阅读说明：本技术 颗粒物传感器 (Particulate matter sensor ) 是由 哈拉尔德.埃奇迈尔 巴萨姆.哈拉儿 伊丽莎.帕罗拉 乔治.罗勒 于 2018-12-13 设计创作，主要内容包括：一种颗粒物传感器模块包括安装在基板上的光源和光检测器。壳体附接到基板,并且包括在基板上堆叠地彼此附接的第一部分和第二部分,使得第一部分设置在基板和第二部分之间。第一部分和第二部分组合限定光反射室、流体流动导管、颗粒-光相互作用室和光阱室。第一部分具有第一孔,由光源发射的光可以通过该第一孔到达光反射室内的反射表面。反射表面被配置成将光朝向颗粒-光相互作用室反射,在颗粒-光相互作用室处光可以与在流体流动导管中流动的流体中的颗粒相互作用。第一部分具有第二孔,由于与一个或多个颗粒的相互作用而在颗粒-光相互作用室中散射的光可以通过该第二孔以被检测器感测。流体流动导管包括流体入口部分,该流体入口部分具有直接耦合到颗粒-光相互作用室的端部。(A particulate matter sensor module includes a light source and a light detector mounted on a substrate. The housing is attached to the substrate and includes a first portion and a second portion that are attached to each other in a stacked relation on the substrate such that the first portion is disposed between the substrate and the second portion. The first portion and the second portion in combination define a light reflecting chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trapping chamber. The first portion has a first aperture through which light emitted by the light source may pass to a reflective surface within the light reflective chamber. The reflective surface is configured to reflect light toward a particle-light interaction chamber where the light can interact with particles in a fluid flowing in the fluid flow conduit. The first portion has a second aperture through which light scattered in the particle-light interaction chamber due to interaction with one or more particles can pass to be sensed by the detector. The fluid flow conduit includes a fluid inlet portion having an end directly coupled to the particle-light interaction chamber.)

1. A particulate matter sensor module comprising:

a light source and a light detector mounted on the substrate;

a housing attached to the substrate and comprising a first portion and a second portion attached to one another in a stack on the substrate such that the first portion is disposed between the substrate and the second portion, wherein the first portion and the second portion in combination define a light reflection chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trap chamber,

the first portion having a first aperture through which light emitted by the light source can pass to a reflective surface within a light reflective chamber, the reflective surface configured to reflect the light towards the particle-light interaction chamber where the light can interact with particles in a fluid flowing in the fluid flow conduit,

the first portion having a second aperture through which light scattered in the particle-light interaction chamber due to interaction with one or more particles can pass to be sensed by the detector,

wherein the fluid flow conduit comprises a fluid inlet portion having an end directly coupled to the particle-light interaction chamber.

2. The module of claim 1, wherein the particle-light interaction chamber has a cross-section that widens along an axis parallel to a beam path between the reflective surface and the optical trap chamber.

3. The module of claim 2, wherein the cross-section widens in a direction toward the optical trap chamber.

4. The module of claim 2, wherein the cross-section widens in a direction toward the reflective surface.

5. The module of claim 2, wherein the particle-light interaction chamber has a tapered inner wall.

6. The module of claim 5, wherein an end of the fluid inlet portion is directly coupled to one of the tapered inner walls.

7. The module of any one of claims 1-6, wherein the particle-light interaction chamber has a tapered inner wall that widens in a direction toward the detector.

8. The module of any one of claims 1-7, wherein the reflective surface is a surface of the second portion of the housing.

9. The module of any one of claims 1-7, wherein the reflective surface is a surface of the first portion of the housing.

10. The module of any of claims 1-7, wherein the reflective surface is a surface of a component disposed on a surface of the first portion of the housing.

11. The module of claim 1, wherein each of the first and second portions of the housing is comprised of an injection molded material.

12. The module of claim 1, wherein each of the first and second portions of the housing are constructed of a plastic material.

13. The module of any one of claims 1-12, wherein the combination of the first portion and the second portion further defines a barrier between the light-reflective chamber and the particle-light interaction chamber, wherein the barrier has an aperture through which light reflected by the reflective surface can pass.

14. The module of claim 13, wherein the bulkhead comprises:

a first wall projecting from a first portion of the housing toward a second portion of the housing; and

a second wall protruding from the second portion of the housing toward the first portion of the housing, wherein the second wall is attached to the first portion of the housing by an adhesive;

wherein each of the first and second walls has a respective opening, and wherein overlapping portions of the openings define the aperture through which light reflected by the reflective surface can pass.

15. The module of claim 14, wherein the first wall is closer to the light reflecting chamber than the second wall.

16. The module of claim 14, wherein the first wall is disposed to block light reflected by the reflective surface from passing through the adhesive at a location where the second wall is attached to the first portion of the housing.

