AEROSOL EXPOSURE MONITORING

• US 20140347663A1
• Filed: 10/26/2012
• Published: 11/27/2014
• Est. Priority Date: 10/26/2011
• Status: Active Grant

• Current Assignee: Research Triangle Institute
• Original Assignee: Research Triangle Institute
• Inventors: Rodes, Charles E., Newsome, J. Randall
• Granted Patent: US 9,304,117 B2
• Time in Patent Office: Days
• US Class Current: 356/338
• CPC Class Codes: G01N 1/2273 Atmospheric sampling
• CPC Class Codes: G01N 15/0255 with mechanical, e.g. inertial, classification, and investigation of sorted collections with centrifuges G01N15/042
• CPC Class Codes: G01N 21/51 inside a container, e.g. in an ampoule G01N21/53 takes precedence
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G01N 33/0016 by regulating a physical variable, e.g. pressure, temperature
• CPC Class Codes: G01N 33/0027 concerning the detector

Abstract

A gas processing device such as an aerosol exposure monitor is configured for acquiring chronic data, acute data, or both simultaneously, and may include a pump and a noise dampening device. The noise dampening device may include an elastomeric membrane between an inlet chamber and an outlet chamber. In another aspect, an aerosol exposure monitor may include an impactor, a collection filter, and a nephelometer that includes a sample chamber integrated with an aerosol flow path associated with the impactor and collection filter.

Claims

1. An aerosol exposure monitor, comprising:

an impactor;

a sample chamber communicating with the impactors and defining a laminar fluid flow path along a first axis;

a collection filter communicating with the sample chamber and removable from the aerosol exposure monitor;

a pump communicating with the collection filter;

a light source;

a light detector;

a first bore defining a first optical path from the light source to the sample chamber along a second axis; and

a second bore defining a second optical path from the sample chamber to the light detector along a third axis, wherein the first axis, the second axis and the third axis are at angles to each other.

2. The aerosol exposure monitor of claim 1, comprising at least one of the following:

a sample inlet comprising an inlet opening configured such that the sample inlet establishes an inlet flow path that turns ninety degrees from the inlet opening to the impactor;

a light trap disposed on a side of the sample chamber opposite to the first bore;

an accelerometer configured for detecting motion of the aerosol exposure monitor along one or more axes;

a differential pressure sensor configured for detecting a pressure drop across an orifice between the collection filter and the pump;

a differential pressure sensor configured for detecting a pressure drop between an inlet side of the impactor and an outlet side of the collection filter.

3. The aerosol exposure monitor of claim 1, wherein the impactor comprises a plurality of impactor stages, each successive impactor stage having a smaller cut-point than the other impactor stages.

4. The aerosol exposure monitor of claim 1, wherein the sample chamber has a length between the impactor and the collection filter ranging from 20 mm to 22 mm, and a cross-sectional dimension ranging from 9 mm to 14.5 mm.

5. The aerosol exposure monitor of claim 1, wherein the pump is configured for providing a flow rate ranging from 0.30 to 0.60 liters per minute.

6. The aerosol exposure monitor of claim 1, wherein the light source is configured according to at least one of the following:

the light source is configured for generating a light beam having a cylindrical sensing volume;

the light source is configured for generating a light beam having a cylindrical sensing volume in the sample chamber, and the cylindrical sensing volume has a length ranging from 8.0 to 12.0 mm and a diameter ranging from 0.5 to 2.0 mm;

the light source is configured for generating a light beam having a cylindrical sensing volume, wherein the sensing volume is an elliptic cylinder.

9. The aerosol exposure monitor of claim 1, wherein the light detector comprises a rectilinear sensing area communicating with the second bore.

