Abstract:
The Portable Ultrafine Particle Sizer (PUPS) invention is provided. The PUPS is an instrument which can measure particle number concentration for particle sizes under 200 nanometers The PUPS has a compact design which allows it to be mounted on vehicles with relative ease. Size discrimination is accomplished using, a compact reverse Differential Mobility Analyzer (rDMA) Particle charging is accomplished using a low-cost method for corona ionization. Concentration measurements are completed using a unique flexible printed circuit board electrode which can be easily removed for cleaning, disposal or chemical analysis of collected particles at the end of its in situ measurement life.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to, claims the earliest available effective filing date(s) from (e.g., claims earliest available priority dates for other than provisional patent applications; claims benefits under 35 USC §119(e) for provisional patent applications), and incorporates by reference in its entirety all subject matter of the following listed application(s) (the “Related Applications”) to the extent such subject matter is not inconsistent herewith; the present application also claims the earliest available effective filing date(s) from, and also incorporates by reference in its entirety all subject matter of any and all parent, grandparent, great-grandparent, etc. applications of the Related. Application(s) to the extent such subject matter is not inconsistent herewith. 
         [0002]    U.S. provisional patent application 61/279,460, entitled “Portable Ultrafine Particle Sizer”, naming Andrew Vize, Matthew Casari, Britt Holmen, and Jeff Frolik, as inventors, filed 21 Oct. 2009. 
     
    
     REFERENCE TO U.S. GOVERNMENT INTEREST 
       [0003]    “The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant DTRT06-G-0018 awarded by U.S. Department of Transportation.” 
     
    
     BACKGROUND 
       [0004]    1. Field of Use 
         [0005]    This application relates to the measurement of air pollution and in particular to the rapid measurement of the quantity and size distribution of aerosol particles. As vehicle engines become more complex and varied, it becomes necessary to have better systems to determine our motor vehicle emissions inventories. To develop accurate ultrafine particle models, the common practice of using engine dynamometers and in-lab testing will need to be replaced with in-situ monitoring of vehicles on the road. However, measurement of engine exhaust particle size is currently done using instruments that are too bulky, expensive, and power inefficient to easily adapt to on-board, in-situ particle measurement. 
         [0006]    2. Description of Prior Art (Background) 
         [0007]    There are several limitations with current systems for measuring engine exhaust particles, in particular ultrafine particles, or particle diameters less than 100 nanometers. Measuring ultrafine particulate is typically done in a laboratory setting. Particulate monitoring instruments are bulky and not designed for in-situ (i.e., on board and real-time) particulate monitoring. Those particulate sizing instruments are generally connected to engine dynamometers which are operated at loads to roughly simulate on-road conditions and are not suitable for in-situ fleet-wide monitoring of engine exhaust particles. 
         [0008]    In one optical system, light is directed through aerosol particle-laden smoke and the attenuation of the light is measured on a detector to indicate total particle concentration. This method does not measure particle size distribution, however. Another optical method uses light scattering to measure particle size by causing the particles to pass one at a time through a chamber so that scattered light amplitude depends on the particle size. The amplitude is measured by a photomultiplier which produces an electrical signal dependent upon particle size. To isolate single particles for detection, gas sampling must be done at low velocity, and the system is usually provided with very narrow pipes which are subject to contamination, require frequent cleaning, and tend to collect the larger particles before their entry into the sensing chamber. Further, such method of measuring the size of a single particle is quite slow, requiring perhaps as much as an hour for a typical measurement. 
         [0009]    Electrical methods have the advantage that they can be operated nearly continuously with the results available to the operator after a very short interval of time. In one electrical Method described in U.S. Pat. No. 3,114,877 to Dunham, a charging device operates to charge separate groups of aerosol particles passing the device. The particles then flow in a random manner through a field-free region, pass an ion trap and flow to a detector. At the detector, the particles lose their charge and produce a current. Although the detector current in the Dunham apparatus is said to be an index of the number of particles, it is clear that the amplitude of the current is a function of the total charge on all of the particles sensed by the detector at a given moment. Thus, the amplitude of the current is a function of the total surface area of the particles. Because the particles flow in a random, manner to the detector, particles having different surface areas (and thus different sizes) lose their charge at the same moment of time to produce the current. Therefore, the output current in the Dunham apparatus is not indicative of the number of particles except when they are of uniform size. 