17. The module of claim 1, wherein the inner surfaces of the first and second portions have a coating comprised of a low reflectivity material.

18. The module of claim 1, wherein the inner surfaces of the first and second portions have a coating comprised of a black material.

19. The module of any of claims 17-18, comprising an adhesive bonding the first and second portions of the housing together, wherein a majority of the adhesive is not visible from within the light trapping chamber.

20. The module of any one of claims 1-19, further comprising a waveguide that directs scattered light to the light detector.

21. The module of any one of claims 1-20, further comprising a second light detector mounted on the substrate and operable to monitor optical power emitted from the light source.

22. A mobile computing device, comprising:

a particulate matter sensor system comprising the particulate matter sensor module according to any one of claims 1-21;

an application capable of running on a mobile computing device and operable to conduct an air quality test; and

a display screen operable to display a test result of the application.

23. A method of manufacturing a particulate matter sensor module, the method comprising:

attaching a first portion of a housing to a substrate on which a light source and a light detector are mounted, wherein the first portion has a first aperture through which light emitted by the light source can pass;

attaching a second portion of the housing to the first portion such that the first portion is disposed between the substrate and the second portion,

wherein the first portion and the second portion in combination define a light reflecting chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trapping chamber.

24. The method of claim 23, further comprising placing an assembly on a surface of a first portion of the housing, the assembly having a reflective surface operable to reflect from the light source toward the particle-light interaction chamber, wherein placing the assembly is performed prior to attaching the second portion of the housing to the first portion.

25. The method of any of claims 23-24, comprising forming each of the first and second portions of the housing using an injection molding technique.

26. The method of any of claims 23-25, wherein each of the first portion and the second portion has a respective alignment feature, the method comprising:

engaging the alignment feature of the first portion with the alignment feature of the second portion; and

the first and second parts are then attached to each other in a permanent manner.

27. The method of any of claims 23-26, wherein attaching a first portion of the housing to a substrate and attaching a second portion of the housing to the first portion are part of a wafer level fabrication process.

Technical Field

The present disclosure relates to particulate matter sensors.

Background

For example, various forms of combustion, chemical processes, or mechanical wear can produce airborne particulates. The size of the particles varies over a wide range, with some particles settling rapidly in still air, while smaller particles may remain suspended for longer periods of time. Exposure to particulate matter can be harmful to human health. In addition, some particles act as abrasives or contaminants and can interfere with the performance of the equipment.

Some techniques for measuring the presence, quantity and/or size of particulate matter in air rely on optical techniques in which particles are illuminated with optical signals and light scattered by the particles is detected.

Disclosure of Invention

The present disclosure describes a particulate matter sensor module that operates based on sensing light scattered by particulate matter. Compact particulate matter sensor modules are generally required to be able to analyze all or at least most of the pumped fluid; otherwise, the available number of particles to be counted and/or the size of the particles to be sorted may be too small to be determined within a reasonable measurement time. In some embodiments, the modules described in this disclosure can achieve this desired result by focusing the fluid to be measured into a small area where interaction with light occurs.

In one aspect, for example, a particulate matter sensor module includes a light source and a light detector mounted on a substrate. The housing is attached to the substrate and includes a first portion and a second portion that are attached to each other in a stacked relation on the substrate such that the first portion is disposed between the substrate and the second portion. The first portion and the second portion in combination define a light reflecting chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trapping chamber. The first portion has a first aperture through which light emitted by the light source may pass to a reflective surface within the light reflective chamber. The reflective surface is configured to reflect light toward a particle-light interaction chamber where the light can interact with particles in a fluid flowing in the fluid flow conduit. The first portion has a second aperture through which light scattered in the particle-light interaction chamber due to interaction with one or more particles can pass to be sensed by the detector. The fluid flow conduit includes a fluid inlet portion having an end directly coupled to the particle-light interaction chamber.

Some implementations include one or more of the following features. For example, in some cases, the particle-light interaction chamber has a cross-section that widens along an axis parallel to the beam path between the reflective surface and the light trapping chamber. The inner wall of the particle-light interaction chamber may for example be conical. In some cases, the cross-section widens in a direction toward the optical trap chamber, while in other cases, the cross-section widens in a direction toward the reflective surface. Furthermore, in some embodiments, the particle-light interaction chamber has a tapered inner wall that widens in a direction towards the detector.

In some embodiments, an end of the fluid inlet portion is directly coupled to one of the tapered inner walls.

In some cases, the reflective surface is a surface of the second portion of the housing, while in other cases, the reflective surface is a surface of the first portion of the housing. The reflective surface may be, for example, a surface of a component disposed on a surface of the first portion of the housing.

