Two-stage flow system with reduced pulsation

Abstract

A system for generating a low-pulsating fluid flow includes: a first pressurized reservoir (106); a second pressurized reservoir (126); a fluid sensor (128) that generates a quantity signal in response to the amount of fluid in the second pressurized reservoir (126); a peristaltic fluid pump (118) for pumping fluid from the first pressurized reservoir (106) to the second pressurized reservoir (126); and a peristaltic air pump for pumping air between the first pressurized reservoir (106) and the second pressurized reservoir (126). The system is configured to modulate the operation of the peristaltic fluid pump (118) in response to the fluid volume signal generated by the fluid sensor (128) to maintain a predetermined amount of fluid in the second pressurized reservoir (126), and is configured to pump air between the first pressurized reservoir (106) and the second pressurized reservoir (126) to maintain the two pressurized reservoirs (106, 126) at substantially equal pressures, thereby reducing fluid pulsation. A corresponding method for generating low-pulsation fluid flow is also disclosed.

Description

Technical Field

[0001] The present disclosure relates to the field of fluid handling systems and to the field of pulsation-reduced fluid flows. Background Art

[0002] Various types of instruments, including medical research instruments, require a steady flow of fluid at a substantially constant pressure. Pumps that pump fluids typically produce a pulsating flow of the liquid, that is, the pressure of the flow pulsates due to the pulsating nature of the pump. Achieving a highly consistent and constant flow of fluid at a predetermined pressure and rate is difficult and expensive. Therefore, there has long been a need in the art for systems and methods for delivering a fluid flow with reduced pulsation. Summary of the invention

[0003] In order to meet the above-mentioned long-standing needs, the present disclosure provides, in one aspect, a method for generating a sheath flow for a flow cytometer, comprising: using a first peristaltic sheath pump to pump a sheath fluid into a first pressurized reservoir; sensing the amount of the sheath fluid in the first pressurized reservoir to generate a first sheath fluid amount signal; in response to the first sheath fluid amount signal, maintaining a predetermined amount of the sheath fluid in the first pressurized reservoir by pumping the sheath fluid into the first pressurized reservoir using the first peristaltic sheath pump; pumping the sheath fluid from the first pressurized reservoir to a second pressurized reservoir using a second peristaltic sheath pump; sensing the sheath fluid in the second pressurized reservoir; and to generate a second sheath fluid volume signal; in response to the second sheath fluid volume signal, pump the sheath fluid into the second pressurized reservoir by using the second peristaltic pump to maintain a predetermined amount of the sheath fluid in the second pressurized reservoir; supply air to the first pressurized reservoir by using an air pump to pressurize the first pressurized reservoir; pump air from the first pressurized reservoir to the second pressurized reservoir by using the peristaltic air pump to pressurize the air in the second reservoir to a predetermined air pressure; and maintain the predetermined air pressure in the second reservoir by pumping air into the second reservoir by using the peristaltic air pump.

[0004] The present disclosure further provides, on one hand, a system for generating a sheath fluid flow for a flow cytometer, comprising: a first peristaltic sheath fluid pump that pumps the sheath fluid; a first pressurized reservoir that receives the sheath fluid from the first peristaltic pump; a first fluid sensor that senses the amount of the sheath fluid in the first pressurized reservoir and generates a first sheath fluid quantity signal for controlling the first peristaltic sheath fluid pump to maintain a predetermined amount of sheath fluid in the first pressurized reservoir; a second peristaltic sheath fluid pump that pumps the sheath fluid; a second pressurized reservoir that receives the sheath fluid from the second peristaltic pump; a second fluid sensor that senses the amount of the sheath fluid in the second pressurized reservoir, the amount being used to control the second peristaltic sheath fluid pump to maintain a predetermined amount of sheath fluid in the second pressurized reservoir; and a peristaltic air pump that pumps air between the first pressurized reservoir and the second pressurized reservoir.

[0005] On the one hand, the present disclosure provides a method for generating a low-pulsation fluid flow, comprising: using a first peristaltic fluid pump to pump a fluid into a first pressurized reservoir; sensing the amount of the fluid in the first pressurized reservoir to generate a first fluid quantity signal; in response to the first fluid quantity signal, maintaining a predetermined amount of the fluid in the first pressurized reservoir by using the first peristaltic fluid pump to pump the fluid into the first pressurized reservoir and / or removing the fluid from the first pressurized reservoir; using a second peristaltic fluid pump to pump the fluid from the first pressurized reservoir to a second pressurized reservoir; sensing the amount of the fluid in the second pressurized reservoir to generate a second fluid quantity signal. signal; maintaining a predetermined amount of the fluid in the second pressurized reservoir by pumping the sheath fluid into the second pressurized reservoir using the second peristaltic pump in response to the second fluid quantity signal and / or removing the fluid from the second pressurized reservoir in response to the second sheath fluid quantity signal; supplying air to the first pressurized reservoir so as to pressurize the first pressurized reservoir; transferring air from the first pressurized reservoir to the second pressurized reservoir using the peristaltic air pump to pressurize the air in the second reservoir to a predetermined air pressure; and maintaining the predetermined air pressure in the second reservoir by transferring air into the second pressurized reservoir using the peristaltic air pump.

[0006] Also provided is a system for generating a low-pulsation fluid flow, comprising: a first peristaltic fluid pump; a first pressurized reservoir configured to receive fluid from the first peristaltic pump; a first fluid sensor that generates a first fluid quantity signal in response to the amount of the fluid in the first pressurized reservoir, and the system is configured to adjust the operation of the first peristaltic fluid pump at least partially in response to the first fluid quantity signal so as to maintain a predetermined amount of fluid in the first pressurized reservoir; a second peristaltic fluid pump that is configured to pump the fluid from the first pressurized reservoir; a second pressurized reservoir that receives the fluid from the second peristaltic pump; a second fluid sensor that generates a second fluid quantity signal in response to the amount of the fluid in the second pressurized reservoir, the system is configured to adjust the operation of the second peristaltic fluid pump at least partially in response to the second fluid quantity signal so as to maintain a predetermined amount of fluid in the second pressurized reservoir; and a peristaltic air pump that is configured to pump air between the first pressurized reservoir and the second pressurized reservoir.

[0007] Additionally disclosed are methods, including methods of operating a system according to the present disclosure, such as according to any of aspects 24-42.

[0008] Methods are further provided, including methods of performing flow cytometry using fluid delivered from a system according to the present disclosure, such as according to any of aspects 24-42.

