A counter of atmospheric condensation nuclei

Abstract

Method and apparatus to enable detection, count, and recordation of properties of particles of ultrafine particle sizes (<0.1 micron) as well as particle of larger sizes with the use of a condensation nuclei counter configured to enable multiple stages of volume expansion with the use of an array of fluidly connectable chambers.

Description

A COUNTER OF ATMOSPHERIC CONDENSATION NUCLEICROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This International Patent Application claims priority from and benefit of the US Provisional Patent Application No. 63 / 560,286 filed on March 01, 2024, the disclosure of which is incorporated by reference herein.RELATED ART

[0002] The condensation nuclei (CN) are tiny aerosol particles (which may generally range in size from 1 Angstrom up to 1 mm) suspended in any gas, including ambient air within the built environment (inside buildings) or in the outdoor, natural environment. The term “condensation nuclei” is an operational definition, because techniques to detect or measure these particles utilize the process of condensation of water or some other condensable fluid to grow the CN into particles or droplets of larger size to be more efficiently detected. CN are synonymous with aerosol particles or other terms that comprise a class of substantially any combination of liquid, solid, or gel-like materials at sizes small enough for such materials to stay suspended in gas (air) for more than a few seconds.

[0003] Some, but not necessarily all condensation nuclei may provide surfaces onto which water vapor may condense or otherwise deposit to form a water droplet or an ice particle. In one environmentally relevant effect, CN can serve as the basic building blocks of clouds. Notably, not all clouds create precipitation, as rain droplets are much larger than cloud droplets; the temperature and the humidity of the atmosphere dictate whether water droplets stay in a form of a cloud or fall to the ground as rain, sleet, graupel, or snow, or another hydrometeor. The CN that can serve as the basic building blocks of clouds are referred to as cloud compensation nuclei (CCN). Understandably, the devices or apparatus configured as counters of CN that are not the same as the devices or apparatus configured as CCN counters, and counters of CCN and counters of CN are generally structured and exploited differently and separably from one another, considering different thermodynamics involved.

[0004] The technically-related International Patent Application No. PCT / US2023 / 078602 filed on November 03, 2023 and now published as WO 2024 / 097934 (the disclosure of which is incorporated herein by reference) discusses a specific methodology which - when implemented with a device configured to count both a) a sub-group of the CN that are not CCN and b) a subgroup of the CN that are CCN - provides the user with a capability to independently verify and at least partially characterize both sub-groups of the condensation nuclei in a variety of regimes. In comparison and contradistinction, implementations of this invention address the counter of the first variety of the CN only - that is, the counter of the CN that are not CCN, and that is referred herein as a "CN counter".

[0005] While the counter of CCN is a device that measures the number concentration of atmospheric particles upon which water vapor condenses at low values of supersaturation that are equivalent to those that occur with the formation of tropospheric liquid clouds, a CN counter is a device that is capable of measuring and is configured to measure the number concentration of particles upon which a vapor (typically water vapor) condenses at higher values of supersaturation as known in related art to induce activation and condensation, relative to equilibrium vapor pressure over the liquid phase of the substance. The operation of a conventional CN counter is associated with a change of pressure, temperature, and / or volume in the chamber of the counter (implemented optionally by varying a volume of the chamber) or through selective use of sequential regions of differing temperature and / or vapor supersaturation, to which the combination of a vapor of liquid (for example, water vapor) and the target aerosol particles is delivered. Existing CN counters (also commonly referred to as condensation particle counters, or CPCs) are recognized as being either extremely costly or bulky and prohibitively large in size - each of which characteristics substantially prevents, in practice, the use of conventional CN counters en mass at one location and / or in conjunction with modes of transportation that are sensitive to weight and / or size of the employed equipment and often in cases when such use may be required by a conventional research facility.

[0006] Implementations of the present invention address the need, persisting in related art, in a CN counter with a variable and flexible operation that accommodates different operational protocols (speeds / rates of CN measurement, operation at different temperatures,ability to recognize / see and / or differentiate particles of different sizes - down to and below 0.1 micron, when required, to name just a few). Recognition / detection of such particles of ultrafine size (below 0.1 micron) is critically important for human health, because they penetrate deepest into the lungs. These particles are ubiquitous in urban air, are produced in the home (i.e., following nucleation through condensation of cleaning products; or through production of soot from gas ranges), and have a wide variety of industrial sources. An inexpensive implementation of the CN counter discussed below provides transformative benefit to a number of industries and applications.SUMMARY

