Generating binary states using a microfluidic channel

Methods and devices for using one or more fluidic channels for generating binary states are described. In particular, the present teachings relate to incorporating such fluidic channels into devices that use the generated binary states in various applications.

FIELD

The present teachings relate to using one or more microfluidic channels for generating binary states. In particular, the present teachings relate to incorporating such microfluidic channels into devices that use the binary states in various applications.

DESCRIPTION OF RELATED ART

Controlling the flow of fluids in microfluidic channels presents many challenges, especially when the fluids have low Reynolds numbers and the control is implemented upon continuous flowing liquids. One of the challenges lies in the difficulty of scaling down conventional flow control mechanisms such as valves, pumps, switches and mixers for use in controlling fluid flow inside microfluidic channels.

In one prior art solution, in addition to a first network of fluid-carrying channels, a separate network of channels is used to transport compressed air for use in operating valves and pumps. Understandably, such a separate network of channels not only involves additional internal structures inside a device in which the fluid-carrying channels are located, but also necessitates the use of additional structures external to the device. Such external structures may include transport structures for transporting the compressed air; interface structures for coupling the compressed air into the device; and control mechanisms for selectively modifying the air flow for activating control elements such as valves and pumps. The control mechanisms not only tend to be complex and bulky but also provide a less than desired level of accuracy in controlling fluid flow inside the fluid-carrying channels.

In an alternative approach, rather than using continuous flow techniques, a droplet-based approach is used wherein nanoliter to picoliter sized droplets of a fluid are introduced into a microfluidic channel, either individually or as a mixture along with one or more other fluids. One shortcoming associated with this alternative approach is that it is difficult to detect and control individual droplets for ensuring that a correct amount of fluid is being introduced into the microfluidic channel, even when external timers are used for controlling the introduction of the droplets into the microfluidic channel. Another shortcoming may be encountered when the droplet is in the form of a gas bubble, for example. In this case, the gas bubble may tend to disperse, escape, or dissolve, thereby rendering the delivery of the gas bubble through the microfluidic channel an uncertain and imprecise process. Additionally, a gas bubble is limited in its ability to transport usable materials, like chemicals or proteins, within a microfluidic device.

It is accordingly desirable to provide an arrangement that not only provides for precise fluid control, but also permits two fluids to be transported separately without intermixing, while accommodating flow control techniques and the generation of information in the form of digital data.

SUMMARY

According to a first aspect of the present disclosure, a fluidic device for generating binary states is provided. The device includes a first fluidic channel; and an electrode system that is arranged to provide a voltage potential that traverses at least a portion of the first fluidic channel. The device also includes a first fluid delivery system for introducing into the at least a portion of the first fluidic channel, a first fluid at a first instant in time and a second fluid at a second instant in time, wherein the first and the second instants in time correspond to a first binary state and a second binary state characterized by a first voltage differential and a second voltage differential respectively across the at least a portion of the first fluidic channel as a result of the first and second fluids being present in the at least a portion of the first fluidic channel at the first and the second instants in time.

According to a second aspect of the present disclosure, a method of generating binary states is provided. The method includes a first step of applying a voltage potential that traverses at least a portion of a first fluidic channel; and further includes a second step of positioning one of a first fluid or a second fluid inside the at least a portion of the first fluidic channel for modifying the voltage potential on the basis of at least one of a first dielectric constant or a first conductivity associated with the first fluid and at least one of a second dielectric constant or a second conductivity associated with the second fluid.

According to a third aspect of the present disclosure, a fluidic system for generating binary states is provided. The fluidic system includes a first fluidic control channel containing a first fluid through which is transported at least a first droplet comprising a second fluid; and further includes an actuator system comprising a toggle element that is settable to one of a first physical condition or a second physical condition upon subjecting the toggle element to a corresponding one of a first voltage potential or a second voltage potential that is generated as a result of the first droplet being located at one of a first position or a second position in the first fluid.

Further aspects of the disclosure are shown in the specification, drawings and claims of the present application.