[0009] Also disclosed is a method comprising: performing adjustments using a fluid circuit comprising: (i) a first pressurized reservoir in which at least some of the liquid is disposed, (ii) a second pressurized reservoir in which at least some of the liquid is disposed, (iii) a pump configured to transfer air between the first pressurized reservoir and the second pressurized reservoir, and (iv) a pump configured to transfer the fluid between the first pressurized reservoir and the second pressurized reservoir, the adjustments being: adjusting the air transferred to and / or drawn from the first pressurized reservoir and the second pressurized reservoir, and adjusting the fluid transferred to and / or drawn from the first pressurized reservoir and the second pressurized reservoir; performing the adjustments so as to maintain the second pressurized reservoir at a pressure that differs by no more than about 1% from the pressure of the first pressurized reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the drawings, which are not necessarily drawn to scale, like reference numerals may describe similar components in different views. The same reference numerals with different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various aspects discussed in this document by way of example and not limitation. In the drawings:

[0011] Figure 1 is a schematic illustration of an embodiment of a two-stage liquid flow system with reduced pulsation.

[0012] Figure 2 It is shown Figure 1 A schematic flow chart of the operation of a two-stage liquid flow system of an embodiment.

[0013] Figure 3 is a schematic diagram of an embodiment of an air supply system for supplying pressurized air to a pre-pressurization reservoir.

[0014] Figure 4 is a schematic block diagram of a control system that may be used with the disclosed embodiments. DETAILED DESCRIPTION

[0015] The present disclosure may be more readily understood by reference to the following detailed description of desired embodiments and the Examples included therein.

[0016] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those generally understood by those of ordinary skill in the art. In the event of a conflict, this document, including definitions, shall prevail. Although methods and materials similar or comparable to those described herein can be used in practice or testing, preferred methods and materials are described below. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. Materials, methods and examples disclosed herein are only illustrative and are not intended to be restrictive.

[0017] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0018] As used in the specification and claims, the term "comprising" may include the embodiments of "consisting of" and "consisting essentially of." As used herein, the terms "comprise(s)", "include(s)", "having / has", "may", "contain(s)" and variations thereof are intended to be open transitional phrases, terms or words that require the presence of a specified ingredient / step and allow the presence of other ingredients / steps. However, such descriptions should be understood to also describe a composition or method as "consisting of" and "consisting essentially of the enumerated ingredients / steps," which allows the presence of only the ingredients / steps together with any impurities that may result therefrom, and excludes other ingredients / steps.

[0019] As used herein, the terms "about" and "for or about" mean that the quantity or value in question may be a value that specifies some other value that is approximately or about the value. As used herein, it is generally understood that, unless otherwise indicated or inferred, the nominal value indicates a variation of ±10%. The term is intended to convey that similar values ​​promote equivalent results or effects listed in the claims. That is, it is understood that quantities, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller as needed, thereby reflecting tolerances, conversion factors, rounding, measurement errors, etc., and other factors known to those skilled in the art. In general, quantities, sizes, formulations, parameters, or other quantities or characteristics are "about" or "approximately", whether or not explicitly stated as such. It should be understood that when "about" is used before a quantitative value, unless otherwise specifically stated, the parameter also includes the specific quantitative value itself.

[0020] Unless indicated to the contrary, numerical values ​​should be understood to include the same value when reduced to the same number of significant figures and values ​​that differ from the stated value by less than the experimental error of conventional measurement techniques for determining the value as described in this application.

[0021] All ranges disclosed herein are inclusive of the recited endpoints and independent of the endpoints (e.g., "between 2 grams and 10 grams, all intermediate values ​​include 2 grams, 10 grams, and all intermediate values"). The endpoints of the ranges and any values ​​disclosed herein are not limited to the exact ranges or values; they are sufficiently imprecise to include values ​​approximating these ranges and / or values. All ranges are combinable.

[0022] As used herein, approximate language may be applied to modify any quantitative representation, which may change without causing a change in the basic function associated therewith. Therefore, in some cases, the value modified by one or more terms (such as "about" and "substantially") may not be limited to the specified exact value. In at least some examples, the approximate language may correspond to the accuracy of the instrument used to measure the value. The modifier "about" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the expression "from about 2 to about 4" also discloses a range of "from 2 to 4". The term "about" may refer to plus or minus 10% of the number shown. For example, "about 10%" may indicate a range of 9% to 11%, and "about 1" may mean from 0.9-1.1. Other meanings of "about" may be known from the context, such as rounding, so for example "about 1" may also mean from 0.5 to 1.4. In addition, the term "including" should be understood to have an open meaning of "including", but this term also includes the closed meaning of the term "consisting of..." For example, a composition including components A and B may be a composition comprising A, B, and other components, but may also be a composition made only of A and B. All documents cited herein are incorporated by reference in their entirety for any and all purposes.

[0023] picture

[0024] The following description of the non-limiting figures is exemplary only and does not limit the scope of the present disclosure or the appended claims.

[0025] Figure 1 is an illustration of a dual-stage fluidics system 100 with reduced pulsation in the sheath output 130. Figure 1 The system can be used for sorting flow cytometers, which require very stable sheath fluid delivery to maintain accuracy in sorting timing and prevent pulsation in the measurement signal or the frequency of particles arriving at the interrogation area of ​​the sorting flow cytometer. Peristaltic pumps are used in various types of instruments, especially in the medical field, because peristaltic pumps can isolate the fluid from all types of external contamination. Peristaltic pumps are relatively inexpensive and can produce pressures of 0-60 pounds per square inch (PSI) or more. Peristaltic pumps are also very reliable and have a relatively long service life. Due to the low cost and other advantages of using peristaltic pumps, various attempts have been made to make pulsation dampeners for peristaltic pumps. However, these dampeners have failed to eliminate or significantly reduce the inherent pulsating output of peristaltic pumps. The working principle of a peristaltic pump is to compress a pipe using a roller and rotate along the length of the pipe to produce a pumping action. Therefore, when the roller is lifted at the end of the pipe length, the pumping action produces a pressure wave in the pumped fluid.

[0026] To some extent, damping can be achieved by using a reservoir in which the sheath fluid can be pumped to a certain level and an air pump and air regulator can be used to supply air to the reservoir at a predetermined pressure to maintain the predetermined pressure so that the sheath fluid flows out of the reservoir at the predetermined pressure. While such a system can provide a fairly stable flow of sheath fluid, the air regulator is expensive and the accuracy of the pressure of the regulated air is maintained by the use of exhaust. The amount of exhaust is controlled by the orifice. Higher responsiveness can be achieved by using a larger orifice. However, a larger orifice results in more air being used. Therefore, in order to obtain a highly regulated air supply, a larger, more complex and more expensive pump is required, and the vibrations generated by the pump must also be managed to avoid interference vibrations that would alter the sorting process when used in a sorting type flow cytometer.

[0027] On the other hand, peristaltic pumps are much cheaper and have almost no vibration. Using a peristaltic pump to pump air instead of an expensive vibrating air pump solves the vibration problem and allows the air pressure in the reservoir to be carefully maintained because the peristaltic pump can be operated in both forward and reverse directions, making it possible to add or subtract air from the reservoir in a precise manner without having to bleed air through an air regulator. However, due to the pulsating nature of the peristaltic pump, using a peristaltic pump to pump air and sheath fluid requires a very large reservoir to create an adequate amount of damping to provide a sheath output flow suitable for use in a sorting flow cytometer. For example, if the reservoir is pressurized to 60 psi, then a reservoir of at least 25 liters is required to provide adequate damping. However, such a reservoir is too large for a sorting flow cytometer.