13. The aerosol exposure monitor of claim 1, comprising circuitry configured according to at least one of the following:

circuitry configured for collecting quality control data during operation of the aerosol exposure monitor;

circuitry configured for collecting quality control data during operation of the aerosol exposure monitor, wherein the quality control data are selected from the group consisting of a flow rate of fluid through the collection filter, a pressure drop through the collection filter, a pressure drop from an inlet side of the impactor to an outlet side of the collection filter, a temperature of fluid flowing through the aerosol exposure monitor, a relative humidity of fluid flowing through the aerosol exposure monitor, data produced by an accelerometer of the aerosol exposure monitor defining wearing compliance, a voltage level of a battery of the aerosol exposure monitor, GPS data pertaining to a location of the aerosol exposure monitor, and a combination of two or more of the foregoing;

circuitry configured for adjusting the pump based on a parameter selected from the group consisting of a flow rate of fluid through the collection filter, a pressure drop across an orifice following the collection filter, a pressure drop from an inlet side of the impactor to an outlet side of the collection filter, a temperature of fluid flowing through the aerosol exposure monitor, a relative humidity of fluid flowing through the aerosol exposure monitor, and a combination of two or more of the foregoing.

16. The aerosol exposure monitor of claim 1, comprising at least one of the following:

a noise dampening device communicating with the pump;

a noise dampening device communicating with the pump, wherein the noise dampening device comprises an inlet chamber, an outlet chamber, and an elastomeric membrane interposed between and fluidly isolating the inlet chamber and the outlet chamber, wherein the inlet chamber is interposed between the collection filter and the pump inlet, and the outlet chamber communicates with the pump outlet.

7-8. -8. (canceled)

10-12. -12. (canceled)

14-15. -15. (canceled)

17. (canceled)

18. A gas processing device, comprising:

a housing;

a sample inlet defining a gas flow path into the housing;

a pump disposed in the housing and comprising a pump inlet and a pump outlet; and

a noise dampening device disposed in the housing and comprising an inlet chamber, an outlet chamber, and an elastomeric membrane interposed between and fluidly isolating the inlet chamber and the outlet chamber, wherein the inlet chamber is interposed between the sample inlet and the pump inlet, and the outlet chamber communicates with the pump outlet.

19. The gas processing device of claim 18, comprising at least one of the following:

wherein the noise dampening device comprises an exhaust tube communicating with the outlet chamber, and the outlet chamber is interposed between the pump outlet and the exhaust tube;

wherein the noise dampening device comprises an exhaust tube communicating with the outlet chamber, and the outlet chamber is interposed between the pump outlet and the exhaust tube, and wherein the exhaust tube has a length ranging from 1 to 15 cm;

wherein the noise dampening device comprises an exhaust tube communicating with the outlet chamber, and the outlet chamber is interposed between the pump outlet and the exhaust tube, and wherein the exhaust tube terminates in an interior of the housing.

22. The gas processing device of claim 18, wherein the inlet chamber comprises a first port communicating with the sample inlet and a second port communicating with the pump inlet, and the outlet chamber comprises a third port communicating with the pump outlet and a fourth port communicating with a region outside the noise dampening device.

23. The gas processing device of claim 22, comprising at least one of the following:

wherein the first port, the second port, the third port and the fourth port are arranged such that gas flow through the inlet chamber is counter to gas flow through the outlet chamber;

wherein the first port and the second port are oriented at an angle to each other such that the inlet chamber establishes a gas flow path that includes a change in direction, and the third port and the fourth port are oriented at an angle to each other such that the outlet chamber establishes a gas flow path that includes a change in direction.

20-21. -21. (canceled)

24-31. -31. (canceled)

32. A method for monitoring aerosol, the method comprising:

sizing particles of the aerosol by flowing the aerosol through sequential impactors;

collecting the sized particles by flowing the aerosol through a sample chamber along a first axis and through a collection filter, wherein the sized particles are collected on the collection filter, and wherein flowing the aerosol through the impactors, the sample chamber and the collection filter comprises operating a pump communicating with an outlet side of the collection filter;

irradiating the sized particles flowing through the sample chamber by directing an irradiating light into the sample chamber along a second axis angled relative to the first axis, wherein scattered light propagates from the irradiated particles; and

directing the scattered light to a light detector along a third axis angled relative to the first axis and the second axis to sense a total scattering potential of the sized particles.