[0007] Embodiments of the invention provide a condensation nuclei (CN) counter apparatus that includes multiple (N >3) chambers fluidly connected together in a linear series to form an array of chambers. Each of such multiple chambers is defined by a corresponding volume enclosed within a corresponding shell. A first chamber of the array is located at an input end of the array and is equipped with at least one device that is configured (i) to deliver a vapor of a liquid and / or (ii) to deliver the liquid and / or (iii) to deliver a particle to a first volume of the first chamber; a first fluidic channel operably connected to an input of the first chamber and carrying therein a first valve configured to fluidly shut the first fluidic channel. A Ithchamber of the multiple chambers is attached in series with (to) a (J- 1 )thchamber of the multiple chambers with a corresponding Ithfluidic channel containing a Ithvalve therein, and is further attached in series with a (J+l)thchamber of the multiple chambers with a corresponding (J+l)thfluidic channel containing a (J+l)thvalve. Here, J > 2 and a chamber of the array located at an output end of the array is operably connected to a pump. The apparatus additionally includes an optical detection system containing an optical detector that is in optical communication with a volume of at least one chamber of the multiple chambers to form an image of contents of the volume of the at least one chamber of the multiple chambers. In at least one implementation, at least one of the following conditions is satisfied: (i) the optical detection system is in optical communicationwith the first volume and is configured to form a first image of contents of the first volume, and (ii) when each of the Ithvalve is open, the first chamber is un-obstructingly fluidly connected to the pump. Optionally, and substantially in every implementation, the number of multiple chambers N may be equal to or larger than 4 and / or 5 and / or 6 and / or 7 and / or 8 and / or 9 and / or 10. Alternatively or in addition - and substantially in every implementation - at least two chambers of the array may have different volumes and / or a volume of at least one chamber of the multiple chambers may be configured to enable differentiation between (and / or identification of) CN that possess different chemical properties. Substantially every embodiment of the apparatus may be structured to satisfy at least one of the following conditions: (a) at least one chamber of the multiple chambers is configured to maintain a corresponding volume of the at least one chamber at a substantially constant temperature; (b) the optical detection system is configured to simultaneously form optical images of multiple particles that have been illuminated with a chosen light; (c) the apparatus additionally includes a source of light configured to generate such chosen light; and (d) when the apparatus includes the source of light, a combination of the source of light and the optical detection system is configured to generate and / or to register such chosen light at (i) a wavelength that is subject to variation and / or (ii) a polarization state that is subject to variation.

[0008] Optionally, in every embodiment the apparatus may additionally include at least one auxiliary chamber fluidly connected with the array of chambers in parallel and fluidly connected to an auxiliary pump. When this is the case, such least one auxiliary chamber may optionally include multiple auxiliary chambers connected in a linear series with one another and forming an auxiliary array of chambers. Alternatively or in addition, and substantially in every implementation of the apparatus, the at least one device (with which the first chamber is equipped) may be complemented to contain a pliable wicking material holding the liquid and / or the apparatus may include in the volume of at least one chamber (of the multiple chambers) an optical element configured to spectrally disperse polychromatic light incident thereon.

[0009] Alternatively or in addition, and substantially in every implementation, the apparatus may include a microprocessor or dedicated electronic circuitry operably cooperated with a non-transitory tangible computer readable medium that contains computer readable program code thereon. Here, the computer readable program code includes a series of computer readable program steps to carry out the operations such as (i) illuminating contents of a volume of at least one chamber of the multiple chambers with chosen light; and / or (ii) reversibly closing and / or opening a valve of the apparatus; and / or (iii) operating the pump to reduce pressure in a volume of a chamber located upstream from the pump. Optionally, such computer readable program code may additionally include a series of computer readable program steps to carry out(a) the process of operating the apparatus to substantially abruptly vary the pressure from a first pressure to a second pressure; and the process of producing a count of particles contained in the volume of the at least one chamber that have become optically detectable by the optical detection system in the chosen light as a result of the process of operating; and / or (b) when the particle is a fluorescing particle, the process of detecting a wavelength-dependent light scattering pattern, produced by the particle using an optical element disposed in said volume of the at least one chamber; and / or (c) the process of determining a characteristic of first particles, contained in the volume of the at least one chamber of the multiple chambers, that have become optically detectable by the optical detection system in the chosen light as a result of the reversibly closing and / or opening (here, the characteristic includes at least one of a count, a geometrical size, a rate of movement, an acceleration of movement, a chemical property, and a shape); and / or (d) the process of generating a representation of a spatial density of the first particles as a function of: such characteristic thereof and / or as a function of a wavelength and / or as a function of a state of polarization of the chosen light used to illuminate the particles prior to the process of determining. Alternatively or in addition, substantially every embodiment of the apparatus may include a series of computer readable program steps to carry out at least one of operations (a) and(b). Operation a), performed when corresponding volumes of at least two of the multiple chambers attached to one another in series are merged with one another by opening corresponding one or more valves located in fluidic channels between said at least two of the multiple chambers, manifests in ascertaining a characteristic of second particles that arecontained in a volume of a chamber of the at least two of the multiple chambers, and that have become optically detectable by the optical detection system in the chosen light as a result of the corresponding volumes having been merged (here, the characteristic of the second particle includes at least one of a count, a geometrical size, a rate of movement, an acceleration of movement, a chemical property, and a shape). Operation b) manifests in generating a representation of a spatial density of the second particles as a function of the characteristic thereof and / or as a function of a wavelength and / or as a function of a state of polarization of the chosen light used to illuminate said particles prior to the ascertaining.