[0028] Reference again Figure 1 , a dual-stage fluidics system 100 is shown that uses two reservoirs, a pre-pressurized reservoir 106 and a secondary reservoir 126, and three peristaltic pumps 102, 118, and 120. The peristaltic pumps 102, 118, 120 are used to provide a reliable system for pumping both air and sheath fluid to produce a stable sheath output 130. By using two reservoirs, both of which are pressurized, and in the best case are pressurized to approximately the same pressure, the pulsatile nature of the peristaltic pumps has little effect on the stability of the sheath output 130. Approximately the same pressure is considered to be within approximately 1.0% of the pressure.

[0029] like Figure 1 As shown in FIG. 1 , the sheath fluid input 104 flows to the first peristaltic sheath fluid pump 102. The first peristaltic sheath fluid pump 102 pumps the sheath fluid input 104 and produces pumped sheath fluid 108. The pumped sheath fluid 108 is transferred to the pre-pressurized reservoir 106. The weight sensor 107 measures the weight of the pre-pressurized reservoir 106, and the computer control system 151 ( Figure 4) controls the flow rate of the sheath fluid 108 pumped into the pre-pressurized reservoir 106. The weight sensor 107 generates a weight signal, which is used to control the first peristaltic sheath pump 102 to pump additional fluid into the pre-pressurized reservoir 106 or to remove fluid from the pre-pressurized reservoir 106. Because the first peristaltic sheath pump 102 can be operated in either direction, that is, it can very accurately pump fluid into the pre-pressurized reservoir 106 or remove sheath fluid from the pre-pressurized reservoir 106, the amount or weight of the pre-pressurized fluid in the pre-pressurized reservoir can be maintained very accurately. Alternatively, the first peristaltic sheath pump can only be used to carefully add sheath fluid and stop pumping when the weight sensor 107 indicates that the weight of sheath fluid contained in the pre-pressurized reservoir 106 is appropriate. Therefore, the pre-pressurized reservoir 106 contains a predetermined amount of sheath fluid for filling the pre-pressurized reservoir 106 to a predetermined level. The remaining volume of the pre-pressurization reservoir 106 is filled with pressurized air from the pressurized air input 110. By maintaining the sheath fluid in the pre-pressurization reservoir 106 at a substantially constant level, the volume in the pre-pressurization reservoir 106 for pressurized air remains substantially constant, which makes it easier to maintain the air pressure in the pre-pressurization reservoir 106 and provides a more constant overall output pressure, given that the output pressure of the reservoir is related to both the air pressure and the fluid height.

[0030] like Figure 1 As shown in , the weight sensor 107 measures the weight of the pre-pressurized reservoir 106 and provides a signal to the first peristaltic sheath pump 102 through the computer control system 150, causing the first peristaltic sheath pump 102 to add sheath fluid 108 or remove sheath fluid from the pre-pressurized reservoir 106 so as to maintain a constant weight of sheath fluid in the pre-pressurized reservoir 106. The pressure transducer 112 carefully measures the air pressure in the pre-pressurized reservoir 106 and adjusts the pressurized air input 110 to maintain the pressurized air at a predetermined pressure, such as 60PSI, with a difference of 0.25PSI. Because the volume of the pre-pressurized reservoir 106 remains constant, it is easier to maintain a constant air pressure, as noted above. The pressurized air input 110 is composed of Figure 3 The air supply system 150 is generated, which is explained in more detail below.

[0031] It has also been found that a peristaltic pump, such as the peristaltic air pump 120, can produce air pressure variations when the air input pressure, such as from the pressurized air 114, is significantly different from the pressure of the output conditioned air 124. This occurs due to the pulsating nature of the peristaltic pump and the expansion and contraction of the tubing when the peristaltic pump is pumping from an unpressurized or low pressure source, resulting in changes in volume and, therefore, pressure variations. This change in volume can occur even with very rigid tubing, such as plastic tubing. However, it has been found that when the pressure of the input air, such as the pressurized air 114, and the conditioned air 124 are substantially the same, i.e., differ by no more than 1.0%, the expansion and contraction of the tubing is minimal. For example, if the pressurized air 114 is 60 PSI and the deviation is 0.25 PSI, it has been found that the pressure of the conditioned air 124 can be maintained at 60 PSI with a deviation of much less than 0.25 PSI, perhaps as low as 0.001 PSI, without significant changes in pressure due to the tubing.

[0032] The pressurized air 114 is the pressurized air present in the pre-pressurized reservoir 106 provided by the pressurized air input 110. Therefore, the pressurized air 114 is at the same level as the pressurized air input 110, for example, it can be 60PSI. The pressurized air 114 is the input of the peristaltic air pump 120. The output of the peristaltic air pump 120 is the regulated air 124. In an ideal embodiment, the pressure of the pressurized air 114 is the same as the pressure of the regulated air 124, that is, the difference does not exceed about 1.0%. However, this may not be the case. In various embodiments of the disclosed technology, the air pressure of the pressurized air 114 may be significantly different from the air pressure of the regulated air 124. The size of the difference will affect the size of the pressure fluctuation at the sheath output 130. Therefore, the pressure in the pre-pressurized reservoir can be any pressure higher than the ambient pressure, and as the pressure in the pre-pressurized reservoir 106 increases to the pressure of the regulated air 124, the pressure change at the sheath output 130 will decrease. Again, however, in order to minimize pressure fluctuations in the sheath output 130, a particularly suitable pressure for the pre-pressurized reservoir 106 is the same as the pressure of the conditioned air 124. Without being bound by any particular theory or embodiment, pulsation can be measured directly by pressure changes in the reservoir 126 or output 130 or by observing velocity shifts in the fluid stream after the fluid leaves the output 130. Pressure measurement is particularly convenient because the transducer 128 is already monitoring the pressure of the reservoir 126.

[0033] Reference again Figure 1 , the peristaltic pump 120 is used to isolate the pressurized air 114 from the conditioned air 124. The pressure transducer 112 detects the air pressure of the air inside the pre-pressurized reservoir 106. If the air pressure drops below a predetermined threshold, the computer control system 151 connected to the pressure transducer 112 will generate a signal that is sent to the Figure 3The control signal of the air supply system 150 is used to supply additional air through the pressurized air input 110, as described below with respect to Figure 4 If the pressure in the pre-pressurized reservoir 106 is too high, the dump valve 142 ( Figure 3 ) to remove the pressure, the valve Figure 3 The system disclosed herein is disclosed in more detail in the description of . Thus, the pressure of the pre-pressurized air 114 is ideally substantially the same as the air pressure in the pre-pressurized reservoir 106 (i.e., within the range of 60PSI±0.25PSI) or differs from it by approximately 0.4% to produce a fairly constant output pressure at the sheath output 130. Using the system disclosed herein, testing has shown that when the pressure in the pre-pressurized reservoir 106 is 60PSI, the variation can be maintained at only 0.25PSI. A pressure difference of less than 1.0% is considered to be approximately or substantially the same. Alternatively, a dump valve can be connected to the second reservoir 126 to reduce the pressure in the second reservoir 126.

