupled” to another feature or element, it can be directly connected, attached or coupled to the other feature or element or intervening features or elements may be present. In contrast, when a feature or element is referred to as being “directly connected”, “directly attached” or “directly coupled” to another feature or element, there are no intervening features or elements present.Although described or shown with respect to one embodiment, the features and elements so described or shown can apply to other embodiments. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.

[0162] Terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items and may be abbreviated as “ / ”.

[0163] Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms “upwardly”, “downwardly”, “vertical”, “horizontal” and the like are used herein for the purpose of explanation only unless specifically indicated otherwise.

[0164] Although the terms “first” and “second” may be used herein to describe various features / elements (including steps), these features / elements should not be limited by these terms, unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another feature / element. Thus, a first feature / element discussed below could be termed a second feature / element, and similarly, a second feature / element discussed below could be termed a first feature / element without departing from the teachings of the present invention.

[0165] Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising” means various components can be co-jointly employed in the methods and articles (e.g., compositions and apparatuses including device and methods). For example, the term“comprising” will be understood to imply the inclusion of any stated elements or steps but not the exclusion of any other elements or steps.

[0166] In general, any of the apparatuses and methods described herein should be understood to be inclusive, but all or a sub-set of the components and / or steps may alternatively be exclusive and may be expressed as “consisting of’ or alternatively “consisting essentially of’ the various components, steps, sub-components or sub-steps.

[0167] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word “about” or “approximately,” even if the term does not expressly appear. The phrase “about” or “approximately” may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical values given herein should also be understood to include about or approximately that value, unless the context indicates otherwise. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “X” is disclosed the “less than or equal to X” as well as “greater than or equal to X” (e.g., where X is a numerical value) is also disclosed. It is also understood that the throughout the application, data is provided in a number of different formats, and that this data represents endpoints and starting points, and ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point “15” are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0168] Although various illustrative embodiments are described above, any of a number of changes may be made to various embodiments without departing from the scope of the invention as described by the claims. For example, the order in which various described method steps are performed may often be changed in alternative embodiments, and in other alternative embodiments one or more method steps may be skipped altogether. Optional features of various device and system embodiments may be included in some embodiments and not in others.Therefore, the foregoing description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the invention as it is set forth in the claims.

[0169] The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. As mentioned, other embodiments may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is, in fact, disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.

Claims

CLAIMSWhat is claimed is:

1. A method for performing microfluidic manipulation of a droplet, the method comprising:introducing the droplet into an air gap formed between a first sheet that is elastically deformable and a second sheet, wherein the droplet comprises a nonionic surfactant made from ethoxylated secondary alcohol so that a contact angle of the droplet within the air gap is between 38 degrees and 42 degrees;applying a compression force against the first sheet using a mechanical force applicator to form a region of locally reduced gap width within the air gap that is adjacent to droplet, thereby drawing the droplet towards the region of locally reduced air gap; andmoving the droplet within the air gap by translating the mechanical force applicator along an outer surface of the first sheet to translate the region of locally reduced gap width within the air gap so that the droplet follows the mechanical force applicator.

2. The method of claim 1, wherein the first sheet, the second sheet, or the first and second sheets comprise a hydrophobic surface configured to contact the droplet.

3. The method of claim 1, wherein the liquid droplet comprises a biologic liquid.

4. The method of claim 1, wherein the concentration of the nonionic surfactant is between about 1% and 6%.

5. The method of claim 1, further comprising removing the droplet from the microfluidic manipulation device.

6. The method of claim 1, wherein the droplet does not include a hydrophobic shell.

7. The method of claim 1, further comprising introducing the droplet to the microfluidic manipulation device at a first location in a cartridge that includes the first sheet and the second sheet separated by a predetermined distance to form the gap therebetween.

8. The method of claim 1, wherein applying the compression force comprises reducing the air gap by a predetermined amount adjacent to the droplet.

9. The method of claim 1, further comprising affixing a cartridge that includes the first sheet and the second sheet to a base prior to introducing the droplet into the cartridge.

10. The method of claim 1, further comprising adding the nonionic surfactant to the droplet before the droplet is introduced into the air gap.

11. The method of claim 1, further comprising adding the nonionic surfactant to the droplet while the droplet is within the air gap.

12. The method of claim 1, wherein the first sheet and the second sheet are hydrophobic.

13. The method of claim 1, wherein surfaces of the first sheet and the second sheet disposed toward the gap are treated with a hydrophobic coating.

14. The method of claim 1, wherein the surfactant comprises TERGITOL.

15. A method for performing microfluidic manipulation of a droplet, the method comprising:introducing the droplet into an air gap formed between a first sheet that is elastically deformable and a second sheet, wherein the droplet comprises a nonionic surfactant at a concentration such that a contact angle of the droplet within the air gap is between 38 degrees and 42 degrees on a hydrophobic surface of the first sheet, the second sheet or the first and second sheets;applying a compression force against the first and / or second sheet using a mechanical force applicator to form a region of locally reduced gap width within the air gap that is adjacent to droplet, thereby drawing the droplet towards the region of locally reduced air gap; andmoving the droplet within the air gap by translating the mechanical force applicator along an outer surface of the first sheet to translate the region of locally reduced gap width within the air gap so that the droplet follows the mechanical force applicator.