[0010] Embodiments additionally include method(s) for performing, with the use of such microprocessor or dedicated electronic circuitry, any of the above-identified processes and operations.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawing figures of which:

[0012] FIG. 1 illustrates schematically an embodiment of an apparatus structured to operate in an n-valve regime, according to the idea of the invention;

[0013] FIGs. 2 and 3 provide schematics of the embodiments configured to operate in a 3 -valve regime and a 1 -valve regime, respectively;

[0014] FIG. 4 contains plots illustrating experimental and theoretical data that shows critical diameter (Dcnr) of pure glutaric acid particles at which they induce activation, as a function of supersaturation (above 100% relative humidity). Reproduced from open access publication of Koehler, K.A., et al., Water activity and activation diameters from hygroscopicity data - Part II: Application to organic species. Atmos. Chem. Phys., 2006. 6(3): p. 795-809, the disclosure of which is incorporated herein by reference. Lower supersaturation requires larger particles to activate;

[0015] FIG. 5 represents experimental data reproduced from the open access publication by Petters, M.D. and S.M. Kreidenweis (A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. Phys., 2007. 7(8): p. 1961-1971) showing the critical supersaturation (water saturation above 100% relative humidity) required to activate particles composed of pure materials of varying hygroscopicity (K) and at varying dry particle diameter;

[0016] FIG. 6 illustrates relationship between water saturation ratio (left), particle diameter (right), and pressure drop following expansion of the volume, each for two different relative humidity (RH) values. Initial conditions before expansion and corresponding pressure drop are 1013 hPa (atmospheric pressure near sea level) and 298 K. Curves show that the greater the pressure drop (moving to the right) from initial conditions, the diameter that can active (gray curves) drop and the saturation ratio (black) increases. Reproduced from Saghafifar, H., et al., Characterization of a Modified Expansion Condensation Particle Counter for Detection of Nanometer-Sized Particles. Aerosol Science and Technology, 2009. 43(8): p. 767-780.

[0017] Generally, the sizes and relative scales of elements in Drawings may be set to be different from actual ones to appropriately facilitate simplicity, clarity, and understanding of the Drawings. For the same reason, not all elements present in one Drawing may necessarily be shown in another. While specific embodiments are illustrated in the figures with the understanding that the disclosure is intended to be illustrative, these specific embodiments are not intended to limit the scope of invention implementations of which are described and illustrated herein.DETAILED DESCRIPTION

[0018] According to the idea of the invention, the problems with detection of the ultrafine size CN exhibited by the conventional CN counters are addressed by devising an apparatus structured to condensation nuclei counter configured to enable multiple stages of expansion of a volume of gas or air with the CN being tested with the use of an array of fluidly connectable multiple cavities or chambers (referred, together, as an array of cavities orchambers). For the sake of definiteness of terminology, the main cavity of the array of multiple cavities of an embodiment of a CN counter structure according to the idea of the invention may be referred herein as a "chamber" (or "major chamber"), while any of the additional (neighboring) cavities of such array may be referred to as "ballast" (or "minor chamber"). The (reversible) enablement of fluid communication between the chamber and a given ballast of the array amounts to increase of the overall volume occupied by the CN. (As the skilled person will readily understand, the CN under test are initially containedin the atmosphere of the (major) chamber.)

[0019] While the change of the initial volume can be implemented - in at least one specific case - by configuring the chamber such as to vary its own volume (as discussed, for example, in WO 2024 / 097934), one implementation of the idea of the present invention includes fluidly connecting the chamber with multiple ballasts through corresponding valves (configured, depending on the specifics of a particular implementation, as shutters / doors, taps, or closures between the constituent volumes enclosed by the immediately neighboring cavities), as schematically shown in FIG. 1.

[0020] FIG. 1 illustrates one non-limiting embodiment 100 of the CN counter apparatus of the invention including the (major) chamber 102 and multiple ballasts (to be discussed below). The chamber 103 may be optionally - if so desired - configured as a chamber with a volume that is defined and limited by a volume-enclosing shell and that is necessarily maintained at a substantially constant temperature (that is, under optionally imposed operational and environmental constraints that substantially eliminate a temperature gradient across the chamber 102, he means for which are known in related art). To this end, the shell may be structured to include two opposite walls that are operationally configured to be maintained at the same temperature - thereby providing a situation when a gradient of temperature cannot be created across the chamber volume between such two opposite walls (in contradistinction with the operation of the structure discussed in WO 2024 / 097934). It is understood that in a related case, the chamber of the array of chambers of an embodiment of the CN counter may be structured to allow for modification of the internal volume of the chamber.