[0034] Also like Figure 1 As shown, the conditioned air 124 is then applied to the second reservoir 126. The pressure transducer 128 reads the pressure in the second reservoir 126 and transmits the reading to the computer control system 151. If the conditioned air 124 is too high, the peristaltic pump 120 runs in reverse to remove air from the second reservoir 126. In this way, there is no loss of efficiency, such as when an air regulator is used, which results in a large amount of air being removed from the system and requires a large, expensive motor capable of providing a large amount of air.

[0035] Figure 1The pressurized sheath fluid 116 is shown pumped from the pre-pressurized reservoir 106 by the second peristaltic sheath pump 118. The second peristaltic sheath pump 118 pumps the pressurized sheath fluid 116 from the pre-pressurized reservoir 106 to the second reservoir 126 to produce a low pulsation sheath fluid 122. The second peristaltic sheath pump 118 can be operated in both forward and reverse directions to add or remove sheath fluid from the second reservoir 126, or can be operated only in the forward direction to add sheath fluid to the second reservoir 126. In the latter case, sheath fluid is added to the second reservoir until the weight sensor 127 indicates that a predetermined level has been reached. The threshold setting can be very tight so that the sheath fluid level in the second reservoir 126 can be accurately maintained. The pressure of the pressurized sheath fluid 116 can be 60 PSI or any desired level with minimal pressure fluctuations, such as 0.25 PSI. Because the pressure level of the pressurized sheath fluid 116 is substantially the same as the pressure of the low-pulsation sheath fluid 122, the fluctuation between the pressurized sheath fluid 116 and the low-pulsation sheath fluid 122 is very small because the difference between the input pressure of the pressurized sheath fluid 116 and the output pressure of the low-pulsation sheath fluid 122 is very small. Likewise, the smaller the difference, the more stable the sheath output 130. In addition, the second peristaltic sheath fluid pump 128 isolates the input and output so that changes in the pressurized sheath fluid 116 are not transmitted to the low-pulsation sheath fluid 122.

[0036] Also like Figure 1 As shown, the low pulsation sheath fluid 122 is transferred to the second reservoir 126. The second reservoir 126 is filled to a predetermined amount, as indicated by the weight sensor 127. By filling the second reservoir 126 with sheath fluid to a predetermined amount or a predetermined level, a specific volume of pressurized air is maintained in the second reservoir 126. Because the volume remains substantially constant, i.e., within 1.0%, it is easier to maintain the pressure substantially constant. To this end, the discharge pressure of the sheath fluid remains substantially constant so that changes in the total pressure in the second reservoir 126 cannot be attributed to changes in the discharge pressure. Regulated air 124 is applied to the second reservoir and produces an air pressure that is detected by the pressure transducer 128. If the air pressure in the second reservoir 126 is too high, then the pressure transducer provides a signal to the computer control system 151 ( Figure 4 ) transmits a signal, the computer control system generates a control signal 178 to control the peristaltic air pump 120, which can be operated in the direction of adding additional air or reducing air from the second reservoir 126. In this way, the air pressure in the second reservoir 126 can be monitored and maintained very closely to produce a very stable sheath output 130 with a very consistent pressure and flow output. Alternatively, a dump valve, such as Figure 2 The dump valve 129 shown in FIG. 1 maintains the air pressure in the second reservoir 126 and the peristaltic air pump 120 does not operate in the reverse direction.

[0037] Figure 2 Publicly corresponds to Figure 1 A schematic flow chart of a two-stage liquid flow system 100 according to an embodiment disclosed in Figure 2 As shown in FIG. 1 , a sheath fluid input 104 provides sheath fluid to the first peristaltic sheath fluid pump 102. The pumped sheath fluid 108 is delivered to the pre-pressurized reservoir 106 through a conduit. A weight sensor 107 detects the weight of the pre-pressurized reservoir 106 and generates a weight signal for controlling the first peristaltic sheath fluid pump 102 to maintain a predetermined amount of sheath fluid in the pre-pressurized reservoir 106. Because the first peristaltic sheath fluid pump 102 can add or subtract fluid by running in a forward or reverse direction, the amount of sheath fluid in the pre-pressurized reservoir 106 can be maintained very accurately. A pressurized air input 110 is provided to the pre-pressurized reservoir 106. Because the pre-pressurized reservoir 106 contains a predetermined amount of sheath fluid, a constant volume of space is provided in the pre-pressurized reservoir 106 for the pressurized air input 110. A pressure transducer 112 detects the air pressure in the pre-pressurized reservoir 106 and generates a pressure signal for controlling the pressurized air input 110. The pressurized air in the pre-pressurization reservoir 106 is supplied to the peristaltic air pump 120. The pressure of the pressurized air 114 is ideally substantially the same as the pressure of the regulated air 124, but may be at any pressure in order to reduce pressure variations in the sheath output 130. Thus, the peristaltic air pump 120 may supply air to the second reservoir 126 by simply adding additional air or reducing air without significantly changing the air pressure from the input air pressure of the pressurized air 114 to the regulated air 124. Alternatively, the dump valve 129 may be used to reduce the air pressure in the second reservoir 126. The regulated air 124 is applied to the second reservoir 126. The second reservoir 126 maintains the volume of the regulated air 124 substantially constant.

[0038] Also like Figure 2As shown, the pressurized sheath fluid 116 flows from the pre-pressurized reservoir 106 to the second peristaltic sheath pump 118. The pressure of the pressurized sheath fluid 116 is substantially the same as the low pulsation sheath fluid 122, so that the second peristaltic sheath pump 118 pumps the sheath fluid from the input to the output at substantially the same pressure. Likewise, the pressure of the pressurized sheath fluid can be any pressure, but the closer the pressure of the pressurized sheath fluid is to the low pulsation sheath fluid 122, the smaller the pressure variation of the sheath output 130. When the pressures are approximately the same, the pressure variation of the low pulsation sheath fluid 122 is small. For example, at a pressure of 60 PSI, a variation of only 0.001 PSI in the low pulsation sheath fluid 122 can be achieved because the input pressure and output pressure pumped by the second peristaltic sheath pump 118 are substantially the same. In this context, substantially the same means that the input pressure and the output pressure do not differ by more than about 1.0% to obtain good results. The low pulsation sheath fluid 122 is delivered to the second reservoir 126. The weight sensor 127 measures the weight of the sheath fluid in the second reservoir 126, which is used to generate a control signal for controlling the second peristaltic sheath fluid pump 118, such as Figure 4 The pressure transducer 128 detects the air pressure in the second reservoir 126 and generates a signal for the computer control system 151 ( Figure 4 ) The air pressure signal used. Therefore, the air pressure in the second reservoir 126 can be controlled so that the 60 PSI in the second reservoir 126 produces a deviation of less than 0.001 PSI, making the sheath output 130 stable and constant.