DETAILED DESCRIPTION

Throughout this description, embodiments and variations are described for the purpose of illustrating uses and implementations of the inventive concept. The illustrative description should be understood as presenting examples of the inventive concept, rather than as limiting the scope of the concept as disclosed herein. For example, it will be understood that terminology such as, for example, voltage potential, voltage drop, voltage condition, voltage differential, nodes, terminals, circuits, devices, systems, and coupling are used herein as a matter of convenience for description purposes and should not be interpreted literally in a narrowing sense. For example, a voltage potential may be alternatively referred to herein as a voltage differential, or a voltage drop. A person of ordinary skill in the art will understand that these terms may be used interchangeably and as such must be interpreted accordingly. It will be also be understood that the drawings use certain symbols and interconnections that must be interpreted broadly as can be normally understood by persons of ordinary skill in the art. As one example, of such interpretation, the fluidic channels are shown to include channel walls. However, one of ordinary skill in the art will understand that fluidic channels are often created as voids or cavities in other materials and as such do not have a wall but rather may have one or more internal surfaces formed as a result of the void or cavity. Similarly, a capacitor or a dielectric element may be an integral part of a semiconductor layer inside an integrated circuit and formed using semiconductor fabrication techniques, or could be an integrated component of the microfluidic device, for example. It will be further understood that various words herein such as the word “droplet” encompasses various volumes of liquids such as a drop, a cluster of drops, a continuous flow, or an agglomerate; the phrase “fluidic channel” encompasses various sizes, such as a nanofluidic channel, a microfluidic channel and a channel of significantly larger size; the word “NOT” may be used interchangeably with “INVERTER”; and the word “voltage” encompasses voltages of various amplitudes and polarities. Specifically, in various figures the voltage labels indicate “0” V and “V” volts. However, in various embodiments, the voltage labels may be replaced with “−V” and “+V” wherein a proper usage of an appropriate voltage differential is more effective than absolute voltage values.

Attention is now drawn toFIG. 1, which shows a fluidic system100having a fluidic control channel110that is used for controlling an actuator system105. Voltage source125is used to supply to electrodes115and120, a voltage “V” of a suitable amplitude and polarity. The application of this voltage “V” results in a first voltage drop Δv1across actuator system105and a second voltage drop Δv2across fluidic control channel110. Fluidic control channel110is configured to generate binary states, in a process that will be described below in further detail using other figures. In a first binary state, the second voltage drop Δv2takes on a first amplitude, while in a second binary state, the second voltage drop Δv2takes on a different amplitude. This variation in amplitude in second voltage drop Δv2results in corresponding changes in the amplitude of first voltage drop Δv1, in order to satisfy the condition V=Δv1+Δv2. The variation in amplitude in first voltage drop Δv1is used to actuate a toggle element (not shown) associated with actuator system105. The actuation can then be used to control additional elements (not shown) that may be coupled to actuator system105.

However, it will be understood that in general, fluidic control channel110may be used as a stand-alone element for generating binary states that can be exploited for a variety of uses. Such embodiments may not necessarily include actuator system105. For example, actuator system105may be replaced by a different element that carries out one or more of a measuring, a computing, or an analytical function.

FIG. 2shows one example embodiment of a fluidic system200wherein the binary states generated in microfluidic control channel110are used for controlling the flow of an electro-rheological fluid106(toggle element) in a second microfluidic channel105(actuator system).

Microfluidic control channel110contains a first fluid111and a second fluid112, wherein the second fluid112is shown herein in the form of droplets112a,112band112c. The dielectric constant or conductivity associated with the first fluid111is typically selected to be different than the dielectric constant or conductivity associated with the second fluid112. Also, in various applications, the second fluid112is selected to be immiscible with the first fluid111so as to reduce or eliminate problems such as those associated with dispersion, solubility, and mobility. A few non-limiting examples of first fluid111includes fluids such as oil and water, while second fluid112includes oil and air (pure water, salt water etc).

One or both of the fluids are introduced into microfluidic control channel110by fluid delivery system145. Fluid delivery system145is merely a pictorial representation of various ways by which one or more fluids can be introduced into microfluidic control channel110. A few non-limiting examples include a real-time delivery system that introduces droplets112a,112b, and112cinto microfluidic control channel110in a periodic sequence, an intermittent sequence, or a one-time sequence, under control of a control mechanism (not shown). The control mechanism may be a manual control operated by a human being, or may be an electronic control. In certain embodiments, once introduced into microfluidic control channel110, one or more of droplets112a,112b, and112cmay be further restricted to remain within the microfluidic control channel110and manipulated from one position to a different position. Various flow-focusing techniques may be used to form droplets112a,112b, and112cinside microfluidic control channel110.