[0021] In reference to a schematic of FIG. 1, however, the internal volume of the chamber 102 is shown to be limited on two sides by top and bottom walls 104, 108 (referred to as top and bottom, for simplicity, one or both of which may be structured as plates of material having operationally substantially high thermal conductivity, and with at least one of which - for example, the bottom - a corresponding thermo-electric cooler device may be juxtaposed). The top and bottom may include aluminum, for example. The volume of the chamber 102 may also be limited with side wall(s) at least a portion of which is made optically transparent. Side wall(s) may be formed at least in part by, for example, a quasi-cylindrical wall 116, as shown (defining the main part of the chamber 102) that is made at least in part of a glass-like or more generally optically-transparent material.

[0022] As a skilled person will readily appreciate, the practical difficulty of counting the number of particles that are substantially smaller in size than about 1 micron (for example, on the order of 0.1 micron or even smaller), it is preferred to somehow increase the effective size of the particles - by, for example, covering such particles with liquid (water, for example) to form aerosol elements the dimensions of which are larger than those of the initial particles. (In comparison, particles that are substantially bigger can often be - under some circumstances - detected directly - for example optically, with the optical camera when they fall due to gravity.) According to the idea of the invention, several different ways of increasing the effective size of the particles to be detected may be employed.

[0023] One implementation involves introduction of extra liquid and / or liquid vapor into the chamber 102 before closing it for measurements. To this end, a hydrophilic or porous material (fin one case - at least one piece of chemical filter paper; not shown in FIG. 1 for simplicity of illustration) is placed inside the internal volume of the chamber 102 and wetted with such liquid to ensure increased humidity in the chamber 102. Alternatively or in addition - as shown in the schematics of FIG. 1 - an external humidifier 132 is used. The humidifier may be structured to include a closed internal the volume at least partially filled with liquid and / or be equipped with entrance and exit ports 136A, 136B, that lead the liquid and / or liquid vapor into volume of the chamber 102 through a fluidic valve VI. The chamber of such humidifier 132 may also contain a pliable wicking material, partly immersed in liquid through which theincoming aerosol passes through the input port 136A to take up liquid before entering the chamber 102. Notably, the process of humidification of the contents of the chamber 102 may be implemented by drawing or pushing air (or another gas) that includes target particles subject to measurement.

[0024] The optical detection system, a portion 140 of which is shown in FIG. 1, is optically connected with the volume of the chamber of the apparatus through the optically- transparent portion of the side wall 116, may be structured substantially conventionally to employ the registration of laser light scattering at the particles within the volume (as shown - with the use of the laser source 142 or, preferably and according to the idea of the invention, with the use of an optical camera configured to effectuate the counting of the target particles based on optical images of such particles that are taken simultaneously for all particles (by, for example, optically imaging the contents of the chamber 102 onto the optical detector of the optical detection system); not shown in FIG. 1 for simplicity of illustration.

[0025] In addition to the walls / shell of the major chamber having at least a portion made of optically transparent material, it may be advantageous to make such shell of optically-opaque material with multiple (in one case - two) optically-transparent windows, one for illumination of contents of the major chamber and another - for delivering the optical radiation from the major chamber for optical detection at the optical detector of the optical detection system. The use of such specific version of the chamber diminishes the problem of unwanted spurious reflections of light inside the chamber which compromise the integrity of the true, sought-after signals.

[0026] According to the idea of the invention, as represented by the generalized schematic of the embodiment of FIG. 1, the so-furnished major or main chamber 102 of the CN counter apparatus 100 is judiciously equipped with at least one branch (shown here as SI) containing one or more additional chambers (referred to, interchangeably, as ballasts) 150A, 150B, . . ., etc. The immediately-neighboring to one anther ballasts of the present ballasts are fluidly separated from one another by a corresponding valve of the multiple - for example, N- valves (shown here as V2, V3, V4, . .. ,V V, etc.) in such a fashion as to enable multiple stages of expansion of the volume of intaken gas / air (initially limited to the volume of the chamber 102) to probe CN of different geometrical sizes. Notably, within a given branch of ballasts - referring,for example, to branch SI expressly indicated in FIG. 1 (additional branches may be structured in parallel to branch SI, for example) numerous constituent ballasts may be configured in parallel and / or sequentially with one another, thereby forming an array of cavities / chambers of the overall apparatus 100.

[0027] This ballast-array structure provides the ability for multi-stage expansion of the overall volume occupied by the CN (which initially are contained in the major chamber 102) by "adding" one or more additional and (not necessarily equal to one another) volumes to the volume of the chamber 102 via opening corresponding valve(s). The corresponding reduction of pressure of CN-containing atmosphere of the overall internal volume of the apparatus 100 in turn relates to the resultant vapor supersaturation required and thus to the smallest detectable particle size. This also impacts the acquisition of time-dependent physical properties, which - as the person of skill will readily appreciate - cannot be viewed through other available techniques. By utilizing high vapor supersaturation, particles as small as a few nanometers may be detectable.