[0039] Figure 3is a schematic diagram of an air supply system 150. The air supply system 150 is capable of bringing the pressurized air input 110 to a pressure of 60 PSI or other similar pressures in a short period of time for the volume of air in the pre-pressurized reservoir 132. Using a peristaltic pump to supply the pressurized air input 110 is not a viable alternative because it would take a significant amount of time to use a peristaltic pump to supply a volume of air to the pre-pressurized reservoir 132. For example, a typical implementation would require approximately one to two hours of pumping before the peristaltic pump is used to raise the pressure in the pre-pressurized reservoir 132 to 60 PSI. Thus, a larger volume air pump, such as the air pump 138, is required. However, the air pump 138 is much smaller than an air pump that works with an air regulator, which requires exhaust to maintain accuracy. Thus, the air pump 138 is much smaller, provides much less vibration, and can supply a sufficient amount of air to raise the pressurized air input 110 to the desired pressure, such as 60 PSI, in less than a minute or several minutes. Smaller air pumps such as air pump 138 produce less vibration than air pumps that work with an air regulator. However, the size of air pump 138 must be such that it only operates intermittently and does not produce vibrations sufficient to interfere with the sorting process performed by the sorting flow cytometer. Air pump 138 has an air inlet 136 at ambient pressure and pumps pressurized air through a check valve 140. Check valve 140 prevents pressurized air input 110 from flowing back into the air pump and reduces the pressure of pressurized air input 110. Pressure transducer 112 reads the pressure in pre-pressurization reservoir 132 and generates an air pressure signal for controlling air pump 138 and dump valve 142. When the pressure is low, air pump 138 is activated to increase the pressure of pressurized air input 110. If the pressurization transducer 112 detects an air pressure greater than a predetermined threshold pressure, such as 60.25 PSI, the dump valve 142 is activated to carefully reduce the pressure to a pressure within a threshold of the desired pressure, such as 60 PSI plus 0.25 PSI. In this way, the pre-pressurized reservoir 132 can be maintained at a substantially constant level and can be pressurized in a relatively short period of time using the air pump 138 without generating excessive vibrations.

[0040] Figure 4 1 is a schematic block diagram of the computer control system 151. Figure 4, the first pressure transducer 112 generates a first pressure signal 154 that is applied to the computer controller 152. The second pressure transducer 128 generates a second pressure signal 156 that is applied to the computer controller 152. The first weight sensor 107 generates a first weight signal 158 that is applied to the computer controller 152. The second weight sensor 127 generates a second weight signal 160 that is applied to the computer controller 152. The computer controller uses each of these signals to generate a control signal. The computer controller 152 generates a control signal 162 that controls the first peristaltic sheath pump 102. The computer controller 152 generates a control signal 164 that controls the second peristaltic sheath pump 118. The computer controller 152 generates a control signal 166 that controls the peristaltic air pump 120. The computer controller 152 generates a control signal 168 that controls the air pump 138. The computer controller 152 generates a control signal 186 that is used to control the dump valve 142. In this way, each signal detected by the transducers and sensors is used to control the sheath pump, air pump, and dump valve to produce a stable and consistent sheath output flow 130.

[0041] Thus, embodiments of the disclosed technology can provide a very stable sheath fluid output and use a peristaltic pump that can operate in either direction of sheath fluid and air to maintain a highly constant and stable sheath fluid output. Two pressurized reservoirs are used, which are maintained with a predetermined amount of sheath fluid carefully maintained by two different peristaltic sheath fluid pumps. Highly accurate air pressure is maintained in the two pressurized reservoirs, thanks to the fact that a constant volume of air space is maintained in the two reservoirs. In addition, a peristaltic air pump is provided between the two reservoirs to isolate the air pressure of the first reservoir from the second reservoir. Since the pressure of the first pressurized reservoir is approximately the same as the pressure of the second pressurized reservoir, the function of the peristaltic air pump is to simply provide or reduce a certain amount of pressurized air from the second reservoir, and there is no need to significantly adjust the pressure between the two reservoirs. Alternatively, when the pressure in the second reservoir exceeds a predetermined threshold, a dump valve can be connected to the second reservoir to reduce the pressure in the second reservoir. In this way, a constant and very stable sheath fluid output can be provided.

[0042] aspect

[0043] The following aspects are merely illustrative and are not intended to limit the scope of the present disclosure or the appended claims.

[0044] Aspect 1. A method for generating a low-pulsation fluid flow, comprising: using a first peristaltic fluid pump to pump a fluid into a first pressurized reservoir; sensing the amount of the fluid in the first pressurized reservoir to generate a first fluid quantity signal; in response to the first fluid quantity signal, maintaining a predetermined amount of the fluid in the first pressurized reservoir by using the first peristaltic fluid pump to pump the fluid into the first pressurized reservoir and / or removing the fluid from the first pressurized reservoir; using a second peristaltic fluid pump to pump the fluid from the first pressurized reservoir to a second pressurized reservoir; sensing the amount of the fluid in the second pressurized reservoir to generate a second fluid quantity signal ; maintaining a predetermined amount of the fluid in the second pressurized reservoir by pumping sheath fluid into the second pressurized reservoir using the second peristaltic pump in response to the second fluid quantity signal and / or removing the fluid from the second pressurized reservoir in response to the second sheath fluid quantity signal; supplying air to the first pressurized reservoir so as to pressurize the first pressurized reservoir; transferring air from the first pressurized reservoir to the second pressurized reservoir using the peristaltic air pump to pressurize the air in the second reservoir to a predetermined air pressure; and maintaining the predetermined air pressure in the second reservoir by transferring air into the second pressurized reservoir using the peristaltic air pump.

[0045] Aspect 2. The method according to aspect 1, wherein maintaining the predetermined air pressure in the second pressurized reservoir further comprises maintaining the predetermined pressure in the second pressurized reservoir by removing air from the second pressurized reservoir using the peristaltic air pump.

[0046] Aspect 3. The method according to any one of aspects 1-2, wherein supplying air to the first pressurized reservoir comprises supplying air to the first pressurized reservoir at an air pressure substantially the same as the predetermined pressure.

[0047] Aspect 4. The method according to any one of aspects 1-3, wherein sensing the amount of the fluid in the first pressurized reservoir comprises weighing the first pressurized reservoir using a first weight sensor to generate the first fluid quantity signal.

[0048] Aspect 5. A method according to any one of Aspects 1-4, wherein maintaining a predetermined amount of the fluid in the first pressurized reservoir includes pumping the fluid into the first pressurized reservoir and removing the fluid from the first pressurized reservoir using the peristaltic fluid pump in response to the first fluid quantity signal.