Also shown inFIG. 2, is an electrode system that includes a first electrode120and a second electrode115. Voltage source125provides voltage to the two electrodes whereby a voltage potential is set up along transverse axis135. Transverse axis135is substantially orthogonal to, and traverses microfluidic control channel110, creating an electromagnetic field between the first electrode120and the second electrode115. It will be understood that in an application wherein microfluidic control channel110is a stand-alone element, or is incorporated into a different configuration, first electrode120and second electrode115may be located immediate adjacent to, and straddling, microfluidic control channel110such that the voltage potential traverses microfluidic control channel110along transverse axis135. In effect, the voltage potential is arranged to intersect and be affected by at least one of first fluid111and second fluid112.

To understand this arrangement in further detail, each of control channel110and GER channel105may be visualized as two capacitors arranged such that the voltage provided by voltage source125is applied across the two capacitors as well as any object (separation barrier130) that may be located between the two capacitors. Each capacitor has certain properties such as a dielectric constant or an electrical conductivity that comes into play when the binary states are generated in microfluidic control channel110. To elaborate, the properties affect the amplitude of voltage drops across each element (Δv1and Δv2). In the case of microfluidic control channel110, the dielectric constant (or electrical conductivity) is a variable value that is dependent on the position of second fluid112vis-à-vis transverse axis135. Specifically, when second fluid112is located to intersect transverse axis135, the dielectric value of the capacitor (microfluidic control channel110) is different from when second fluid112is moved away and only first fluid111, which has a different dielectric constant, is present. The change in dielectric constant/electrical conductivity results in the two different voltage values that Δv2can take on. These two different voltage values are interpreted as the binary states, which may be used for various binary applications.

In terms of one such binary application, attention is now drawn to a microfluidic channel105arranged to be substantially parallel to microfluidic control channel110. For the sake of convenience, only a portion of microfluidic channel105is shown inFIG. 2. In some applications, this portion may constitute the entire length of the channel, while in other applications, microfluidic channel105extends beyond the area shown. In these other areas, microfluidic control channel110may no longer run parallel to microfluidic control channel110, and in certain instances may intersect microfluidic control channel110, say, for example, on a different layer, above or below a layer in which microfluidic control channel110is fabricated. It will also be understood that the parallel arrangement is merely one arrangement and in other arrangements, the relative orientation, dimensions, and separation distances of the two channels may be different as long as the capacitor effect between electrodes115and120are operative.

In the embodiment shown inFIG. 2, the first electrode120is located adjacent to microfluidic control channel110and the second electrode115is located adjacent to microfluidic channel105, thereby setting up a voltage potential that traverses both microfluidic channels. The voltage potential further traverses a separation barrier130that is provided in order to keep the fluid inside microfluidic control channel110from coming in direct or indirect contact (mixing, exposure etc) with a fluid contained inside microfluidic channel105. Separation barrier130may be formed of a variety of materials. In one embodiment, a polymer is used. The polymer may include other substances included, such as, for example, an electrically conductive element. A few non-limiting examples of electrically conductive elements include copper, silver, and gold. One example of a material used in separation barrier130is a polydimethylsiloxane (PDMS) compound, more specifically, in one embodiment, a PDMS compound with a silver micropowder additive. This material is referred to as AgPDMS. Another example of a material used in separation barrier130is poly(methyl methacrylate) (PMMA).

Various fluids can be transported via microfluidic channel105and various applications can be employed in various arrangements. These various applications include analytical applications, wherein the chemical, physical, biological and/or optical parameters of the fluid can be assessed; dispensing applications wherein a measurable quantity of a fluid can be delivered via microfluidic channel105; and control applications, wherein the fluid contained inside microfluidic channel105is used for controlling various elements such as a switch or a valve, for example. Channel105can also be a non-fluidic switch mechanism wherein no fluids are used at all.