[0028] Notably, at least in one specific implementation, the various constituent ballasts of the apparatus 100 may be configured to only be involved to introduce the variation of the pressure by variably increasing the "zero pressure" volume rapidly added to the first, main chamber (in which case no additional chemicals or vapor are being added to the internal atmosphere by adding these additional ballasts to the major chamber 102). All of the condensing fluid / vapor in this case is limited to the main chamber 102 (and a space from which it is introduced to the main chamber). In this scenario, the optical interrogation will substantially always be performed in the main chamber only - and no optical interrogation will be required to be performed at any of the ballasts of the apparatus 100.

[0029] Alternatively or in addition, and while an implementation of the invention still employs an array of multiple cavities or chambers - not necessarily of the same volume - configured to accommodate the CN therein and judiciously reversibly fluidly interconnectedwith one another in parallel and / or sequential fashion, different chemical compositions may be optionally added to at least some of these cavities (for example, some of the ballasts of the apparatus 100) to advantageously expand the operationally-limited capability of the conventional CN counters by providing the ability to manipulate super saturation (when two or more of the cavities of the array are in fluid communication with one another) not only to differentiate CN of different geometrical sizes from one another but, in addition, to investigate chemical properties of such CN.

[0030] In context of configuring the apparatus to differentiate the composition of the particles and / or of fluid vapors potentially utilized, materials used in construction of the overall apparatus are preferably those that do not dissolve and / or are not damaged by different vapors solvents. Particles can have a wide range of all properties, including chemical composition. One such variable is the relative polarity / hydrophobicity of the molecules in the particle. For example, highly polar salts (e.g. sodium chloride or ammonium nitrate) are very hydroscopic and will activate / condense water at relatively lower supersaturations. In contrast, more strongly nonpolar organic compounds (e.g. oil droplets, long-chain fatty acids like oleic acid) would require much higher water supersaturation at a given particle size. If a more non-polar organic solvent were used for the condensing fluid (e.g. hexane, di ethylamine, acetone), the relative distribution of supersaturations required for a given particle size would shift based on the chemical composition, where particles with more exposed non-polar molecules would activate at lower supersaturation and thus smaller size. (This swapping of polar / non-polar condensing vapors could possibly be seen as analogous to the chemical analytical methods in liquid chromatography (i.e. normal-phase liquid chromatography using non-polar solvents or reverse-phase liquid chromatography using polar solvents). In this vein, even tiny particles may contain 105-l 010molecules, and so these can be a complex mixture of many types of molecules, making the overall practical determination of involved chemistry involved.

[0031] Notably, as was already alluded to above, a specific case the implementation of a portion of the apparatus configured as an optical particle counter does not have to employ conventional light-scattering methodology but, instead, may derive the particle count from optical images of the target particles formed with the use of an imaging detector such as anoptical camera. The use of the optical camera as a detector instead of the conventional employment of the laser light scattering technique provides an operational advantage in that one can record the whole process and can measure many CN simultaneously in at least two dimensions.

[0032] It would be appreciated by a skilled artisan that an embodiment of a CN counter structured according to the idea of the invention can operate generally in a 1 -valve, a 3 -valve, or n-valve formats. (FIG.l, for example, schematically illustrates the 4-valve system, while FIG. 2 addresses a 3 -valve system and FIG. 3 schematically illustrates the 1 -valve system.)

[0033] The 1 -valve format of the operation of the apparatus, schematically presented in the related embodiment of FIG. 3, is that in which the apparatus 100 employs only the major chamber 102 that is directly connected with the (preferably single) pump, thereby effectively not including any operating ballasts. Such situation may be achieved while the remaining ballasts of all present branches of ballasts of the overall apparatus 100 are operationally disengaged from the chamber 102 by opening the corresponding valves thereby creating a simple un-obstructed pipe-like fluid connection between the chamber 102 and the pump, corresponding valve(s)), with valve VI being upstream of the chamber 102 and the pump being downstream of the chamber. This format allows for a very simple, low-cost version of the CN-counting process. Here, air and particles are drawn into the chamber 102 while the valve VI is open. The expansion necessary to activate water condensation onto the particles is achieved when the valve VI is closed, whereupon the air flowing to the pump rapidly reduces the chamber pressure.