[0049] Aspect 6. The method according to any one of aspects 1-5, wherein sensing the amount of the fluid in the second pressurized reservoir comprises weighing the second pressurized reservoir using a second weight sensor to generate the second fluid quantity signal.

[0050] Aspect 7. A method according to any one of Aspects 1-6, wherein maintaining the predetermined quantity of the fluid in the second pressurized reservoir includes pumping the fluid into the second pressurized reservoir and removing the fluid from the second pressurized reservoir using the second peristaltic fluid pump in response to the second fluid quantity signal.

[0051] Aspect 8. The method of any one of aspects 1-7, further comprising detecting air pressure in the first pressurized reservoir using a first pressure transducer and generating a first air pressure transducer signal from the first pressure transducer.

[0052] Aspect 9. The method of aspect 8, further comprising adjusting operation of the peristaltic air pump in response at least in part to the first air pressure transducer signal.

[0053] Aspect 10. The method of any one of aspects 8-9, further comprising adjusting operation of a release valve in fluid communication with the first reservoir in response at least in part to the first air pressure transducer signal.

[0054] Aspect 11. The method of any one of aspects 1-10, further comprising detecting the air pressure in the second pressurized reservoir using a second pressure transducer and generating a second air pressure transducer signal from the second pressure transducer.

[0055] Aspect 12. The method of aspect 11, further comprising adjusting operation of the peristaltic air pump at least in part in response to the second air pressure transducer signal.

[0056] Aspect 13. The method of any one of aspects 11-12, wherein maintaining the predetermined air pressure in the second pressurized reservoir comprises opening a release valve in fluid communication with the second reservoir at least partially in response to the second air pressure transducer signal.

[0057] Aspect 14. The method of any one of aspects 1-13, further comprising adjusting operation of a third fluid pump configured to remove fluid from the second pressurized reservoir in response at least in part to the second fluid quantity signal.

[0058] Aspect 15. The method of any one of aspects 1-14, further comprising adjusting operation of the first peristaltic fluid pump at least in part in response to the second fluid quantity signal.

[0059] Aspect 16. The method of any one of aspects 1-15, further comprising adjusting operation of the second peristaltic fluid pump in response at least in part to the first fluid quantity signal.

[0060] Aspect 17. The method of any one of aspects 1-16, further comprising adjusting operation of a valve to deliver input air to the first pressurized reservoir.

[0061] Aspect 18. The method according to aspect 17, wherein the input air is pressurized by a booster pump.

[0062] Aspect 19. The method of any one of aspects 1-18, wherein the air exiting the first pressurized reservoir is at a pressure that differs by no more than about 1% from the pressure of the air entering the second pressurized reservoir.

[0063] Aspect 20. The method of aspect 19, wherein the air exiting the first pressurized reservoir is at a pressure that differs by no more than about 0.5% from the pressure of the air entering the second pressurized reservoir.

[0064] Aspect 21. The method of any one of aspects 1-20, wherein the fluid exiting the first pressurized reservoir is at a pressure that differs by no more than about 5% from the pressure of the fluid entering the second pressurized reservoir.

[0065] Aspect 22. The method of aspect 21, wherein the fluid exiting the first pressurized reservoir is at a pressure that differs by no more than about 1% from the pressure of the fluid entering the second pressurized reservoir.

[0066] Aspect 23. The method according to any one of aspects 1-22, wherein the fluid is a sheath fluid, and the method further comprises transferring the sheath fluid from the second pressurized reservoir to a flow cytometer.

[0067] Aspect 24. A system for generating a low-pulsation fluid flow, comprising: a first peristaltic fluid pump; a first pressurized reservoir configured to receive fluid from the first peristaltic pump; a first fluid sensor that generates a first fluid quantity signal in response to the amount of the fluid in the first pressurized reservoir, and the system is configured to adjust the operation of the first peristaltic fluid pump at least partially in response to the first fluid quantity signal so as to maintain a predetermined amount of fluid in the first pressurized reservoir; a second peristaltic fluid pump that is configured to pump the fluid from the first pressurized reservoir; a second pressurized reservoir that receives the fluid from the second peristaltic pump; a second fluid sensor that generates a second fluid quantity signal in response to the amount of the fluid in the second pressurized reservoir, and the system is configured to adjust the operation of the second peristaltic fluid pump at least partially in response to the second fluid quantity signal so as to maintain a predetermined amount of fluid in the second pressurized reservoir; and a peristaltic air pump that is configured to pump air between the first pressurized reservoir and the second pressurized reservoir.

[0068] Aspect 25. The system of aspect 24, wherein the system is configured such that the peristaltic air pump operates to maintain the first pressurized reservoir and the second pressurized reservoir at substantially the same pressure.

[0069] Aspect 26. The system of any one of Aspects 24-25, wherein the first fluid sensor is configured to weigh the first pressurized reservoir.

[0070] Aspect 27. The system of any one of Aspects 24-26, wherein the first fluid sensor is configured to determine a fluid level in the first pressurized reservoir.

[0071] Aspect 28. The system of any one of Aspects 24-27, wherein the second fluid sensor is configured to weigh the second pressurized reservoir.

[0072] Aspect 29. The system of any one of Aspects 24-28, wherein the second fluid sensor is configured to determine a fluid level in the second pressurized reservoir.

[0073] Aspect 30. The system according to any one of aspects 24-29, further comprising a first pressure transducer for generating a first air pressure signal in response to the pressure within the first pressurized reservoir.

[0074] Aspect 31. The system according to any one of aspects 24-30, further comprising a second pressure transducer for generating a second air pressure signal in response to the pressure within the second pressurized reservoir.

[0075] Aspect 32. The system of any one of aspects 24-31, further comprising a first valve in fluid communication with the first pressurized reservoir.

[0076] Aspect 33. The system of aspect 32, wherein the valve reduces the air pressure in the first pressurized reservoir if the air pressure in the first pressurized reservoir exceeds a threshold pressure.

[0077] Aspect 34. The system of any one of aspects 24-33, further comprising a second valve in fluid communication with the second pressurized reservoir.

[0078] Aspect 35. The system of aspect 34, wherein the valve reduces the air pressure in the second pressurized reservoir if the air pressure in the second pressurized reservoir exceeds a threshold pressure.

[0079] Aspect 36. The system of any one of aspects 24-35, further comprising a booster pump configured to deliver air to the first pressurized reservoir.

[0080] Aspect 37. The system of aspect 36, wherein the booster pump is operable to maintain a predetermined pressure in the first pressurized reservoir.