16. A method comprising:receiving or obtaining a biologic liquid that includes at least one deoxyribonucleic acid (DNA) molecule;adding a surfactant to the biologic liquid; andsequencing a droplet of a mixture of the biologic liquid and the surfactant to determine at least a partial nucleotide sequence of the one at least one DNA molecule.

17. The method of claim 16, wherein sequencing the droplet includes sequencing with a pore-based DNA sequencer.

18. The method of claim 16, wherein the surfactant is a non-ionic surfactant.

19. The method of claim 16, wherein the surfactant includes TERGITOL, TWEEN, PLURONIC or a combination thereof.

20. The method of claim 16, wherein the surfactant is added in an amount of about 0.05% w / v (percent weight / percent volume) with respect to the biologic liquid.

21. The method of claim 16, wherein the surfactant is added in a range of between 0.0005% to 3.0% w / v with respect to the biologic liquid.

22. A microfluidic device comprising:a cartridge including:a first sheet;a second sheet, wherein the first sheet is separated from the second sheet by a predetermined distance to form a gap between the first sheet and the second sheet;and at least one inlet on the first sheet configured to receive a microfluidic droplet into the gap;a base unit configured to receive the cartridge, the base unit comprising:at least one inlet well positioned under the inlet when the cartridge is coupled to the base unit; andone or more vacuum ports configured to apply a vacuum the second sheet and cause the second sheet to conform at least to a shape of the at least one inlet well.

23. The microfluidic device of claim 22, wherein the inlet well is configured to capture a predetermined volume of liquid comprising the microfluidic droplet.

24. The microfluidic device of claim 22, wherein the vacuum at least partially conforms the second sheet to the inlet well.

25. The microfluidic device of claim 22, wherein the inlet well has an elongate oval shape.

26. The microfluidic device of claim 22, wherein the inlet well comprises a tear drop shape.

27. The microfluidic device of claim 22, further comprising a hold down configured to fit over and position the cartridge with respect to the base unit.

28. The microfluidic device of claim 27, wherein the hold down includes one or more grooves to receive an actuator to selectively reduce the predetermined distance in the gap.

29. The microfluidic device of claim 22, further comprising an actuator configured to reduce the predetermined distance between the first sheet and the second sheet.

30. The microfluidic device of claim 29, wherein the actuator is further configured to move the microfluidic droplet from a region near the inlet to other regions between the first sheet and the second sheet.

31. The microfluidic device of claim 29, further comprising a controller configured to actuate and move the actuator.

32. The microfluidic device of claim 22, further comprising a vacuum pump configured to supply the vacuum to the base.

33. The microfluidic device of claim 32, further comprising a controller configured to control the vacuum pump.

34. The microfluidic device of claim 22, further comprising a heater disposed within the base.

35. The microfluidic device of claim 22, wherein the first sheet and the second sheet are hydrophobic.

36. The microfluidic device of claim 22, wherein a first surface of the first sheet and a first surface of the second sheet are disposed toward the gap and are treated with a hydrophobic coating.

37. The microfluidic device of claim 22, wherein the second sheet is disposed against the base unit.

38. The microfluidic device of claim 22, further comprising a controller configured selectively reduce the predetermined distance in one or more regions within the gap adjacent to the microfluidic droplet, wherein the reduced predetermined distance moves the microfluidic droplet within the cartridge.

39. A method of manipulating one or more microfluidic droplets comprising:attaching a cartridge onto a base unit, wherein the cartridge includes a first sheet, a second sheet, and a gap therebetween, further wherein the base unit includes a conforming surface configured to receive the cartridge;applying a vacuum through the conforming surface causing the second sheet to conform to a shape of the conforming surface;introducing a microfluidic droplet though an inlet of the cartridge and into the gap of the cartridge; andselectively reducing, by an actuator, the gap in one or more regions adjacent to the microfluidic droplet so as to move the microfluidic droplet.

40. The method of claim 39, wherein applying the vacuum causes the second sheet to be drawn into an inlet well positioned beneath the inlet, the inlet well forming a convex surface with respect to the conforming surface.

41. The method of claim 40, wherein the inlet well guides the microfluidic droplet to a predetermined region as the microfluidic droplet is introduced into the gap.

42. The method of claim 40, wherein the inlet well guides the microfluidic droplet to a droplet removal region in the cartridge.

43. The method of claim 39, wherein introducing the microfluidic droplet includes adding a surfactant to the microfluidic droplet.

44. The method of claim 39, wherein selectively reducing the gap moves the microfluidic droplet to a region of the base unit adjacent to a heating unit.

45. A non-transitory computer readable storage medium comprising instructions that, when executed by one or more processors of a device, cause the device to perform operations comprising:attach a cartridge onto a base unit, wherein:the cartridge includes a first sheet, a second sheet, and a gap therebetween; andthe base unit includes a conforming surface configured to receive the cartridge;apply a vacuum through the conforming surface of a base unit causing the second sheet to conform to the shape of the conforming surface;receive a microfluidic droplet though an inlet of the cartridge and into the gap of the cartridge; andselectively reduce, by a control unit, the gap in one or more regions adjacent to the microfluidic droplet so as to move the microfluidic droplet.