In this particular example embodiment, as mentioned above, the fluid contained inside microfluidic channel105is an electrorheological fluid. Furthermore, in one specific case, the electrorheological fluid is a Giant Electrorheological (GER) fluid. As is known, electrorheological fluids react to appropriate electrical stimuli by changing physical characteristics. In the case of GER, the fluid transforms from a liquid state to a semi-solid or solid state depending upon the amplitude of a voltage potential applied across the GER fluid.

The GER fluid, or other fluid in microfluidic channel105, referred to hereafter as GER fluid106, is introduced into microfluidic channel105using a fluid delivery system140. Fluid delivery system140is merely a pictorial representation of various ways by which one or more fluids can be introduced into microfluidic channel105. A few non-limiting examples include a real-time delivery system that introduces the fluid into microfluidic channel105in a periodic sequence, an intermittent sequence, or a one-time sequence. The delivery may be controlled using a manual or an automatic control mechanism (not shown). When manual, the fluid is introduced into microfluidic channel105by a human being, in certain cases on a one-time basis. In certain embodiments, once introduced into microfluidic channel105, the fluid may be confined within microfluidic channel105in order to carry out a control action, for example. This aspect will be described below in more detail usingFIG. 9. In certain other embodiments, the fluid may be allowed to flow out of microfluidic channel105. In yet other embodiments, the flow of fluid either inside or out of microfluidic channel105may be used as a binary indicator, for example, in the implementation of Boolean logic circuits or devices. This aspect will be described below in more detail using several figures.

When the fluid inside microfluidic channel105is GER, the GER fluid106in area107transforms from a liquid state to a semi-solid or solid state depending upon the amplitude of the voltage potential present along transverse axis135. As explained above, this voltage potential can be set to one of two binary states by suitably positioning second fluid112inside microfluidic control channel110. Specifically, when droplet112bis located as shown (so as to intersect transverse axis135), the voltage differential across electrodes115and120rises above a threshold voltage potential, thereby leading to a transformation of GER fluid106from a liquid state to a semi-solid or solid state (depending upon the amplitude of the threshold voltage potential). The threshold voltage potential can be suitably selected based on the nature of individual applications. When area107is in a liquid state, GER fluid106is permitted to flow out of GER channel105as indicted by arrow108. On the other hand, when area107is in a solid state, the flow of GER fluid106out of GER channel105is blocked.

The electrical aspects are described below in further detail using other figures.

Attention is now drawn toFIG. 3, which shows a variation in the nature of the fluid flow inside microfluidic control channel110. In the embodiment shown inFIG. 3, second fluid112is introduced into microfluidic control channel110in a cluster form. Unlike the embodiment shown inFIG. 2, wherein the size of droplets112a,112band112care substantially large and are comparable to the diameter of microfluidic control channel110, each cluster in the embodiment shown inFIG. 3contains numerous droplets. Whether one droplet, or numerous droplets, the net effect of second fluid112being located between electrodes120and115is the resulting change in voltage differential between electrodes120and115, or in other words, the generation of one of the two binary states. First fluid111may be introduced into microfluidic control channel110in several different ways. In a first approach, first fluid111is introduced into microfluidic control channel110at a first instant in time and second fluid112is introduced at a later instant in time. The first and second instants can be repeated thereafter, or may be a one-time sequence. In a variation of this first approach, there may be one or more overlapping periods between the first and second instants when both fluids are simultaneously introduced into microfluidic control channel110. In a different approach, first fluid111is introduced into microfluidic control channel110in a repetitive first sequence, and a mixture of first fluid111and second fluid112is introduced into microfluidic control channel110in a repetitive second sequence that either overlaps portions of the first sequence or is interspersed with the first sequence. It will be understood that the fluid flow techniques described herein with reference to microfluidic control channel110may be applied to microfluidic channel105as well.

FIG. 4shows an equivalent electrical circuit representation of microfluidic control channel110arranged to interact with microfluidic channel105. In this particular interpretation, each microfluidic channel is represented as a capacitor, and it is assumed that second fluid112has a higher dielectric constant than first fluid111. The following set of equations is used to derive the amplitudes of the voltage differentials with and without droplet112baffecting the capacitance calculations. These calculations are merely a specific embodiment of the possible calculations, which could also include forms where the voltage to the far left is not grounded and instead some arbitrary V2is provided. The grounded configuration has been used here merely for simplification of the calculations presented herein for illustrative purposes.

