An electrowetting system is disclosed. The system includes electrodes configured to manipulate droplets of fluid in a microfluidic space. Each electrode is coupled to circuitry operative to selectively apply a driving voltage to the electrode. The system includes a dielectric stack including a first dielectric pair comprising a first layer having a first dielectric constant and a second layer having a second dielectric constant. The second dielectric constant is larger than the first dielectric constant. The dielectric stack includes a second dielectric pair comprising a third layer having a third dielectric constant and a fourth layer having a fourth dielectric constant. The fourth dielectric constant is larger than the third dielectric constant. A ratio of a thickness of the fourth layer to a thickness of the third layer (T.sub.4:T.sub.3) is in the range from about 2:1 to about 8:1. The second dielectric pair is thinner than the first dielectric pair.

Described herein are digital microfluidic (DMF) devices and corresponding methods for managing reagent solution evaporation during a reaction. Reactions on the DMF devices described here are performed in an air or gas matrix. The DMF devices include a means for performing reactions at different temperatures. To address the issue of evaporation of the reaction droplet especially when the reaction is performed at higher temperatures, a means for introducing a replenishing droplet has been incorporated into the DMF device. A replenishing droplet is introduced every time when it has been determined that the reaction droplet has fallen below a threshold volume. Detection and monitoring of the reaction droplet may be through visual, optical, fluorescence, colorimetric, and/or electrical means.

A digital microfluidic device, comprising a bottom plate and a top plate. The bottom plate comprises a bottom electrode array comprising a plurality of digital microfluidic propulsion electrodes. The top plate comprises a segmented top electrode array comprising a plurality of separately voltage addressable top electrode segments. Each top electrode segment and at least two of the propulsion electrodes of the bottom electrode array form a zone within the device. A controller is operatively coupled to the top electrode array and to the bottom electrode array and is configured to provide propulsion voltages between the top plate segment and the bottom plate propulsion electrodes of at least one of the zones. The top plate and the bottom plate are provided in a spaced relationship defining a microfluidic region therebetween.

A microfluidic device comprising: (a) a plate comprising a substrate, a plurality of electrodes, and a first layer of hydrophobic material applied over the plurality of electrodes; (b) a processing unit operably programmed to perform a method of pinning an aqueous droplet within the microfluidic device; and (c) a controller operably connected to a power source, the processing unit, and the plurality of electrodes. The method of pinning an aqueous droplet comprises: applying an electric field of a first polarity to an aqueous droplet located on the surface of the layer of hydrophobic material and having a first contact angle, to cause the droplet to maintain a second contact angle in the absence of the electric field, wherein the aqueous droplet contains a surfactant and the second contact angle is less than the first contact angle.

The disclosure provides a method of manipulating droplets in an electro-wetting on dielectric (EWOD) device. Electro-wetting electrodes of the EWOD device are selectively actuated to: cause first and second droplets in a fluid medium in the fluid chamber of the EWOD device to contact each other to form a droplet interface bilayer, the first droplet containing fluid of a first composition including a first solute species and the second droplet containing fluid of a second composition different to the first composition, maintain the first and second droplets contacting each other to maintain the droplet interface bilayer and thereby allow the first solute species to pass from the first droplet to the second droplet via the DIB; and cause the first droplet to separate from the second droplet. This method aspect results in transfer of solute from the first droplet to the second droplet. This provides a convenient way of altering the concentration of a particular component or components in a fluid droplet within an EWOD device. This allows, for example, an undesired solute species to be extracted from a reaction droplet or the undesired solute species to be diluted in the reaction droplet before the droplet undergoes further reaction steps.

A driving circuit, a driving method and a microfluidic substrate are provided. The driving circuit includes a first switching unit, a second switching unit, a reset unit, a first capacitor, and a second capacitor. In a first stage of a driving process of the driving circuit, the first switching unit is turned on, a first voltage signal is transmitted to a first node, the second switching unit is turned on, a second voltage signal is input to an output terminal of the driving circuit, and the driving circuit outputs an AC signal. In a second stage of the driving process, the first switching unit is turned off, the valid signal output by the second scan signal terminal controls the reset unit to be turned on, a third voltage signal is input to the output terminal of the driving circuit for reset, and the driving circuit outputs a DC signal.

A digital microfluidic (DMF) system based on an electrowetting-on-dielectric mechanism includes a substrate, and at least one dielectric layer comprising diamond-like carbon over the substrate. The DMF system also includes a plurality of electrodes connected to the dielectric layer. A voltage source is selectively couplable to different electrodes of the plurality of electrodes.

A microfluidic device includes first and second substrate structures. The first substrate structure has a first substrate surface configured to receive one or more droplets. A plurality of electrodes configured to apply an electric field to the droplets. The second substrate structure has a second substrate surface facing the first substrate surface and spaced apart from the first substrate surface to form a fluid channel. The microfluidic device has a first heating element adjacent to the first substrate structure and disposed on an opposite side of the first substrate surface, and a second heating element adjacent to the second substrate structure and disposed on an opposite side of the second substrate surface. The microfluidic device further includes one or more temperature sensors disposed adjacent to the fluid channel between the first substrate structure and the second substrate structure.

A microfluidic device includes: first substrate, microfluidic channel layer, and second substrate; the first substrate includes light source layer including a plurality of light source structures, the light source structure includes first electrode, second electrode, and an electroluminescence module, and when being turned on, emits light passing through the microfluidic channel layer and irradiating the second substrate; the second substrate includes photoelectric detection layer including a plurality of photoelectric detection structures and driving electrode layer including a plurality of driving electrodes and a plurality of driving circuits, the photoelectric detection structure includes third electrode, fourth electrode, and photoelectric conversion module arranged therebetween, and when being turned on, generates an electrical signal according to an incident light signal; the driving circuit is configured to apply a voltage to each driving electrode such that a droplet moves in a microfluidic channel of the microfluidic channel layer.

Droplet interfaces are formed between droplets in an electro-wetting device comprising an array of actuation electrodes. Actuation signals are applied to selected actuation electrodes to place the droplets into an energised state in which the shape of the droplets is modified compared to a shape of the droplets in a lower energy state and to bring the two droplets into proximity. The actuation signals are then changed to lower the energy of the droplets into the lower energy state so that the droplets relax into the gap and the two droplets contact each other thereby forming a droplet interface. The use of sensing electrodes in the device permit electrical current measurements across the droplet interface. The sensing electrodes can be used for either (i) applying a reference signal during droplet actuation or (ii) recording electrical current measurements.