Pressure regulated continuously variable volume container for fluid delivery

Abstract

A fluid handling and delivery system useful in generating a fluid stream in the flow path of microfluidic device.

Description

I. BACKGROUND [0001] A pressure regulated continuously variable volume container for the handling and delivery of fluids. Specifically, a pressure regulated variable volume container useful in generating a fluid stream in the flow path of various types of microfluidic devices such as flow cytometers or liquid chromatographs. [0002] Flow cytometry, liquid chromatography, and other microfluidic devices are prominent tools used in basic and applied research and in commercial manufacturing processes. These microfluidic systems are routinely used to analyze, separate, isolate, or purify biological particles, such as cells, organelles, chromosomes, deoxyribonucleic acids (DNA), ribonucleic acids (RNA), DNA fragments, RNA fragments, proteins, protein fragments, peptides, oligonucleotides, or the like. [0003] Specifically with respect to applications in flow cytometry or the utilization of flow sort devices, biological particles, such as cells (which may be modified with one or a plurality ...

AI Technical Summary

Benefits of technology

[0027] Accordingly, a broad object of the invention can be to eliminate exposure of fluid(s) being delivered to the flow path of a microfluidic device or chromatography systems to external sources of contamination. One aspect of this object of the invention can be to isolate the fluids being delivered to the flow path of a microfluidic device from moving toward equilibrium with atmospheric gases, mixtures of gases, or partial pressures of gases whether at atmospheric pressure or at greater than atmospheric pressures. A second aspect of this object of the invention can be to isolate the fluids being delivered to the flow path of a microfluidic device from exposure to non-biological materials or surfaces, such as, pump surfaces, dust, cleaning compositions, or the like; or to biological substances or surfaces which may introduce pathogens, bacteria, viruses, spores, cells, proteins, nucleic acids, tissues, blood, semen, urine, feces, or the like. A third aspect of this object of the invention can be to maintain a sterile fluid to be delivered to the flow path of a microfluidic device.

[0030] Another broad object of the invention can be to establish or maintain a desired concentration of a dissolved gas or gases in the fluid delivered in the flow path of a microfluidic device such that particles (whether biological or non-biological) are exposed to the concentration or level of gas(es) necessary or desired; or exposure of particles to certain unwanted gases, mixtures of gases, or partial pressures of gases, increased water content, or the like, can be avoided.

[0034] Another broad object of the invention can be to provide fluids and methods of delivering fluids to the flow paths of microfluidic devices which are compatible with the isolation or purification of cells or other particles or substances for reintroduction into a human or animal. There are a significant number of concerns raised with respect to the prevention of transmission of infection or disease when cells, particles or substances are isolated by microfluidic devices. Infectious particles or other agents can vary in size from prions which can be a few tens of nanometers, to virus particles which may be a few hundreds of nanometers, to yeasts, fungus, molds and bacteria which can be several hundreds of nanometers to many micrometers in size. Once a sample of cells, particles or other substance is contaminated with such infectious particles, it can be very difficult to remove them. In some cases, agents such as preservatives or antibiotics are acceptable, but in most products being used in animals and humans, the governmental regulations requires use of production methods which can be validated to produce biological cells, particles, substances or chemicals free of all such adventitious infectious particles or agents. The instant invention facilitates the preparation, shipment, storage, handling, and use of validated sterile solutions free of adventitious particles or agents, which can be delivered under pressure to flow cytometer, flow cell, or other microfluidic devices or chromatographic systems to generate cells, particles or other substances free of infectious or other unwanted agents.

Problems solved by technology

Any inaccuracy in the preparation of such fluids can lead to significant loss of chromatograph operating time or loss in whole or in part of the unpurified mixed particle(s) or population(s) of particles or of the purified individual particle(s) or subpopulation(s) of particles of interest.

Nonetheless, significant problems remain unresolved with regard to establishing and maintaining consistency in the preparation, handling, and delivery of fluids to and in the conduits of such microfluidic devices.