33. The method of claim 32, comprising at least one of the following:

wherein the flow of aerosol out from the impactors, through the sample chamber, and to the collection filter is substantially laminar;

wherein the aerosol is flowed through the collection filter at a total system pressure drop through the collection filter of 2 inches H₂O or less;

wherein the aerosol is flowed through the collection filter at a flow rate ranging from 0.30 to 0.60 liters/min.

36. The method of claim 32, wherein directing the irradiating light into the sample chamber comprises at least one of the following:

establishing a cylindrical sending volume of light in the sample chamber;

establishing a cylindrical sensing volume of light in the sample chamber, and the cylindrical sensing volume has a length ranging from 8.0 to 12.0 mm and a cross-sectional dimension ranging from 0.5 to 2.0 mm;

establishing a cylindrical sensing volume of light in the sample chamber, wherein the cylindrical sensing volume has an elliptical cross-section and the cross-sectional dimension is a major axis.

38. The method of claim 32, wherein directing the scattered light to the light detector comprises directing the scattered light from the sample chamber as a beam having a rectilinear cross-section.

39. The method of claim 32, comprising acquiring particle concentration data from the light detector, and subjecting the collection filter to a particle analysis.

40. The method of claim 32, comprising at least one of the following:

operating an aerosol exposure monitor to size the particles, collect the sized particles, irradiate the sized particles and direct the scattered light, while a user is wearing the aerosol exposure monitor;

operating an aerosol exposure monitor to size the particles, collect the sized particles, irradiate the sized particles and direct the scattered light, while a user is wearing the aerosol exposure monitor, and acquiring accelerometer data corresponding to movement of the user while wearing the aerosol exposure monitor to provide an indication of activity of the user during wearing of the aerosol exposure monitor near a breathing zone of the user;

operating an aerosol exposure monitor to size the particles, collect the sized particles, irradiate the sized particles and direct the scattered light, while a user is wearing the aerosol exposure monitor, and acquiring accelerometer data corresponding to movement of the user while wearing the aerosol exposure monitor to provide an indication of activity of the user during wearing of the aerosol exposure monitor near a breathing zone of the user, and calculating a ventilation rate (m³/min) of the user during wearing of the aerosol exposure monitor based on the accelerometer data, calculating a potential dose (μ

g/min/kg) of the user during wearing of the aerosol exposure monitor based on the accelerometer data and on particle concentration data acquired from the light detector, or calculating both the ventilation rate and the potential dose.

34-35. -35. (canceled)

37. (canceled)

41-42. -42. (canceled)

43. A method for monitoring aerosol, the method comprising:

operating a pump to establish a flow of aerosol into a housing and to a collection filter disposed in the housing, wherein aerosol particles of a desired size range are collected on the collection filter and gas from the aerosol flows through the collection filter;

flowing the gas from an outlet side of the collection filter, through an inlet chamber, and into an inlet of the pump; and

flowing the gas from an outlet of the pump, through an outlet chamber, and through an exhaust port open to a region outside the outlet chamber, wherein the outlet chamber is adjacent to the inlet chamber and an elastomeric membrane is interposed between and fluidly isolates the inlet chamber and the outlet chamber,

wherein the gas flowing through the inlet chamber contacts a first side of the elastomeric membrane, and the gas flowing through the outlet chamber simultaneously contacts a second side of the elastomeric membrane, and noise associated with the respective flows of the gas through the inlet chamber and the outlet chamber is reduced.

44. The method of claim 43, comprising flowing the gas through an exhaust tube connected to the exhaust port, wherein the exhaust tube has a length ranging from 1.0 to 15.0 cm.

45. The method of claim 43, wherein the gas flows through the inlet chamber in a direction opposite to the gas flowing through the outlet chamber.

46. The method of claim 43, wherein the gas flows into the inlet chamber through a first port, out from the inlet chamber through a second port, into the outlet chamber through a third port and out from the inlet chamber through the exhaust port, the flow of gas through the inlet chamber changes direction between the first port and the second port, and the flow of gas through the outlet chamber changes direction between the third port and the fourth port.

47-49. -49. (canceled)