         [0010]    Another method which indicates aerosol particle size distribution is based on the mobility of charged particles in an electric field extending radially across a tube in which the particles flow. Mobility is a measure of the velocity of a charged particle in an electric field, and generally speaking, the higher the charge on the particle the higher the mobility. For a given method of charging a particle, the amount of charge on the particle is a function of the size of the particle. Therefore, mobility is a function of particle size and methods based on particle mobility utilize the difference in mobility to measure particle size distribution. In one such device described in U.S. Pat. No. 3,413,545 to Whitby, clean air is caused to move downwardly in an annular flow path surrounding an elongated electrode extending axially in a cylindrical housing. Charged aerosol particles are introduced around the outer periphery of the flow path of clean air and an electric potential is applied across the elongated electrode and the cylindrical housing. For any given potential, particles having mobility below a certain value will not move far enough radially to contact and lose their charge to the elongated electrode before passing its downstream end. An electrometer detects these charged particles which generate a current, the amplitude of which is a function of the total charge on the detected particles. By varying the potential applied to the elongated electrode, more or fewer charged particles will reach the detector and induce the current. By relating the current produced when various potentials are applied to the elongated electrode, a measure of particle size distribution can be obtained. However, a number of factors limit the usefulness of this device for monitoring effluents in stacks of industrial installations, for example. Due to the method of charging, known as diffusion charging, only particles less than about 2 microns diameter can be measured whereas in a typical stack, particles up to 100 microns or more will be present. Further, the diffusion charging method is also inconvenient because it requires a source of compressed air and various thin pipes which are subject to clogging. 
         [0011]    Accordingly, there is a need for a method and apparatus for a compact, low-cost, low power system capable of discriminating and measuring in-situ particle size distribution based on particle mobility in an electric field utilizing a small volume differential mobility analyzer and disposable electrodes. 
       BRIEF SUMMARY 
       [0012]    The foregoing and other problems are overcome, and other advantages are realized, in accordance with the presently preferred embodiments of these teachings. 
         [0013]    In accordance with one embodiment of the present invention an apparatus for measuring aerosol particle concentration and particle size distribution is provided. The apparatus includes a corona ionizer utilizing a high voltage tungsten needle and a concentric ground ring for applying a negative high voltage potential to the aerosol particles. Also included is a reverse differential mobility analyzer (rDMA) for separating charged particles based on electrical mobility, wherein the rDMA includes a charged central repulsion electrode for driving the charged particles towards flexible printed circuit board detectors sized according to predetermined dimensions corresponding with particle sizes of interest. 
         [0014]    In accordance with another embodiment of the present invention a portable ultrafine particle measuring apparatus for measuring aerosol particle concentration and particle size distribution is provided. The apparatus includes a corona ionizer for applying a negative charge via a negative high voltage potential to the aerosol particles. Also included is at least one conductive needle support having precision-machined flow pathways for the aerosol gas sample. The apparatus also includes a non-conductive needle support for supporting the tungsten needle and electrically insulating the conductive needle support from the ground ring electrode. The apparatus further includes a reverse differential mobility analyzer (rDMA) for separating charged particles based on electrical mobility. The rDMA contains a central repulsion electrode and flexible printed circuit boards (PCB) for detecting charged particles. Included in the apparatus is a converter for converting the detected current induced by charged particles to a digital signal. 
