BACKGROUND

The need to load and store excessive fluid volumes on disposable microfluidic cartridges can be problematic due to, for example, limited space availability. On the other hand, storing fluids, such as reagents, away from the fluidic region of interest (e.g., a flow cell) can lead to the problem of excessive pump times for moving fluids from the storage location to the fluidic region of interest and presents high flush factor requirements to replace fluids at the region of interest.

Many microfluidic systems with onboard fluid storage house the fluids away from the fluidic region of interest and have some form of valving, whether it be a rotary valve or an array of pinch valves, which adds further distance between the fluids and where they are used on the cartridge. These distances, known as swept volumes, are used to calculate the total volume delivered for a specific chemistry step and thus the further the fluids are stored away from the fluidic region of interest, the more volume is involved per step. For chemistries with many repetitive steps, these used volumes get multiplied, for example, by values ranging from 300 to 600 and thus the total swept volume can have a significant effect on the total fluid volumes required. As fluid volume requirements are the primary driver for microfluidic device size, large swept volumes greatly limit device size reduction potential.

Some microfluidic cartridge devices use fluid volumes that are larger than the volumes need for the onboard chemistry. Such high volumes may be used, for example, for flushing to exchange fluids through shared common lines and at the target surface. Such high fluid volume needs may become even more acute when long, cyclical assays are to be automated. Long fluid lines used to transport fluids that are stored remotely from the fluidic region of interest can present hard to wash locations within a microfluidic pathway, such as ninety degree turns. In addition, the walls of the fluid line may be hard to wash due to no-slip boundary condition in laminar flow environments.

In standard microfluidic systems, priming may be performed in channels located at the fluid storage region away from the fluidic region of interest with channels feeding into a shared switching valve which enables on-demand fluid selection. A long shared line, or common line, then transports all of the fluids to the fluidic region of interest where fluidic exchange occurs. In such standard systems, before a different fluid is to be provided at the fluidic region of interest, the previous fluid may be flushed out to preserve the correct chemical composition of the new fluid or to avoid hindrance by opposing chemistries (i.e., avoid cross-contamination).

The volume of fluid needed to flush a common line prior to addition of a different fluid will depend on the length of the common line and is known as the “swept volume.” A “flush factor” may be thought of as a multiplier to be applied to the total swept volume, or volume of channels shared by the fluids. For example, if a swept line is 10 μL in volume, a flush factor of 3 would require 30 μL of a fluid to be pulled through the system to generate proper exchange. For cyclical chemistry assays with many repetitions, minimizing individual fluid transfer volumes has a significant impact on the overall volumes to be stored on the fluidic devices. By minimizing the store volumes, cartridge footprints can be reduced and money is saved on a per run basis due to a reduction in materials and fluids. In some instances, total run time may be reduced due to shorter pumping operation times.

SUMMARY

The following presents a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview of the claimed subject matter. It is intended to neither identify key or critical elements of the claimed subject matter nor delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

Aspects of the disclosure encompass an apparatus comprising two or more fluid prime channels connected to a fluid inlet of a fluidic device, a flow control valve operatively associated with each fluid prime channel to control flow between the associated fluid prime channel and the fluid inlet, one or more outlet channels connected to a fluid outlet of the fluidic device, and a flow control valve operatively associated with each outlet channel to control flow between the fluid outlet and the associated outlet channel.

Aspects of the disclosure encompass a method comprising caching a different fluid in each of two or more fluid prime channels connected to a fluid inlet of a fluidic device, wherein a flow control valve operatively associated with each fluid prime channel controls flow between the associated fluid prime channel and the fluid inlet, moving at least a portion of a first fluid in a first of the two or more fluid prime channels into the fluid inlet, moving the first fluid through a fluid outlet of the fluidic device into an outlet channel connected to the fluid outlet, wherein a flow control valve operatively associated with the outlet channel controls flow between the fluid outlet and the outlet channel, moving at least a portion of a second fluid in a second of the two or more fluid prime channels through a shared fluid prime channel connecting the first and second fluid prime channels to the fluid inlet to flush the shared fluid prime channel, and moving at least a portion of the second fluid in the second fluid prime channel into the fluid inlet.

Aspects of the disclosure encompass an apparatus comprising a plate that is rotatable about an axis of rotation that is orthogonal to a surface of the plate and a plurality of fluid compartments disposed on the plate, each compartment having a fluid exit port formed through the plate, wherein the fluid exit ports of the plurality of fluid compartments are disposed at a common radial distance from the axis of rotation, and wherein each exit port is positioned to align with a fluid inlet of a fluidic device as the plate rotates about the axis of rotation.

Other features and characteristics of the subject matter of this disclosure, as well as the methods of operation, functions of related elements of structure and the combination of parts, and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.