Charge conservation dictates that
QC=QG

Additionally, the two constraints on the voltages are
V=VC+VG
VCCC=VGCG

Solving for VG leads to:

This equation can be further simplified by assuming that microfluidic control channel110and microfluidic channel105have similar dimensions, thereby leading to the areas and distances being identical. Under this assumption:

Finally, ∈Cis itself variable depending on the presence or absence of droplet112baffecting the voltage potential between electrodes115and120. Hence, VG=VG(x) wherein x=1 when droplet112bis present, and x=0 when droplet112bis absent. Assuming oil is the first fluid (the carrier through which the second fluid moves), water the second fluid, and GER is used as a toggle element that is settable to one of two physical conditions, then ∈G≈60, ∈H2O≈80, and ∈OIL≈2.

When droplet112bis not present and ∈C=∈OILthen

When droplet112bis present and ∈C=∈H2Othen

As can be understood, VG(1) and VG(0) can be suitably selected in relation to one or more threshold voltage values (potential values such that the GER solidifies) using the equations shown above for transforming GER fluid106from a liquid state to a solid state such that Vg(0)<Vthresh and Vg(1)>Vthresh.

FIG. 5is a table showing the various states of GER106when droplet112b(consisting of water) is either present or absent at an intersection of transverse axis135in microfluidic control channel110. The table shows that GER fluid106has an “off” state and an “on” state defined by rheological states (a liquid state or an anisotropic solid state, respectively). The configuration of these two states can be used to define a further output state of GER flow108(FIG. 2) that depends on the rheological state of GER in107. When the signal in107is “off” (i.e. the GER is in the liquid state), GER106can flow out GER channel105. When the signal in107is “on” (i.e. the GER is in the solid state), GER flow is impeded and cannot flow out of GER channel105. Thus, the state of GER in area107can be used to define a dependent state of GER flow out of GER channel105that depends immediately on the state of GER in area107, and indirectly on the presence or absence of droplet112bin the transverse intersection between120and130. The binary states of GER fluid106may be exploited for various purposes such as measuring or controlling the amount of GER fluid106flowing out of microfluidic channel105; for controlling other elements external to microfluidic channel105; and/or using the binary flow in binary devices or systems.

FIG. 6shows a first embodiment wherein the binary flow nature of a microfluidic channel510is controlled for implementing an OR logic functionality. In this embodiment, any one of two asserted input conditions produces an asserted output condition. In other words, this embodiment represents the OR logic equation generally used in Boolean algebra. The two logic inputs are provided via two microfluidic control channels505and515, while the output logic condition is provided by a pair of serially linked logic structures, which could include a microfluidic channel, such as microfluidic channel510(which will be referred to hereafter as GER channel510solely for convenience in description).

The location of a droplet506in the first microfluidic control channel505(intersecting voltage potential axis507) determines the liquid/solid state of region511of GER fluid106. Similarly, a location of a droplet516in the second microfluidic control channel515(intersecting voltage potential axis517) determines the liquid/solid state of region512of GER fluid106in GER channel510. As can be understood, when either region511or region512turns solid, the flow513of GER fluid106out of GER channel510is blocked. This blockage is interpreted as an asserted OR output condition. This interpretation can be generalized to any serially linked structures such that the assertion of either inputs505or515(or both) leads to a condition where flow in a third channel is blocked, whether by the solidification of GER fluid, or by the closing of a deformable membrane into another microfluidic structure.

FIG. 7shows a second embodiment wherein the binary flow nature of a microfluidic channel610is controlled for implementing an AND logic functionality. In this embodiment, an AND combination of two input conditions produces an asserted output condition. In other words, this embodiment represents the Boolean AND logic equation. The two logic inputs are provided via two microfluidic control channels605and615, while the output logic condition is provided by a microfluidic channel610(which will be referred to hereafter as GER channel610solely for convenience in description).

The location of a first droplet606in the first microfluidic control channel605(intersecting voltage potential axis607) as well as a similar position of a second droplet616in the second microfluidic control channel615(intersecting the same voltage potential axis607) determines the liquid/solid state of region611of GER fluid106. As can be understood, when either of first droplet606or the second droplet616is not positioned in the voltage potential axis607, region611of GER fluid106does not transition from a liquid to a solid state, thereby allowing GER fluid106to generate a flow612out of GER channel610. In contrast, when both the first and the second droplets are positioned appropriately, region611of GER fluid106transitions from a liquid to a solid state, thereby blocking the flow612out of GER channel610. This blockage is interpreted as an asserted AND output condition, and results from the electrical necessity of having voltage transmitted to607from the left electrode and to608from the right electrode before sufficient voltage potential can be established across611.