         [0015]    The invention is also directed towards a portable ultrafine particle sizer system for measuring sizes of particles in an aerosol gas sample. The system includes a pump and a proportional valve for pumping aerosol gas samples through the system. A flow meter connectable to at least one pump measures aerosol gas flow through rates set by the pump and the proportional valve. A positive or negative corona ionizer with a tungsten needle ionizes particles within the aerosol gas sample and the reverse differential mobility analyzer (rDMA) determines particle size distribution based upon the ionized particles and separates the particles based upon different electrical mobility. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0017]      FIG. 1  is a pictorial illustration of one embodiment of the Portable Ultrafine Particle Sizer (PUPS) apparatus in accordance with the present invention; 
           [0018]      FIG. 2  is a transparent illustration of the PUPS invention shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a transparent cross sectional illustration of the invention shown in  FIG. 1 ; 
           [0020]      FIG. 4  is an enlarged transparent cross sectional illustration of the input port end of the invention shown in  FIG. 3 ; 
           [0021]      FIG. 5  is a cross sectional illustration of the Corona Ionizer &amp; Sheath Air Injection Module in accordance with the invention shown in  FIG. 4 ; 
           [0022]      FIG. 6  is a rotated illustration of the Corona ionizer &amp; Sheath Air Injection Module shown in  FIG. 5 ; 
           [0023]      FIG. 7  is a pictorial illustration of the Corona Ionizer module in accordance with the invention shown in  FIG. 1 ; 
           [0024]      FIG. 8  is a cross sectional pictorial illustration of the Corona Ionizer module in accordance with the invention shown in  FIG. 7 ; 
           [0025]      FIG. 9  is a pictorial illustration of the Corona needle support in accordance with the invention shown in  FIG. 6 ; 
           [0026]      FIG. 10  is a pictorial illustration of the Corona Ionizer Internal Assembly in accordance with the invention shown in  FIG. 1 ; 
           [0027]      FIG. 11  is a pictorial illustration of a cross section of the Corona Ionizer Internal Assembly in accordance with the invention shown in  FIG. 10 ; 
           [0028]      FIG. 12  is a rotated illustrated view of the Corona Ionizer shown in  FIG. 7 ; 
           [0029]      FIG. 13  is a cross sectional illustration of the flex-PCB inside the rDMA housing in accordance with the invention shown in  FIG. 3 ; 
           [0030]      FIG. 14  is an illustrated layout of the flexible Printed Circuit Board (flex-PCB) in accordance with the invention shown in  FIG. 13 ; and 
           [0031]      FIG. 15  is a functional flow diagram of the PUPS apparatus in accordance with the invention shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Referring now to  FIG. 1  there is shown a pictorial illustration of one embodiment of the Portable Ultrafine Particle Sizer (PUPS) Assembly  102 . The PUPS assembly includes Flexible Printed Circuit Board (flex-PCB)  104 , Sheath Gas Injection Module  106 , rDMA housing  108 , aluminum end cap  110 , fasteners  144 , and push-on hose fittings  142 . It will be understood throughout that fittings  142  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  144  may be any suitable mechanical plug. The sheath gas injection module  106  provides concentric alignment of the corona ionizer (See  FIG. 7-702 ), sheath gas flow straightener (See  FIG. 2-212 ), repulsion electrode (See  FIG. 2-214 ), and rDMA housing  108 . The sheath gas injection module  106  also serves the dual purpose of creating a constant gas pressure across the surface of the sheath gas flow straightener (See  FIG. 2-212 ). The rDMA Housing  108  is generally comprised of Polypropylene material; however, it will be understood that the rDMA Housing  108  could be any structurally and chemically stable non-conductive material. The rDMA housing  108  is designed to provide precise alignment of the flex-PCB (See  FIG. 14-1402 ) along the length and radius of the rDMA housing  108 , and provide the sealed pneumatic environment. 
         [0033]    The PUPS  102  is a composite of Aluminum, PTFE Teflon, Polypropylene and Tungsten. However, it will be understood that any suitable metal or material having characteristics similar to, or exceeding, one or more material characteristics associated with aluminum, PTFE Teflon, Polypropylene, or Tungsten may be used. The PUPS assembly is comprised of two main parts, a corona ionizer (See  FIG. 7-702 ) and a reverse differential mobility analyzer (rDMA)  108 . In the corona ionizer (See  FIG. 7-702 ) a negative high voltage potential is applied from a Tungsten needle (See  FIG. 8-824 ) to a concentric ground ring electrode (See  FIG. 8-822 ). Electrons are generated in the localized atmospheric breakdown around the Tungsten needle (See  FIG. 8-824 ). These electrons drift outward and become attached to the aerosol particles passing through the corona ionizer (See  FIG. 7-702 ), thus creating negatively charged aerosol particles. 
         [0034]    In the rDMA  108  a negative high voltage potential is applied from a central repulsion electrode (See  FIG. 2-214 ) to a concentric ground cylinder. Particles entering the rDMA  108  are repelled away from this central rod  214  by electrostatic force toward a series of ring electrodes. The PUPS  102  is designed to separate particles based on aerosol diameters between approximately 10 nm and 200 nm. Smaller particles are repelled more readily than particles that are larger comparatively and impact the ring electrode upstream, respectively (See  FIG. 13-1340 ). 