[0034] The 3-valve format of the apparatus 100 allows for more flexibility by adding an additional volume (or ballast) (optionally of a volume different from that of chamber 102) for variable levels of expansion (and thus supersaturation), which can thus probe to variable lower particle size cuts. In this mode of operation, the first valve VI is placed upstream of the chamber 102, the second valve V2 is placed between the chamber 102 and the additional ballast 150A, and the third valve V3 is placed between the additional volume / ballast 105 A and the pump. (All the rest of the ballast branches that may be present in the arrayed apparatus 100 are operationallyswitched off.) Air and particles (CN) are drawn into and through the chamber 102 when all three valves !\V1, V2, V3 are open. When valves VI and V2 are closed, but valve V3 is open, the air and particles are temporarily isolated in the chamber 102, leaving the pressure in the chamber 102 at ambient / atmospheric pressure, while the pressure in the additional volume of the ballast 150A is reduced. When the pressure in the ballast 105 reaches the appropriate level, valve V2 is opened to rapidly expand the volume from the chamber 102 into the additional volume of the ballast 150A. This allows for a faster expansion than that possible by using the 1 -valve format of the apparatus 100 (FIG. 3). To complete the cycle, all three valves are then opened again. In this process, the pressure in the additional volume 150A can be modified such that the resultant expansion pressure is optimized to activate fluid condensation onto particles of a desired particle size.

[0035] Additionally or in the alternative, the 3 -valve format can be expanded further to allow for use of additional n-volumes (ballasts), each of which would require an additional corresponding valve. This design allows for the means to achieve variable, sequential levels of expansion (and corresponding supersaturation) and thus sequentially lower detectable particle size. (This generalized schematics was already addressed in reference to FIG. 1) Using this format, the operational sequence would be initiated in the fashion similar to that of the apparatus operating in a 3 -valve format. After the first stage of expansion, the next in line valve would be opened to connect the next additional ballast volume to the chamber, for an additional level of volume expansion. This process may continue until the full battery / array of additional volumes / ballasts present in the CN counter apparatus is utilized.

[0036] The skilled artisan will readily appreciate that a thermodynamical basis for understanding the relationship between particles (condensation nuclei, CN) and the point at which they can adsorb water and grow into droplets (aka “activation”) is provided by Kohler theory (see, for example, Petters, M.D. et al., A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, in Atmos. Chem. Phys., 2007. 7(8): p. 1961-1971; and / or Kohler, H., The nucleus in and the growth of hygroscopic droplets, in Transactions of the Faraday Society, 1936. 32: p. 1152-1161, the disclosure of each of which is incorporated herein by reference).

[0037] This long-standing theory is central for explanation of processes by which targeted particles activate to form cloud droplets in the atmosphere and by which particles are grown to more easily detectable sizes within commercially available instruments, e.g. condensation nucleus counters (CN counters). As recognized in related art, one important practical outcome of the theory is that particles of decreasing size require a correspondingly greater supersaturation to induce activation (FIG. 4). The second practical outcome is that particles of greater hygroscopicity (i.e. greater affinity for water adsorption; e.g. particles dominated by polar ionic salts) begin to activate (i.e. to form droplets) at smaller original particle size than for particles of lower hygroscopicity (e.g., comprised of non-polar organic materials) (FIG. 5). When Kohler theory is applied to utilize quasi-adiabatic volume expansion to induce supersaturation for activation of all particles (i.e., as in the case of the CN counter operation), the third outcome is that the conditions require an increasingly larger pressure drop from initial conditions to induce activation as the particle size decreases (for constant material composition). A corollary to this point is that the supersaturation that can be achieved for a given particle size and composition increases as the magnitude of the pressure drop increases. These conclusions are highlighted in FIG. 6. Quantitative relationships can be derived from first principles of Kohler theory, and have also been the subject of much experimental work.

[0038] The above information thus lays the foundation for which an embodiment of the proposed CN-counter instrument operates. Here, a relatively higher supersaturation is achieved through inducing a quasi-adiabatic volume expansion to abruptly reduce chamber pressure (usually from a starting point at room atmospheric pressure). Using Kohler theory, it is understood that a greater supersaturation immediately develops, and so particles of much smaller diameter and / or of much lower hygroscopicity can be activated. By this method, particles of a few nanometers or lower may be activated and subsequently detected (for a counting method see, for example, Kurten, A., et al., Characterization of an Automated, Water -Based Expansion Condensation Nucleus Counter for Ultrafine Particles. Aerosol Science and Technology, 2005.39(12): p. 1174-1183; the disclosure of which is incorporated by reference herein). The detection involves recordation of particles in-real time using the simultaneous formation, with the use of the he optical detection system, of optical images of multiple (and optionally a majority of the) particles that have been illuminated with a chosen light. Optionally, as the person of ordinary skill in the art would readily appreciate, the detection of the particles may be based on the variation of the polarization of light incident onto the particles from outside of the major chamber 102 (~ 4 Stokes vectors) and such light already scattered by the particles (~ 16 elements of the Mueller matrix).

[0039] Generally, the ability to explore different supersaturation levels is performed with the use of the apparatus structured in a fashion described in reference to FIGs. 1, 2, and 3 that is computer-controlled (see 160 in FIG. 1) by adding several ballast external volumes (auxiliary chambers of different volumes), each with its communicating valve thereby enabling numerically different expansions of the main chamber volume during the CN measurement process. Simultaneously with or in alternation with expansion of volume occupied by the CN by a hand pump, a syringe, or through use of a mechanical pump.