FIG. 8shows a third embodiment wherein the binary flow nature of a microfluidic channel715is controlled for implementing an INVERTER logic functionality. The logic input is provided via a microfluidic control channel705, while the output logic condition is provided by a microfluidic channel715, which will be referred to hereafter as GER channel715solely for convenience in description. The specific choice of use forFIG. 7is not limited to inversion and can be chosen to form a more general manifestation of the switch inFIG. 1or an INVERTER mechanism, depending on choices of voltages used.FIG. 7will be alternatively referred to as an inverter mechanism solely for convenience in description, description not limiting its service in other functional capacities.

The location of a droplet706in the microfluidic control channel705(intersecting voltage potential axis707) changes the liquid/solid state of region716of GER fluid106in GER channel715. As can be understood, when droplet706is moved away from a position that intersects the voltage potential axis707, region716of GER fluid106transitions from a solid state to a liquid state. In one embodiment, the solid state of region716is set as a default state, activated for default times when droplet706is not present. The default state is set using a capacitor system710, which is configured to couple a voltage potential (a default, quiescent state voltage) into separation barrier730. In an alternate embodiment, the voltage potential may be coupled directly into GER channel715and/or may be coupled into separation barrier730. Irrespective of the nature of the coupling, the voltage potential causes region716of GER fluid106to be set to a default state that is changed to an opposite state (inversion) by suitably positioning droplet706to either intersect or not intersect voltage potential axis707.

Capacitor system710may be implemented in a variety of ways. A few non-limiting examples include a capacitor that is fabricated directly on or inside a substrate (not shown) in which GER channel715is located. Semiconductor techniques for capacitor fabrication may be used. In another example implementation, a discrete capacitor or a portion of a discrete capacitor (a capacitor plate, for example) is mounted on the substrate. The adjacent location may be on the same layer of the substrate on which separation barrier730and/or GER channel715are located, or may be on a different layer, for example either above or below the layer on which separation barrier730and/or GER channel715are located. In a third example, the capacitor is built between layers of substrate.

The electrical behavior of the INVERTER configuration shown inFIG. 8will now be described in further detail.
Q1=Q2+Q3 (balance of charges inside the non-grounded portion730)
Q1=C1v1; Q2=C2v2; andQ3=CgνG

wherein “vx” represents the voltage potential across each of microfluidic control channel705, capacitor system710, and GER channel715respectively)
V1−v1=V2+v2=V3+νG(voltage in the central region must be the same regardless of which channel is chosen as a reference)

Solving for vg (and setting the capacitance CI of capacitor system710such that CI=f*CGwhere f is any selected ratio):

In one embodiment, the capacitance value of capacitor system710is similar to that of GER channel715(f≈1). The values for vG under this condition (and using values as described above in other equations) can be determined as follows:

By suitably configuring the various voltages, like an embodiment in which voltages are chosen such that V1=−V2=V and V3=0, the values for νG(0) and νG(1) are as follows:

The amplitude of voltage V is selected such that the solidification threshold of GER fluid106in GER channel715is crossed only when droplet706is absent, i.e. V/10<Vthresh<V/2. Droplet706may be positioned to intersect voltage potential axis707subsequently when the INVERTER action is desired.

In an alternate interpretation of the inverter mechanism, droplet706is an electrically conductive fluid, but the carrier fluid (the fluid present in channel705that contains droplet706) is electrically non-conductive. In this embodiment, capacitor C1can be set to be very large, such that the voltage in730approaches the value set by V2when droplet706is not present. When droplet706is present along axis707, then electrical current can pass through droplet706, and set the voltage of730to V1. Because conductive droplet706can physically allow charge to be added to730, its effect will dominate the polarization effect caused by the capacitor C1. If capacitor C1is set to be large enough, the electrical voltages in730will approach the result: V(730)=V2if no droplet706; V(730)=V1if droplet706.