         [0035]    The end cap  110  provides alignment of the repulsion electrode ( 214 ) and the exhaust gas flow straightener (See  FIG. 2-216 ). The conical internal surface of the end cap  110  promotes constant gas pressure across the face of the exhaust gas flow straightener (See  FIG. 2-212 ). 
         [0036]    Referring also to  FIG. 2  there is shown a transparent illustration  202  of the PUPS invention shown in  FIG. 1 . Included in this illustration is—Flexible Printed Circuit Board (flex-PCB)  204 —See Item  1402 , Sheath Gas Injection Module  206  (See also  FIG. 1-106 , rDMA Housing  208  (See also  FIG. 1-108 ), End Cap  210  (See also  FIG. 1-110 ), and Electrical Grade PTFE Teflon Sheath Gas Flow straightener  212 . The sheath gas flow straightener  212 , with an array of holes, induces fluid flows in parallel layers. The sheath gas flow straightener  212  is designed to promote laminar flow of sheath gas as it enters the rDMA  108 . It will be further understood throughout that fittings  242  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  244  may be any suitable mechanical plug. 
         [0037]    Still referring to  FIG. 2 , there is shown aluminum repulsion electrode  214 . The repulsion electrode  214  is a cylindrical rod of suitably conductive material with known dimensions. A negative high voltage is applied to the electrode  214  thus inducing a repulsive electrostatic force on the negatively charged aerosol particles. Also shown is Electrical Grade PTFE Teflon Exhaust Gas Flow Straightener  216 . The exhaust gas flow straightener is a round disk with an array of holes through it. It is designed to promote constant flow of gas through radial cross section of the rDMA  108 . Still referring to  FIG. 2 , there is shown the Glass Filled Polyetheretherketone Aerosol Injection Manifold  214 A—The aerosol injection manifold  214 A serves the dual purpose of centering the repulsion electrode  214  in the exit of the corona ionizer (See  FIG. 7-702 ) and it promotes tracking of the aerosol streamlines along the surface of the repulsion electrode  214  while no electrostatic forces are applied. 
         [0038]    Referring also to  FIG. 3 , there is shown a cross sectional view of the complete PUPS Assembly  302 .  FIG. 3  illustrates the spatial relationship of flexible printed circuit board  304 , sheath gas injection module  306  (See  FIG. 1-106 ), rDMA Housing  308  (See  FIG. 1-108 ), End Cap  310  (See  FIG. 1-110 ), Sheath Gas Flow Straightener  312 —(See  FIG. 2-212 ), Repulsion Electrode  314  (See  FIG. 2-214 ), Exhaust Gas Flow Straightener  316  (See  FIG. 2-216 ), and Corona Ionizer Housing  318  (See  FIG. 7-726 ). It will be understood throughout that fittings  342  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  344  may be any suitable mechanical plug. 
         [0039]    Referring also to  FIG. 4 , there is shown a zoomed partial cross section  402  of the PUPS Assembly  102 .  FIG. 4  illustrates the spatial relationship of Sheath Gas Injection Module  406  (See  FIG. 1-106 ), Sheath Gas Flow Straightener  412  (See  FIG. 2-212 ), and Corona Ionizer Housing  418  (See  FIG. 7-726 ). It will be understood throughout that fittings  442  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  444  may be any suitable mechanical plug. 
         [0040]    Referring also to  FIG. 5 , there is shown a Cross Sectional View  502  of Corona Ionizer (See  FIG. 7-702 ) and Sheath Air Injection Module  506  (See  FIG. 1-106 ).  FIG. 5  further illustrates the spatial relationship of the Sheath Gas Injection Module  506  (See  FIG. 1-106 ), the Sheath Gas Flow Straightener  512  (See  FIG. 2-212 ), and the Corona Ionizer Housing  518  (See  FIG. 7-726 ). It will be understood throughout that fittings  542  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  544  may be any suitable mechanical plug. 
         [0041]    Referring also to  FIG. 6 , there is shown a Rotated View  602  of Corona Ionizer  502  (See  FIG. 7-702 ) and Sheath Air Injection Module  606  (See  FIG. 1-106 ).  FIG. 6  further illustrates the spatial relationship of the Sheath Gas Injection Module  606  (See also  FIG. 1-106 ), Sheath Gas Flow Straightener  612  (See also  FIG. 2-212 ), and Corona Ionizer Housing  618  (See also  FIG. 7-726 ). It will be understood throughout that fittings  642  may be any suitable push-on hose fitting or any other suitable hose connector. Likewise plugs  644  may be any suitable mechanical plug. 
