Methods described herein provide a way to reduce or eliminate drag and adhesion of a substance flowing over a surface by creating a vapor cushion via evaporation of a phase-changing material of or on the surface or encapsulated within textures of the surface. The vapor cushion causes the flowing substance to be suspended over the surface, greatly reducing friction, drag, and adhesion between the flowing substance and the surface. The temperature of the flowing substance is above the sublimation point and/or melting point of the phase-changing material. The phase-changing material undergoes a phase change (evaporation or sublimation) upon contact with the flowing substance due to local heat transfer from the flowing substance to the material, generating a vapor cushion between the solid or liquid material and the flowing substance.

Methods and apparatus for manufacturing a microfluidic arrangement are disclosed. In one arrangement a continuous body of a first liquid is provided in direct contact with a substrate. A second liquid is provided in direct contact with the first liquid and covering the first liquid. The first liquid is in direct contact exclusively with the second liquid and the substrate. The second liquid is forced through the first liquid and into contact with the substrate in selected regions of the substrate in order to divide the continuous body of the first liquid into a plurality of sub-bodies of the first liquid that are separated from each other by the second liquid. The first liquid is immiscible with the second liquid. Surface tension stably holds the plurality of sub-bodies of the first liquid separated from each other by the second liquid.

Methods and apparatus for controlling flow in a microfluidic arrangement are disclosed. In one arrangement, a microfluidic arrangement comprises a first liquid held predominantly by surface tension in a shape defining a microfluidic pattern on a surface of a substrate. The microfluidic pattern comprises at least an elongate conduit and a first reservoir. A second liquid is in direct contact with the first liquid and covers the microfluidic pattern. A flow of liquid is driven through the elongate conduit into the first reservoir. The microfluidic pattern and the depth and density of the second liquid are such that the first reservoir grows in volume during the flow of liquid into the first reservoir, without either of the size and shape of an area of contact between the first reservoir and the substrate changing, until an upper portion of the first reservoir detaches from a lower portion of the first reservoir due to buoyancy and rises upwards through the second liquid, thereby allowing the first reservoir to continue to receive liquid from the flow of liquid without any change in the size and shape of the area of contact between the first reservoir and the substrate.

Techniques are disclosed for producing a drop of a viscoelastic fluid. A separation volume of viscoelastic fluid that is to form a drop from a larger remnant volume of viscoelastic fluid is moved from through an interface and into a cross-channel. Movement subjects the viscoelastic fluid to shear that may cause a reduction in viscosity. Movement of the viscoelastic fluid is then reduced or stopped (i.e., the rate at which shear is applied is reduced), such that the viscosity of the viscoelastic fluid may increase as the viscoelastic fluid experiences relaxation. The separation volume of viscoelastic fluid is then moved down the cross-channel in a first direction by the flow of an immiscible fluid, which separates the separation volume from a remnant volume. The separation volume may then be dispensed from the cross-channel as a drop.

A microfluidic system includes a matrix structure having a plurality of wells, each of the wells being accessible via at least one microfluidic path connectable via an interface to at least one droplet input for receiving one or more sets of droplets from one or more droplet sources, wherein a droplet enters a well based on one or more of: buoyancy, gravity, hydrodynamic force, and/or mechanical capturing, and wherein contents of a particular well are determinable based on a position of the particular well in the matrix structure and on inputs to the matrix structure. Methods using the matrix structure.

In alternative embodiments, provided are high-throughput, multiplexed systems or methods for detecting a chemical, biological, a physiological or a pathological analyte, or a single molecule or a single cell in droplets using the floating droplet array system, whereby droplets are trapped in an array of trapping structures. In alternative embodiments, high-throughput, multiplexed systems as provided herein are integrated with portable imaging systems such as CCD, CMOS, digital camera, or cell phone-based imaging.

Embodiments disclosed herein are directed to microfluidic devices that allow for scalable on-chip screening of combinatorial libraries and methods of use thereof. Droplets comprising individual molecular species to be screened are loaded onto the microfluidic device. The droplets are labeled by methods known in the art, including but not limited to barcoding, such that the molecular species in each droplet can be uniquely identified. The device randomly sorts the droplets into individual microwells of an array of microwells designed to hold a certain number of individual droplets in order to derive combinations of the various molecular species. The paired droplets are then merged in parallel to form merged droplets in each microwell, thereby avoiding issues associated with single stream merging. Each microwell is then scanned, e.g., using microscopy, such as high content imaging microscopy, to detect the optical labels, thereby identifying the combination of molecular species in each microwell.

A nucleic amplifier is provided to reduce an amplification efficiency drop even with a short cycle time. In the nucleic amplifier, the denaturation phase of moving and retaining a liquid droplet in a first region of a container heated to a denaturation temperature of a target nucleic acid, and the synthesis phase of moving and retaining the liquid droplet in a second region of the container different from the first region are repeated in multiple cycles. The liquid droplet contains a fluorescently labeled probe. The fluorescently labeled probe contains a minor groove binder molecule.

A separation device, system and associated method are provided herein for separation of particulates form a base fluid. The separation device comprises a first microchannel comprising a fluid inlet and a mesofluidic collection chamber. The mesofluidic collection chamber has a first side and a second side, wherein the mesofluidic collection chamber is operatively coupled to the first microchannel on the first side, and wherein the mesofluidic collection chamber comprises a first fluid outlet at the second side, such that the fluid inlet, first microchannel, and first fluid outlet are in fluidic communication via the mesofluidic collection chamber.

In an embodiment, the present disclosure pertains to a droplet system, apparatus, or fluid sample testing system to accomplish high-precision and high-efficiency droplet manipulation (e.g., greater than 99% platform operation efficiency). In some embodiments, the droplet system, apparatus, or fluid sample testing system includes at least one microfluidic channel or chamber and at least one interdigitated electrode (IDE) that can create a localized electric field below and/or within at least one fluidic channel or chamber. In some embodiments, this allows size-specific and/or size-dependent droplet manipulation.