FIG. 9shows GER channel105configured for a control functionality, specifically to activate an external element such as a switch or a valve. In the example configuration shown inFIG. 9, the external element is shown as a first element905located above GER channel105and a second element910that may be placed below GER channel105. These two positions are shown solely for purposes of describing a push-up and a push-down type of action. It will be understood that one or more of such external elements may be placed in various other locations and orientations with respect to GER channel105. Furthermore, it is not necessary that both element905and element910be employed. In certain applications only one of these two elements may be used, while in certain other applications, more than two elements may be controlled. Furthermore, it is not necessary that GER be used in channel105(in various forms); some general, unspecified control mechanism actuated by an electric signal could be used in an alternate capacity to activate possible push-up or push-down valves905.

In an embodiment utilizing GER fluid in105, when droplet112bis positioned in microfluidic control channel110as shown, area107in GER channel105transitions from a liquid state to a solid state. Upon occurrence of this solidification, additional GER fluid106that is forced into GER channel105by fluid delivery system140along path909is blocked thereby causing pressure between the Fluid Delivery System140and area107to experience a buildup of pressure. Due to the flexibility of the membranes at906, this will cause GER fluid106to move radially outwards. The direction indicated by arrow907may be used to expand surface906of GER channel105to expand and apply pressure against element905. This pressure is used to carry out a control operation, such as for example, a switch activation when element905is a switch. When element905is a channel carrying a fluid, the pressure may result in a constriction of a surface of the channel which can modulate the flow of fluid inside. GER fluid106expansion in the direction indicated by arrow908may be similarly used for controlling the other element910.

FIG. 10shows a universal logic device900incorporating microfluidic channels and a capacitor system in specific configurations can be implemented as logic an effective joining of inverter mechanisms into a structure exhibiting AND functionality (as inFIG. 7). Two inverter mechanisms can also be combined into a structure exhibiting OR functionality (as inFIG. 6). Such a universal logic device may be used in a variety of applications, including one that is referred to in the industry, as a lab-on-a-chip (LOC). Unlike traditional LOC devices, which include various external elements for control and monitoring purposes, universal logic device900incorporates numerous functionalities intrinsically, thereby providing logistic and performance advantages over traditional LOC devices.

Specifically, universal logic device900includes a GER channel7, a first microfluidic control channel5, a second microfluidic control channel6, an electrode system that includes electrodes1-4, and a pair of capacitor systems8and9. Each of the capacitor systems provides an INVERTER functionality to be implemented in universal logic device900, while the remaining elements enable universal logic device900to be configured for a variety of logic operations. Unlike traditional approaches wherein several NAND gates or NOR gates are combined together to implement even simple binary logic functions, the universal logic device900permits implementation of these same binary logic functions using a single logic gate mechanism. Like NAND and NOR logic, universal logic device900can also be combined together with other logic devices to enable further more complicated logic functions.

The voltages applied to the various electrodes1-4and the position of droplets inside microfluidic control channels5and6, determine which of sixteen possible logical operations can be implemented in universal logic device900. Of the four electrodes, two electrodes1and4(V1and V4) (in conjunction with an electrode connection area10if needed) are used for configuring the two control channels, while the two other electrodes2and3(V2and V3) are used for the capacitor system in order to implement INVERTER functionality. Capacitor systems8and9couple into separation barrier13, suitable voltages to set the GER fluid inside GER channel7to a default state. GER fluid is introduced into, and exits from, GER channel7via ports16and17. Similarly, fluid introduction and exit from microfluidic control channels5and6are carried out via ports14/15, and18/19respectively. Ports may also be interpreted as continuations of the microfluidic channels into other portions of a larger device, here unspecified.

The electrical behavior of universal logic device900will now be described using the simplified circuit diagramFIG. 10. Assuming that the INVERTER circuitry operates in the same fashion as described above, the voltage potential νGacross GER channel can be defined by the following expression:

The truth table of the various combinations and corresponding voltage amplitudes is shown inFIG. 12. The truth table can be used to configure universal logic device900for implementing at least sixteen logical conditions by manipulating the various voltage levels and the droplets in the control channels without a modification of the basic structure inside universal logic device900.