         [0042]    Referring also to  FIG. 7  there is shown a pictorial illustration of the Corona Ionizer module  702 . The Corona Ionizer  702  is a composite of PTFE Teflon, brass, copper buss wire, Aluminum, and Tungsten. Aerosol passing through the corona ionizer  702  passes through a cloud of free electrons induced by a localized breakdown in the atmosphere surrounding a Tungsten corona needle (See  FIG. 8-824 ). A flow of negatively charged aerosol particles exit the corona ionizer  702 . 
         [0043]    Also shown in  FIG. 7  is Plated Copper Electrical Buss Wires  720 —These wires make electrical contact between the electrodes of the corona ionizer  702  and the external screw connectors.  FIG. 7  also shows: Stainless steel Ground Set Screw and Brass Fitting  722 , this brass insert and set screw  722  hold the ground ring electrode (See  FIG. 8-822 ) in place and creates the electrical connection; High Voltage Set Screw and Brass Fitting  724 , this brass insert and set screw hold the conductive corona needle support (See  FIG. 8-828 ) in place and creates the electrical connection; and PTFE Teflon Corona ionizer Housing  726 , this housing provides a chemically resistant, sealed environment which provides electrical isolation for the negative high voltage potentials present. 
         [0044]    Referring also to  FIG. 8  there is shown—Cross Section View of the Corona Ionizer  802  (See also  FIG. 7-702 ). Included in this view are Electrical Buss Wire  820  (See also  FIG. 7-720 ) and Tungsten corona needle  824 . Also shown in  FIG. 8  is Aluminum Ground Ring Electrode  822 . This ring electrode is concentrically placed around the corona needle  824  and serves as a ground reference for the corona needle  824 . The tip geometry of the needle  824  in reference to the ground ring electrode  822  creates an inhomogeneous electric field due to the negative high voltage potential difference applied. This produces a breakdown of the atmosphere localized around the tip of the needle  824 . The PUPS unit  102  uses commercially available  7 B Tungsten probes from Micromanipulator to reduce fabrication cost.  FIG. 8 . also illustrates the spatial relationship of Corona Ionizer Housing  826  (See also  FIG. 7-726 ) and Aluminum Corona Needle Support  828 . This tri-spoke support  828  holds the corona needle in place and creates and electrical connection to the high voltage set screw and brass fitting (See also  FIG. 7-724 ). 
         [0045]    Referring also to  FIG. 9 , there is shown a pictorial illustration of the Corona Needle Support  902  (Conductive &amp; Non-Conductive; See  FIG. 8-828  &amp;  FIG. 10-1032 , respectively). Machined channels  938  provide the pathways through the structure of the corona needle support  936  for the aerosol to flow into the charging region of the corona ionizer (See  FIG. 7-702 ). These channels  938  align with the channels of the mating corona needle support  902  due to an alignment key on the side of the unit  902 . 
         [0046]    Referring also to  FIG. 10 , there is shown a pictorial illustration of the PTFE Teflon, Aluminum, and Tungsten Corona Ionizer Internal Assembly  1002 .  FIG. 10  further illustrates the spatial relationship of the Conductive Corona Needle Support  1028  (See also  FIG. 8-828 ), the Corona Needle  1030  (See also  FIG. 8-824 ), and the Electrical Grade PTFE Teflon Non-Conductive Corona Needle Support  1032 . The Non-Conductive Corona Needle Support  1032  holds the corona needle ( FIG. 8-824 ) in place and directs the aerosol flow around the localized atmospheric breakdown region occurring at the tip of the corona needle  1030 . The support  1032  serves as an insulator between the conductive corona needle support ( FIG. 8-828 ) and the ground ring electrode ( FIG. 8-822 ). Also, shown is Ground Ring Electrode  1036  (See also  FIG. 8-822  and Machined channel  1038  (See also  FIG. 9-938 ). 
         [0047]    Referring also to  FIG. 11 , there is shown a pictorial illustration of a cross section of the Corona Ionizer Internal Assembly  1102 . Also shown in  FIG. 11  are Conductive Corona Needle Support  1128  (See also  FIG. 8-828 ) and Ground Ring Electrode  1122  (See also  FIG. 8-822 ). 