A significant problem with conventional delivery of fluids to microfluidic devices can be contamination of the fluid.

In this way, the surfaces of the pump body can become a source of contamination to the subsequent volume of fluid transferred through the pump body.

However, peristaltic pumps have disadvantages in that they may not build very high pressures, may tend to create oscillating hydrostatic pressure variations, may be expensive to build and maintain, and recurring peristalsis of the conformable conduit can cause progressive deformation or degradation of the conduit material which can shed, bleed, or leach into the fluid.

Another significant problem with conventional delivery of fluids to microfluidic devices can be the use of a gas or mixtures of gases, such as air, argon, nitrogen, helium, or the like, to pressurize the head space of a fluid reservoir to initiate and maintain a fluid stream in the conduits of the microfluidic device.

Use of pressurized gas(es) or atmospheric gas pressure in contact with fluid in the reservoir can result in bubble formation in the fluid paths of the device.

Since microfluidic devices have small diameter flow paths and the biological particles entrained in the fluid stream are also of small size, even very small or fine bubbles formed in the flow path can affect volume and laminar flow of the fluid within the flow paths, can cause failure of certain types of pumps, and can result in analytical errors.

Even bubbles invisible to the naked eye can be problematic with respect to the proper performance of a microfluidic device.

When pressurized gas enters the flow path of a microfluidic device directly, the bubbles can be much larger and in certain circumstances can interrupt of the flow of fluid all together, alter flow characteristics, or remain located in the flow path of the microfluidic device.

If the microfluidic device or flow path is not disposable, a significant amount of time may be needed to dislodge or flush unwanted bubbles from the flow path.

Another problem related to the use of pressurized gas in contact with liquids to generate a fluid stream in microfluidic devices can be an increased concentration of oxygen in solution.

High concentrations of dissolved oxygen may be generated by equilibration of the sheath fluid with pressurized gases containing oxygen and its use may result in detrimentally high metabolic rates in sperm cells during flow analysis or flow sort processes.

A similar problem with the use of atmospheric gases or pressurized gases in contact with fluids to generate a fluid stream can be increased amounts of water introduced into anhydrous solvents or other water sensitive fluids used within microfluidic devices.

Another similar problem with the use of atmospheric gases or pressurized gases in contact with fluids to generate a fluid stream can be reaction of the certain gases with the fluid or the particles entrained in the fluid.

Another significant problem with conventional preparation of fluids for use with microfluidic devices or chromatographic systems can be that the available water quality or chemical solvent quality may be unacceptably low from which to make standardized solutions for certain applications.

While there are numerous and varied methods to increase water quality, the cost of use may be unacceptably high when the source water contains a certain level of one or a plurality of materials, substances, or pathogens.

Neas et al. does not, however, address the problem of establishing a pressurized fluid stream in the flow path of any microfluidic devices such as a flow cytometer, liquid chromatograph, or the like.

Another significant problem with conventional delivery of fluids to microfluidic devices can be cleanup, disposal of unused amounts of fluid, and sterilization of fluid reservoirs.

The sheath fluid tanks or reservoirs typically contain between about five and about ten liters of sheath fluid, and if a procedure is interrupted or finished, it is often inconvenient to save the unused sheath fluid in the sheath fluid reservoir for use in the same procedure at a later date, because the sheath fluid tank may be needed for other procedures, or the sheath fluid may support the growth of microflora or microfauna, if stored.

With respect to certain fluids, interaction with atmosphere can be detrimental to the stability or consistency of the fluid.

A disadvantage of the small pressurized containers is that there are a limited number of acceptable propellants which are both inert to reaction with contained fluid(s), and yet benign to the environment.

In addition to the problems above-discussed with respect to interaction of gas with the fluids, there are additional disadvantages related to the safety of cleaning large containers of the remaining fluids and the disposal of the remaining fluids.

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