FIGS. 13 and 14provide a detailed diagram listing various voltages and input polarities that can be used for operating universal logic device900in the various logical modes. It will be understood that the listing is non-exhaustive in nature and several other modes may be applicable other than the one shown. The general guide to interpretingFIGS. 13 and 14is as follows: all polarities (+, −, 0, ++, −−) are relative and occur in the following order: (++, +, 0, −, −−) in order of voltage potential, representing for the purposes of the diagram the values of (2, 1, 0, −1, −2). A blank space represents an unconnected voltage terminal. The phrase “channel A” refers to microfluidic control channel5while “channel B” refers to microfluidic control channel6.

The idealized voltage potential across the activation mechanism can be determined as follows:

1) The potential difference across the activation mechanism is assumed to be the absolute value of the difference between the one active voltage in set {A} (i.e. V1, V2) and the one active voltage in set {B} (i.e. V3, V4).

2) An absolute value difference of greater than 2 is sufficient to activate the actuator mechanism or signal chosen for the particular application of the logic device

3) The active voltages are determined as follows:a) if neither channels A nor B are activated (i.e. both are in the fluidic “0” state), the active voltages are, by default {A}=V2and {B}=V3b) if channel A is set in the “1” state, then {A} takes the value of V1instead of V2c) if channel B is set in the “1” state, then {B} takes the value of V4instead of V3d) if both A and B are in the “1” state, then b and c still apply

4) The exception to the above rules occurs when a blank value (blank space) is involved. The blank space effectively indicates no voltage potential, and is therefore set by the nearest active value.a) V1or V4=blank value: the values of {A} or {B} are independent of the fluidic state in channels A or B, respectivelyb) V2or V3=blank valuei) If channels A or B (respectively) are active, then V2or V3are overridden according to the rules defined in item 3) above.ii) A=“0” and V2=blank value, then {A} takes the value of {B}iii) B=“0” and V3=blank value, then {B} takes the value of {A}iv) A=“0” and B=“0” and V2=blank value and V3=blank value. Then {A} and {B} are functionally set to 0.

5) The specific values displayed in the truth table are arbitrary provided that the correct absolute value is maintained when the above rules are applied.

FIG. 15shows various process steps associated with manufacturing a logic device incorporating one or more microfluidic channels. The steps can be broken up into two parts wherein a first part involves the development of a suitable mold, and a second part involves manufacturing a device using the mold. Typically, photolithographic techniques may be used for a number of steps in the manufacturing process. A non-exhaustive list of these steps is provided below.

Spin a negative photoresist (such as SU8, for example) on to a glass substrate (step50inFIG. 13). Expose and develop the negative photoresist in a suitable development process (steps51and52). Spin a positive photoresist (such as AZ4903) on top of the negative photoresist. This can be done multiple times so as to obtain a thickness of about 80 μm. The positive photoresist is developed (using a developer such as AZ400K:DI water=1:3 volume) to form a set of electrode cavities. The mold is then completed by applying surface polishing or sanding as needed (steps53-56).

The logic device can then be manufactured using the mold as described hereafter. The electrode material (AgPDMS, for example) is filled into the cavities of the mold (step57). Excess AgPDMS may be removed and the surface cleaned. The assembly is then baked in an oven at approximately 60 degrees for approximately 30 minutes to cure the AgPDMS. Pour a PDMS gel into the mold and bake in the oven at approximately 60 degrees for approximately 2+ hours to cure the PDMS. Peel the PDMS together with the AgPDMS electrodes from the glass substrate (step60). Using a half-bake method, seal the device onto a flat PDMS layer (step61). The sealed assembly is then baked on a hotplate at approximately 150 degrees for over 2 hours to finalize the manufacturing process.

All patents and publications mentioned in the specification may be indicative of the levels of skill of those skilled in the art to which the disclosure pertains. All references cited in this disclosure are incorporated by reference to the same extent as if each reference had been incorporated by reference in its entirety individually.

The examples set forth above are provided to give those of ordinary skill in the art a complete disclosure and description of how to make and use the embodiments of the enhancement methods for sampled and multiplexed image and video data of the disclosure, and are not intended to limit the scope of what the inventors regard as their disclosure. Modifications of the above-described modes for carrying out the disclosure may be used by persons of skill in the video art, and are intended to be within the scope of the following claims.