         [0048]    Referring also to  FIG. 12 , there is shown a rotated illustrated view of the Corona Ionizer  1202  (See also  FIG. 7-702 ). Corona Ionizer Housing  1226  (See also  FIG. 7-726 ); Corona Needle  1230 —See also  FIG. 8-824 ; Non-Conductive Corona Needle Support  1232  (See also  FIG. 10-1032 ); and Ground Ring Electrode  1234  (See also  FIG. 8-822 ). 
         [0049]    Referring also to  FIG. 13 , there is shown a cross sectional illustration of flex-PCB inside rDMA housing  1302 . The flex-PCB (See also  FIG. 14-1402 ) is comprised of 3 sets of 8 pads that form ring electrodes  1340  when installed in the rDMA housing  1302 . Each of the Gold Plated Copper Flex-PCB Fabricated Ring Electrodes  1340  serves as a collector on which charged aerosol particles impact. Charge transferred from these charged particles induces a current which is directed to the detection circuitry shown in  FIG. 15 . 
         [0050]    Referring also to  FIG. 14 , there is shown an illustrated layout of the flexible Gold plated Copper on Flexible Substrate Printed Circuit Board  1402 . The flex-PCB  1402  comprises a series of electrodes for charge detection. The flex-PCB  1402  wraps around the inside of the reverse Differential Mobility Analyzer housing (rDMA) (See  FIG. 2-208 ) while the smaller traces create a current path to the detection circuitry (See  FIG. 15 ). It will be appreciated that the width and location of each electrode  1402  can be designed to select specific bands of particle sizes of interest. It will be further appreciated that flexible PCB electrodes  1402  with integrated electrometers allow for quick removal and cleaning, as well as inexpensive replacement. In addition, PCB electrodes  1402  minimize electrical noise in the measurements due to lowered capacitive effects of fixed electrodes  1402 . PCB electrodes  1402  incorporate inherent bi-polar junction transistors directly on the detection electrodes  1402 , allowing amplification at the charged particle impaction site  1402 . The use of printed or thin-film transistors as detection electrodes, as described herein, minimize electrical losses due to resistive materials and also eliminate electrical noise due to the dipole nature of transmission traces. The inherent nature of the PCB electrodes  1402  transistor provide current amplification at the source of charge transfer, therefore improving overall signal quality. 
         [0051]    Referring also to  FIG. 15 , there is shown a functional flow diagram  1502  of the PUPS detection circuitry and legend  1530   
         [0052]    Particle Size Selecting Components—This portion of the system is dedicated to discriminating particle size based on Electrical Mobility. Sample particles are charged in the corona ionizer  1510  and are then incident to electric field induced by high potential which affects the flight path of the particle in the rDMA  1508 . The through-device particle velocity is determined by the pump  1504  and proportional valve  1512  creating a closed-loop control system with the flow meter  1506 . 
         [0053]    Voltage Controllers—The first voltage controllers  1518  provide the requisite potential for breakdown in the corona ionizer  1510 . The second voltage controller  1516  provides the high potential needed to alter the course of the charged particles to impact on the electrode walls. 
         [0054]    Detection Circuitry—The detection circuitry contains the flexible printed circuit board (flex-PCB) electrodes  1514  which the charged particles impact and transfer their charge to as well as the low-current measurement circuitry (see legend  1530 ). It will be appreciated that any suitable low-current measurement circuitry may be used. The signal produced (which has been converted to a digital signal by converter  1520 ) contains information which can be processed to determine the time-resolved particle concentrations impacting the electrodes. 
         [0055]    Data Acquisition and Flow Control—The Data Acquisition section  1526  houses both Digital and Analog circuitry to monitor system components as well as control the high voltage sources. The Flow Control section  1522  controls the pump and flow rates of the instrument. 
         [0056]    Peripheral Devices—The peripheral devices associated with the instrument are optional to the primary objective of the device. In the figure, a Global Positioning System Receiver  1528  is shown allowing particle measurements to occur both in a temporal and spatial system. 
         [0057]    Still referring to  FIG. 15 , computer/microcontroller  1524  may be any suitable computer/microcontroller. For example, computer/microcontroller  1524  may be a “mote”. As used in this disclosure, the term “mote device” or “mote” typically indicates an autonomous or semi-autonomous computing, communication, actuating, and/or sensing device as described in the mote literature (e.g., Intel Corporation&#39;s, or Crossbow Inc.&#39;s mote literature). 