[0081] Aspect 38. The system according to any one of Aspects 24-37, further comprising: a control signal generator, the control signal generator being configured to generate a first peristaltic pump control signal in response to the first fluid quantity signal, the first peristaltic pump signal being used to adjust the operation of the first peristaltic fluid pump to achieve a first predetermined amount of fluid in the first pressurized reservoir by pumping the fluid into the first pressurized reservoir in a forward direction and / or pumping the fluid out of the first pressurized reservoir in a reverse direction, the control signal generator being configured to generate a second peristaltic pump control signal in response to the second fluid quantity signal a pump control signal, wherein the second peristaltic pump signal is used to adjust the operation of the second peristaltic fluid pump to achieve a second predetermined amount of fluid in the second pressurized reservoir by pumping the fluid into the second pressurized reservoir in a forward direction and / or pumping the fluid out of the second pressurized reservoir in a reverse direction, and the control signal generator generates a peristaltic air pump control signal in response to a signal related to the pressure in at least one of the first pressurized reservoir and the second pressurized reservoir, and the peristaltic air pump control signal is used to adjust the operation of the peristaltic air pump to achieve a predetermined pressure in the second reservoir.

[0082] Aspect 39. A system according to any one of aspects 24-38, wherein the system is configured such that the fluid entering the second peristaltic fluid pump defines a pressure Pentry , the fluid leaving the second peristaltic pump defines the pressure P exit , and P exit With P entry The values ​​differ by no more than about 1%.

[0083] Aspect 40. The system according to aspect 39, wherein P exit With P entry The values ​​differ by no more than about 0.5%.

[0084] Aspect 41. The system according to any one of Aspects 24-40, further comprising a flow cytometer in fluid communication with the second pressurized reservoir.

[0085] Aspect 42. The system of any one of aspects 24-41, wherein the system is configured to maintain the second pressurized reservoir at a pressure that differs by no more than about 1% from the pressure of the first pressurized reservoir.

[0086] Aspect 43. A method comprising operating a system according to any one of aspects 24-42.

[0087] Aspect 44. A method comprising performing flow cytometry using a fluid delivered from the system according to any one of aspects 24-42.

[0088] Aspect 45. A method comprising: making adjustments using a fluid circuit, the fluid circuit comprising: (i) a first pressurized reservoir in which at least some of a liquid is placed, (ii) a second pressurized reservoir in which at least some of the liquid is placed, (iii) a pump configured to transfer air between the first pressurized reservoir and the second pressurized reservoir, and (iv) a pump configured to transfer the fluid between the first pressurized reservoir and the second pressurized reservoir, the adjustment being: adjusting the air transferred to the first pressurized reservoir and the second pressurized reservoir and / or drawn from the first pressurized reservoir and the second pressurized reservoir, and adjusting the fluid transferred to the first pressurized reservoir and the second pressurized reservoir and / or drawn from the first pressurized reservoir and the second pressurized reservoir; the adjustment being performed so as to maintain the second pressurized reservoir at a pressure that differs by no more than about 1% from the pressure of the first pressurized reservoir.

[0089] Aspect 46. The method according to Aspect 45, further comprising transferring at least some of the fluid from the second reservoir to a flow cytometer.

Claims

1. A method for generating a low pulsation fluid flow, comprising: pumping fluid into the first pressurized reservoir using a first peristaltic fluid pump; sensing an amount of the fluid in the first pressurized reservoir to generate a first fluid quantity signal; maintaining a predetermined amount of the fluid in the first pressurized reservoir by pumping the fluid into the first pressurized reservoir and / or removing the fluid from the first pressurized reservoir using the first peristaltic fluid pump in response to the first fluid quantity signal; pumping the fluid from the first pressurized reservoir to a second pressurized reservoir using a second peristaltic fluid pump; sensing an amount of the fluid in the second pressurized reservoir to generate a second fluid quantity signal; maintaining a predetermined amount of the fluid in the second pressurized reservoir by pumping sheath fluid into the second pressurized reservoir using the second peristaltic pump in response to the second fluid amount signal and / or removing the fluid from the second pressurized reservoir in response to the second sheath fluid amount signal; supplying air to the first pressurized reservoir to pressurize the first pressurized reservoir; transferring air from the first pressurized reservoir to the second pressurized reservoir using a peristaltic air pump to pressurize the air in the second pressurized reservoir to a predetermined air pressure; as well as The predetermined air pressure in the second pressurized reservoir is maintained by delivering air into the second pressurized reservoir using the peristaltic air pump.

2. The method of claim 1, wherein maintaining the predetermined air pressure in the second pressurized reservoir further comprises maintaining the predetermined air pressure in the second pressurized reservoir by removing air from the second pressurized reservoir using the peristaltic air pump.

3. The method of any one of claims 1 to 2, wherein supplying air to the first pressurized reservoir comprises supplying air to the first pressurized reservoir at an air pressure substantially the same as the predetermined air pressure.

4. The method of any one of claims 1 to 2, wherein sensing the amount of the fluid in the first pressurized reservoir comprises weighing the first pressurized reservoir using a first weight sensor to generate the first fluid quantity signal.

5. The method according to any one of claims 1 to 2, wherein maintaining a predetermined amount of the fluid in the first pressurized reservoir includes pumping the fluid into the first pressurized reservoir and removing the fluid from the first pressurized reservoir using the peristaltic fluid pump in response to the first fluid quantity signal.

6. The method of any one of claims 1 to 2, wherein sensing the amount of the fluid in the second pressurized reservoir comprises weighing the second pressurized reservoir using a second weight sensor to generate the second fluid quantity signal.

7. The method according to any one of claims 1 to 2, wherein maintaining the predetermined amount of the fluid in the second pressurized reservoir includes pumping the fluid into the second pressurized reservoir and removing fluid from the second pressurized reservoir using the second peristaltic fluid pump in response to the second fluid quantity signal. 8 . The method of claim 1 , further comprising sensing air pressure in the first pressurized reservoir using a first pressure transducer and generating a first air pressure transducer signal from the first pressure transducer. 9 . The method of claim 8 , further comprising adjusting operation of the peristaltic air pump in response at least in part to the first air pressure transducer signal.

10. The method of any one of claims 8-9, further comprising adjusting operation of a release valve in fluid communication with the first pressurized reservoir in response at least in part to the first air pressure transducer signal.

11. The method of claim 1 further comprising sensing air pressure in the second pressurized reservoir using a second pressure transducer and generating a second air pressure transducer signal from the second pressure transducer. 12 . The method of claim 11 , further comprising adjusting operation of the peristaltic air pump in response at least in part to the second air pressure transducer signal.

13. The method of any one of claims 11 to 12, wherein maintaining the predetermined air pressure in the second pressurized reservoir comprises opening a release valve in fluid communication with the second pressurized reservoir in response, at least in part, to the second air pressure transducer signal.

14. The method of any one of claims 1-2, 8-9, 11-12, further comprising adjusting operation of a third fluid pump configured to remove fluid from the second pressurized reservoir at least partially in response to the second fluid quantity signal.

15. The method of any one of claims 1-2, 8-9, 11-12, further comprising adjusting operation of the first peristaltic fluid pump in response at least in part to the second fluid quantity signal.

16. The method of any one of claims 1-2, 8-9, 11-12, further comprising adjusting operation of the second peristaltic fluid pump in response at least in part to the first fluid quantity signal.