In some embodiments, each of the first and second portions of the housing is constructed of an injection molded material. Each of the first and second portions of the housing may be constructed of, for example, a plastic material.

The combination of the first portion and the second portion may also define a barrier between the light-reflecting chamber and the particle-light interaction chamber, wherein the barrier has an aperture through which light reflected by the reflective surface can pass. In some embodiments, the partition includes a first wall protruding from the first portion of the housing toward the second portion of the housing, and a second wall protruding from the second portion of the housing toward the first portion of the housing. The second wall may be attached to the first portion of the housing by an adhesive. Each of the first and second walls may have a respective opening, wherein overlapping portions of the openings define an aperture through which light reflected by the reflective surface can pass. In some cases, the first wall is closer to the light reflecting chamber than the second wall. The first wall may be arranged to block light reflected by the reflective surface from passing through the adhesive at a location where the second wall is attached to the first portion of the housing.

In some cases, the inner surfaces of the first and second portions of the housing have a coating comprised of a low reflectivity material. The module may further include an adhesive bonding the first and second portions of the housing together, wherein a majority of the adhesive is not visible from within the light trapping chamber.

In some embodiments, the module includes a waveguide that directs the scattered light to the light detector. Also, in some cases, the module includes a second light detector mounted on the substrate and operable to monitor optical power emitted from the light source.

The present disclosure also describes a mobile computing device (e.g., a smartphone) that includes a particulate matter sensor system that includes a particulate matter sensor module, an application that is capable of running on the mobile computing device and that is operable to conduct an air quality test, and a display screen that is operable to display test results of the application.

The present disclosure further describes a method of manufacturing a particulate matter sensor module. The method includes attaching a first portion of a housing to a substrate on which the light source and the light detector are mounted, and attaching a second portion of the housing to the first portion such that the first portion is disposed between the substrate and the second portion. The first portion has a first aperture through which light emitted by the light source may pass. The first portion and the second portion in combination define a light reflecting chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trapping chamber.

Some implementations include one or more of the following advantages. For example, by forming the fluid inlet portion of the fluid flow conduit and the particle-light interaction chamber as a single component, the distance between them need not be dependent on mechanical alignment tolerances. Furthermore, the spacing between the fluid inlet portion and the optical path may be relatively small. By bringing the fluid inlet portion of the fluid flow conduit very close to the optical path, which is desirable to achieve good focusing of the fluid in the relevant region, in some cases the support conduit material may shield part of the optical signal. However, this effect may be reduced by tapered sidewall(s) in the particle-light interaction chamber (e.g., tapering towards the detector).

The tapered shape of the chamber (e.g., tapering along an axis from the reflective surface toward the optical trap) may be designed such that even if the light beam diverges, the light beam does not impinge on the sidewalls of the particle-light interaction chamber, including the fluid inlet portion of the fluid flow conduit.

Other aspects, features and advantages will be apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

Fig. 1 schematically shows a particle sensor module.

FIG. 2 shows an exploded top perspective view of a first example of a housing for a particulate matter sensor module.

FIG. 3 shows an exploded bottom perspective view of a first example of a housing for a particulate matter sensor module.

FIG. 4 is a cross-section of another example of a housing of the particulate matter sensor module as viewed from the direction of the fluid outlet portion of the fluid flow conduit.

Fig. 5 is a cross-section of the housing of the module of fig. 4.

FIG. 6A shows a cross-sectional view of a portion of a baffle containing an aperture for an optical path.

Fig. 6B is a cross-sectional view of fig. 6A.

Fig. 6C shows the relative positions of the various surfaces in fig. 6A and 6B.

FIG. 7 shows an example of a method of manufacturing a particulate matter sensor module.

FIG. 8 illustrates an example of a mobile or handheld computing system that includes a particulate matter sensor system.

Detailed Description

As shown in fig. 1, the particulate matter sensor module 20 includes a light source 22 (e.g., a Vertical Cavity Surface Emitting Laser (VCSEL)) operable to emit light toward the reflective surface 28, the reflective surface 28 redirecting the emitted light along a path 30 through one or more light apertures 34A, 34B such that the light path 30 passes through a particle-light interaction chamber 40. A fluid (e.g., aerosol) is pumped through the fluid flow conduit 32, and the fluid flow conduit 32 may be substantially perpendicular to the optical path 30. Thus, in the illustrated example, the optical path 30 is in the x-direction and the fluid flow conduit 32 is in the z-direction. As the fluid flows through the conduit 32, the light beam interacts with particulate matter in the fluid in the particle-light interaction chamber 40. This interaction scatters some of the light toward a light detector 24 (e.g., a photodiode), which light detector 24 is operable to detect the scattered light. In some embodiments, as shown in FIG. 1, a light pipe or other waveguide 42 may be provided to direct scattered light to the light detector 24 and reduce the effective distance from the particle-light interaction chamber 40 to the detector 24. Light that does not interact with the particular species continues into the optical trap chamber 36 to prevent such light from being reflected back to the detector 24.