         [0058]    Certain embodiments of the mote device(s)  1524  can be fabricated to be relatively small (typically less than several inches in dimension, often a fraction of an inch). Certain embodiments of mote systems(s) (e.g., controller  1524  and data acquisition  1526 , GPS receiver  1528 ) can also be relatively inexpensive to produce, and can be designed to stand up to relatively harsh and/or external environments. 
         [0059]    Many embodiments of mote systems(s)  1524 , or simply “motes”, as described in this disclosure can provide a wide variety of parameter sensing and/or actuating functionalities. Such parameter sensing may be controlled (and/or light or display device actuated) using computer-based sensing, electro-mechanical sensing, magnetic sensing, and/or other sensing techniques. Certain embodiments of mote device(s) and networks can be located at remote, hostile, external, or inaccessible location(s); and can be wirelessly networked. 
         [0060]    Mote  1524  can be programmed with control algorithms for auxiliary circuitry managing activation of sources and sensors, to ensure that energy is expended in an efficient manner, and to dynamically adapt deployments to environmental conditions. 
         [0061]    Still referring to  FIG. 15  there is shown a programmable mote device  1524 , equipped with auxiliary processor  1524 A, RAM  1524 B and Flash memory  1524 C. Optionally, mote  1524  can be augmented with external memory  1524 D. Motes also have a communication device  1524 E capable of approximately  100  meter communication range, and can support a variety of data retrieval techniques. 
         [0062]    It will be appreciated that the invention advantageously incorporates motes  1524  to eliminate the wiring burdens and heavy enclosures often required of traditional data logging mechanisms, and significantly reduces power requirements. The mote system ( FIG. 15 , item  1524 ) establishes a standard protocol connection, for example, but not limited to, a TCP/IP connection with another mote system. This standard protocol allows an easy interface to data storage and visualization applications. Furthermore, this TCP/IP connection serves as an actuation channel, for controlling the deployment remotely, for example to modify sampling rates for power management. 
         [0063]    It will be appreciated that the invention overcomes prior art limitations with novel features such as: Particle Ionization Particles ionized in the PUPS receive a negative charge via a low cost unipolar corona ionizer. Defining features of the PUPS corona ionizer 
         [0064]    A pin-to-cylinder configuration is used giving the device rotational symmetry. 
         [0065]    A negative kilovolt DC potential sets up a static electric field from pin to cylinder. 
         [0066]    Low cost tungsten microprobes (normally used for semiconductor test applications) form the corona pin. The microprobes have very small tip geometry and tungsten is resistant to corrosion. 
         [0067]    A composite manifold made from virgin electrical grade Teflon® polytetrafluoroethylene (PTFE) and  6061  aluminum alloy serves the dual purpose of making electrical contact and channeling the aerosol around the corona avalanche head to reduce particle fragmentation. 
         [0068]    The body of the corona ionizer is constructed from PTFE due to its electrical and chemical resistance. 
         [0069]    Similarly, the advantageous features of the invention&#39;s Flexible PCB Detectors also overcome limitations in the prior an. The Flexible Printed Circuit Board (flexPCB) detectors are used for particle detection and allow a circuit to bend to fit geometries which normal printed circuit boards cannot. There are at least four major benefits to using flexPCBs as described in this invention description: 
         [0070]    The flexPCB can easily be removed for cleaning, whereas fixed-ring designs require difficult cleaning procedures which do not ensure complete cleanliness. 
         [0071]    Disposable electrodes can be built due to the relative low cost of the flexPCB. 
         [0072]    The flexPCB can be removed from the DMA allowing chemical samples to be taken based on specific size-bands of particles contacting the electrodes. 
         [0073]    The flexPCB makes it possible to place the electrometer circuit on the electrode itself, thus minimizing signal losses. 
         [0074]    It should be understood that the foregoing description is only illustrative of the invention. For example, the PUPS may use a positive corona ionizer for applying a positive charge via a positive high voltage potential to the aerosol particles with suitable modifications to the PUPS rDMA and detection circuitry. Thus, various alternatives and modifications can be devised by those skilled in the art without departing from the invention. For example, the portability of the invention stemming from the light weight and small size of the present invention (approximately 432 cu. in. and approximately 8 lbs, respectively) may be modified slightly. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.