17. The method of any one of claims 1-2, 8-9, 11-12, further comprising adjusting operation of a valve to deliver input air to the first pressurized reservoir.

18. The method of claim 17, wherein the input air is pressurized by a booster pump.

19. The method of any one of claims 1-2, 8-9, 11-12, 18, wherein the air exiting the first pressurized reservoir is at a pressure that differs by no more than about 1% from the pressure of the air entering the second pressurized reservoir.

20. The method of claim 19, wherein the air exiting the first pressurized reservoir is at a pressure that differs by no more than about 0.5% from the pressure of the air entering the second pressurized reservoir.

21. The method of any one of claims 1-2, 8-9, 11-12, 18, 20, wherein the fluid exiting the first pressurized reservoir is at a pressure that differs by no more than about 5% from the pressure of the fluid entering the second pressurized reservoir.

22. The method of claim 21, wherein the fluid exiting the first pressurized reservoir is at a pressure that differs by no more than about 1% from the pressure of the fluid entering the second pressurized reservoir.

23. The method of any one of claims 1 to 2, 8 to 9, 11 to 12, 18, 20, 22, wherein the fluid is a sheath fluid, and the method further comprises transferring the sheath fluid from the second pressurized reservoir to a flow cytometer.

24. A system for generating a low-pulsation fluid flow, comprising: a first peristaltic fluid pump; a first pressurized reservoir configured to receive fluid from the first peristaltic pump; a first fluid sensor that generates a first fluid quantity signal in response to the amount of the fluid in the first pressurized reservoir, and The system is configured to adjust operation of the first peristaltic fluid pump in response, at least in part, to the first fluid quantity signal so as to maintain a predetermined amount of fluid in the first pressurized reservoir; a second peristaltic fluid pump configured to pump the fluid from the first pressurized reservoir; a second pressurized reservoir receiving the fluid from the second peristaltic pump; a second fluid sensor that generates a second fluid quantity signal responsive to an amount of the fluid in the second pressurized reservoir, The system is configured to adjust operation of the second peristaltic fluid pump in response, at least in part, to the second fluid quantity signal so as to maintain a predetermined amount of fluid in the second pressurized reservoir; as well as A peristaltic air pump is configured to pump air between the first pressurized reservoir and the second pressurized reservoir.

25. The system of claim 24, wherein the system is configured such that the peristaltic air pump operates to maintain the first pressurized reservoir and the second pressurized reservoir at substantially the same pressure.

26. The system of any one of claims 24 to 25, wherein the first fluid sensor is configured to weigh the first pressurized reservoir.

27. The system of any one of claims 24 to 25, wherein the first fluid sensor is configured to determine a fluid level in the first pressurized reservoir.

28. The system of any one of claims 24 to 25, wherein the second fluid sensor is configured to weigh the second pressurized reservoir.

29. The system of any one of claims 24 to 25, wherein the second fluid sensor is configured to determine a fluid level in the second pressurized reservoir.

30. The system of any one of claims 24-25, further comprising a first pressure transducer for generating a first air pressure signal in response to pressure within the first pressurized reservoir.

31. The system of any one of claims 24 to 25, further comprising a second pressure transducer for generating a second air pressure signal in response to the pressure within the second pressurized reservoir.

32. The system of any one of claims 24-25, further comprising a first valve in fluid communication with the first pressurized reservoir.

33. The system of claim 32, wherein the first valve reduces the air pressure in the first pressurized reservoir if the air pressure in the first pressurized reservoir exceeds a threshold pressure.

34. The system of any one of claims 24 to 25, 33, further comprising a second valve in fluid communication with the second pressurized reservoir.

35. The system of claim 34, wherein the second valve reduces the air pressure in the second pressurized reservoir if the air pressure in the second pressurized reservoir exceeds a threshold pressure.

36. The system of any one of claims 24 to 25, 33, 35, further comprising a booster pump configured to deliver air to the first pressurized reservoir.

37. The system of claim 36, wherein the booster pump is operable to maintain a predetermined air pressure in the first pressurized reservoir.

38. The system of any one of claims 24 to 25, 33, 35, 37, further comprising: Control signal generator, the control signal generator being configured to generate a first peristaltic pump control signal in response to the first fluid quantity signal, the first peristaltic pump signal being used to adjust operation of the first peristaltic fluid pump to achieve a first predetermined amount of fluid in the first pressurized reservoir by pumping the fluid into the first pressurized reservoir in a forward direction and / or out of the first pressurized reservoir in a reverse direction, the control signal generator being configured to generate a second peristaltic pump control signal in response to the second fluid quantity signal, the second peristaltic pump signal being used to adjust operation of the second peristaltic fluid pump to achieve a second predetermined amount of fluid in the second pressurized reservoir by pumping the fluid into the second pressurized reservoir in a forward direction and / or out of the second pressurized reservoir in a reverse direction, The control signal generator generates a peristaltic air pump control signal in response to a signal related to the pressure in at least one of the first pressurized reservoir and the second pressurized reservoir, the peristaltic air pump control signal being used to adjust the operation of the peristaltic air pump to achieve a predetermined air pressure in the second pressurized reservoir.

39. The system according to any one of claims 24 to 25, 33, 35, 37, wherein the system is configured such that the fluid entering the second peristaltic fluid pump defines a pressure P entry , the fluid leaving the second peristaltic pump defines the pressure P exit , and P exit With P entry The values ​​differ by no more than about 1%.

40. The system of claim 39, wherein P exit With P entry The values ​​differ by no more than about 0.5%.

41. The system of any one of claims 24 to 25, 33, 35, 37, 40, further comprising a flow cytometer in fluid communication with the second pressurized reservoir.

42. The system of any one of claims 24 to 25, 33, 35, 37, 40, wherein the system is configured to maintain the second pressurized reservoir at a pressure that differs by no more than about 1% from the pressure of the first pressurized reservoir.

43. A method comprising operating a system according to any one of claims 24 to 42.

44. A method comprising performing flow cytometry using a fluid delivered from a system according to any one of claims 24 to 42.

45. A method comprising: The method comprises: utilizing a fluid circuit comprising: (i) a first pressurized reservoir having at least some of the liquid disposed therein, (ii) a second pressurized reservoir having at least some of the liquid disposed therein, (iii) a pump configured to transfer air between the first pressurized reservoir and the second pressurized reservoir, and (iv) a pump configured to transfer the fluid between the first pressurized reservoir and the second pressurized reservoir, the adjusting being: regulating the air delivered to and / or withdrawn from the first and second pressurized reservoirs, and regulating the fluid delivered to and / or withdrawn from the first and second pressurized reservoirs; The adjusting is performed so as to maintain the second pressurized reservoir at a pressure that differs by no more than about 1% from a pressure of the first pressurized reservoir.

46. ​​The method of claim 45, further comprising transferring at least some of the fluid from the second pressurized reservoir to a flow cytometer.

Images