[0040] References throughout this specification to "one embodiment," "an embodiment," "a related embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with the referred to "embodiment" is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. It is to be understood that no portion of disclosure, taken on its own and in possible connection with a figure, is intended to provide a complete description of all features of the invention.

[0041] For the purposes of this disclosure and the appended claims, the use of the terms "substantially", "approximately", "about" and similar terms in reference to a descriptor of a value, element, property or characteristic at hand is intended to emphasize that the value, element, property, or characteristic referred to, while not necessarily being exactly as stated,would nevertheless be considered, for practical purposes, as stated by a person of skill in the art. These terms, as applied to a specified characteristic or quality descriptor means "mostly", "mainly", "considerably", "by and large", "essentially", "to great or significant extent", "largely but not necessarily wholly the same" such as to reasonably denote language of approximation and describe the specified characteristic or descriptor so that its scope would be understood by a person of ordinary skill in the art. In one specific case, the terms "approximately", "substantially", and "about", when used in reference to a numerical value, represent a range of plus or minus 20% with respect to the specified value, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2% with respect to the specified value. As a non-limiting example, two values being "substantially equal" to one another implies that the difference between the two values may be within the range of + / - 20% of the value itself, preferably within the + / - 10% range of the value itself, more preferably within the range of + / - 5% of the value itself, and even more preferably within the range of + / - 2% or less of the value itself. The use of these terms in describing a chosen characteristic or concept neither implies nor provides any basis for indefiniteness and for adding a numerical limitation to the specified characteristic or descriptor. As understood by a skilled artisan, the practical deviation of the exact value or characteristic of such value, element, or property from that stated falls and may vary within a numerical range defined by an experimental measurement error that is typical when using a measurement method accepted in the art for such purposes.

[0042] The use of these terms in describing a chosen characteristic or concept neither implies nor provides any basis for indefiniteness and for adding a numerical limitation to the specified characteristic or descriptor. As understood by a skilled artisan, the practical deviation of the exact value or characteristic of such value, element, or property from that stated falls and may vary within a numerical range defined by an experimental measurement error that is typical when using a measurement method accepted in the art for such purposes.

[0043] The term “A and / or B” or a similar term is defined to be interchangeable with the term “at least one of A and B.”

[0044] While the invention is described through the above-described exemplary embodiments, it will be understood by those of ordinary skill in the art that modifications to, andvariations of, the illustrated embodiments may be made without departing from the inventive concepts disclosed herein. Disclosed aspects of a given embodiment, or portions of these aspects, may be modified or combined in ways not listed above.

[0045] For example, use of white light or different wavelengths of lasers or illumination sources, such as that operating at about 405 nm, may complement the discussed above methodology by open up aerosol spectrally-dependent properties for investigation. The use of liquids other than water in the humidifier 132 (for particle activation) , such as e.g. organic alcohols. Further, by leveraging the ballast volumes, a variety of time-dependent effects not available by conventional CN measurements might be probed. For example, a first expansion with one ballast volume (150A) could cause droplets that, by their fall, change the aerosol in some way, followed at a known time by a conventional measurement with CN from a different ballast expansion. This might provide additional information about the particle size distribution and other properties. For example, a first expansion having a short fall time, leaves a modified aerosol distribution, mentioned above, that can be probed by a follow-up expansion and aerosol analysis. Alternatively or in addition, the chamber in which the optical detection of the particle is implemented (such as, for example, the major chamber 102) may be equipped with substantially any incarnation of an optical element or device configured to spectrally disperse polychromatic light incident therein (in a simplest case - a diffraction grating) inside the chamber in which the optical detection of the particles is carried out to gain the ability to distinguish fluorescing particles by their fluorescence signatures, or non-fluorescing particles by their wavelength-dependent scattering patterns. Alternatively or in addition, liquid collected at the bottom of a given chamber / ballast could be collected for later analysis. For example, a trigger from a light scattering detector employed in a specific implementation of the apparatus could indicate a type of particle that might be of specific chemical or biological interest. Once detected, the liquid collected at the bottom of the chamber could be washed out into a different container for sample analysis.

[0046] Accordingly, the implementation of the idea of the invention should not be viewed as being limited to the disclosed embodiment(s).

Claims

CLAIMSWhat is claimed is:

1. A condensation nuclei (CN) counter apparatus comprising: multiple chambers including N >3 chambers fluidly connected together in a linear series to form an array of chambers, each of the multiple chambers defined by a corresponding volume enclosed within a corresponding shell, wherein a first chamber of the array is located at an input end of the array and is and equipped with at least one device configured (i) to deliver a vapor of a liquid and / or (ii) to deliver the liquid and / or (iii) to deliver a particle to a first volume of the first chamber; a first fluidic channel operably connected to an input of the first chamber and carrying therein a first valve configured to fluidly shut the first fluidic channel; wherein a Jlhchamber of the multiple chambers is attached in series with a (J-l )thchamber of the multiple chambers with a corresponding Ithfluidic channel containing a 1thvalve therein, and is further attached in series with a (J+l)thchamber of the multiple chambers with a corresponding (J+l)thfluidic channel containing a (J+l)thvalve, wherein J > 2, wherein a chamber of the array located at an output end of the array is operably connected to a pump; and an optical detection system containing an optical detector is in optical communication with a volume of at least one chamber of the multiple chambers to form an image of contents of said volume of the at least one chamber of the multiple chambers.

2. An apparatus according to claim 1, wherein the optical detection system is in optical communication with the first volume and is configured to form a first image of contents of said first volume and / or wherein, when each of the Jthvalve is open, the first chamber is un- obstructingly fluidly connected to the pump.

3. An apparatus according to claim 1, wherein N > 4, and / or wherein N > 5, and / or wherein N > 6, and / or wherein N > 7, and / or wherein N > 8, and / or wherein N > 9, and / or wherein N > 10.

4. An apparatus according to claim 1, wherein at least two chambers of the array have different volumes.

5. An apparatus according to claim 1, wherein a volume of at least one chambers of the multiple chambers is configured to enable differentiation between and / or identification of CN possessing different chemical properties in operation of the apparatus.

6. An apparatus according to claim 1, wherein at least one of the following conditions is satisfied:(6A) at least one chamber of the multiple chambers is configured to maintain a corresponding volume of the at least one chamber at a substantially constant temperature;(6B) the optical detection system is configured to simultaneously form optical images of multiple particles that have been illuminated with a chosen light; and(6C) the apparatus further comprises a source of light configured to generate said chosen light; and(6D) when the apparatus comprises the source of light, a combination of the source of light and the optical detection system is configured to generate and / or to register said chosen light at (i) a wavelength subject to variation and / or (ii) a polarization state subject to variation.

7. An apparatus according to claim 1, further comprising: at least one auxiliary chamber fluidly connected with said array of chambers in parallel and fluidly connected to an auxiliary pump.

8. An apparatus according to claim 7, wherein the at least one auxiliary chamber includes multiple auxiliary chambers connected in a linear series with one another and forming an auxiliary array of chambers.

9. An apparatus according to claim 1, wherein the at least one device contains a pliable wicking material holding said liquid.

10. An apparatus according to claim 1, further comprising, in the volume of at least one chamber of the multiple chambers, an optical element configured to spectrally disperse polychromatic light incident thereon.

11. An apparatus according to claim 1, further comprising: a microprocessor operably cooperated with a non-transitory tangible computer readable medium that contains computer readable program code thereon, the computer readable program code including a series of computer readable program steps to effect: illuminating contents of a volume of at least one chamber of the multiple chambers with chosen light; and / or reversibly closing and / or opening a valve of the apparatus; and / or operating the pump to reduce pressure in a volume of a chamber located upstream from the pump.

12. An apparatus according to claim 11, wherein said computer readable program code further comprises a series of computer readable program steps to effect: operating said apparatus to substantially abruptly vary the pressure from a first pressure to a second pressure; andproducing a count of particles contained in the volume of the at least one chamber that have become optically detectable by the optical detection system in the chosen light as a result of said operating.

13. An apparatus according to claim 11, wherein said computer readable program comprises a series of compute readable program steps to effect: when the particle is a fluorescing particle, detecting a wavelength-dependent light scattering pattern, produced by the particle using an optical element disposed in said volume of the at least one chamber.

14. An apparatus according to claim 11, wherein said computer readable program code further comprises a series of computer readable program steps to effect: determining a characteristic of first particles, contained in said volume of the at least one chamber of the multiple chambers, that have become optically detectable by the optical detection system in the chosen light as a result of said reversibly closing and / or opening, wherein the characteristic includes at least one of a count, a geometrical size, a rate of movement, an acceleration of movement, a chemical property, and a shape and / or generating a representation of a spatial density of the first particles as a function of said characteristic thereof and / as a function of a wavelength and / or as a function of a state of polarization of said chosen light used to illuminate said particles prior to the determining.

15. An apparatus according to claim 11, wherein said computer readable program code further comprises a series of computer readable program steps to effect: when corresponding volumes of at least two of the multiple chambers attached to one another in series are merged with one another by opening corresponding one or more valves located in fluidic channels between said at least two of the multiple chambers, ascertaining a characteristic of second particles that are contained in a volume of a chamber of said at least two of the multiple chambers, and that have become optically detectable by the optical detection system in the chosen light as a result of said corresponding volumes having been merged,wherein the characteristic of the second particle includes at least one of a count, a geometrical size, a rate of movement, an acceleration of movement, a chemical property, and a shape; and / or generating a representation of a spatial density of the second particles as a function of said characteristic thereof and / as a function of a wavelength and / or as a function of a state of polarization of said chosen light used to illuminate said particles prior to the ascertaining.

Images