The detector 24 may be implemented, for example, as an optical photosensor operable to measure the signal of individual particles. In this case, the pulse height is proportional to the particle size, and the pulse count rate corresponds to the number of particles detected. If the amount of the analysis volume is known (e.g. air flow rate, measurement time), the concentration may be derived, for example, from the number of particles detected. The mass can be calculated based on the assumed refractive index and density. In other embodiments, detector 24 is implemented as a photometer or turbidimeter. The detector 24 may be integrated, for example, into a semiconductor chip, which may also include electronics for reading, amplifying and processing the signal. In some cases, the processing circuitry may reside in a separate chip. The light source 22 and the detector 24 may be mounted on and electrically connected to a substrate 26 (e.g., a printed circuit board).

In some embodiments, the second light detector 44 may be mounted on the substrate and may be used to monitor the optical power emitted from the light source 22. The second detector 44 may be placed, for example, beside the light source or below an aperture in the optical trapping chamber 36.

Fig. 2 and 3 illustrate various aspects of a particulate matter sensor module 20A according to some embodiments. In the illustrated example, the module includes a housing 60, and the housing 60 may be attached over a substrate 26, with the light source 22 and detector 24 mounted on the substrate 26. The housing 60 has a lower portion 100 and an upper portion 102 that are attached to each other, for example, by adhesive. Each of the lower portion 100 and the upper portion 102 may be composed of, for example, plastic or resin, and may be formed, for example, by injection molding. The inner surfaces of the first and second portions may be coated, for example, with black or other low reflectivity material to reduce optical cross-talk and unwanted reflections. When attached together, the lower and upper sections combine to define a beam path 30 that includes apertures 34A, 34B and fluid flow conduit 32, particle-light interaction chamber 40, and light trapping chamber 36. Specifically, the lower portion 100 has a cavity 36A defining a first (lower) portion of the optical trap chamber 36, and the upper portion 102 has a cavity 36B defining a corresponding second (upper) portion of the optical trap chamber 36. The interior surfaces of the cavities 36A, 36B that define the trap chamber should be capable of absorbing most or all of the light that enters the trap chamber. The lower portion 100 also has a semi-conical recess 32A defining a first (lower) portion of the fluid flow conduit 32 and the upper portion 102 has a semi-conical recess 32B defining a second (upper) portion of the fluid flow conduit 32.

As further shown in fig. 2 and 3, the lower portion 100 has a first aperture 104 that is aligned with the light source optical axis (not shown in fig. 2 and 3) and also aligned with the reflective surface 28. The reflective surface 28 is disposed in a light reflective chamber defined by a cavity 29B in the upper portion 102 and a corresponding cavity 29A in the lower portion 100 of the housing. Thus, the combination of the lower portion 100 and the upper portion 102 of the housing 60 also defines a light reflecting chamber. Light emitted by the light source passes through the aperture 104 toward the reflective surface 28 (which is located in the upper portion 102 in the embodiment of fig. 2 and 3). The reflective surface 28 may be implemented as a reflective coating on a mirror or prism-shaped structure, for example. The reflective surface 28 is oriented to redirect the light beam through the apertures 34A, 34B and into the particle-light interaction chamber 40 where the light beam intersects the fluid flow through the conduit 32 and can interact with particulate matter in the fluid. The lower portion 100 also has a second aperture 106 that is aligned with the optical axis (not shown in fig. 2 and 3) of the light detector 24. Light scattered by the particulate matter may pass through the aperture 106 to be sensed by the detector 24.

The fluid flow conduit 32 includes a fluid inlet portion 110 that directs fluid into the particle-light interaction chamber 40, and a fluid outlet portion 112 that directs fluid out of the particle-light interaction chamber 40.

As described above, the axis of the fluid flow conduit 32 (i.e., the direction of fluid flow) is substantially perpendicular (transverse) to the optical path 30 from the reflective surface 28 to the particle-light interaction chamber 40. Preferably, the end of the inlet portion 110 from which the fluid enters the chamber 40 is coupled directly to the chamber 40 so that the end of the inlet portion 110 is as close as possible to the path of the light beam without interfering with the light beam. Placing the end of the inlet portion 110 very close to the optical path may help achieve good focusing of the fluid in the desired area. However, the inlet portion 110 should preferably not extend into the chamber 40 or into the path of the light beam 30. The fluid outlet portion 112 may also have an end that is directly coupled to the chamber 40. Here too, the exit portion 112 should preferably not extend into the chamber 40 or into the path of the light beam 30.

As shown in fig. 3, the particle-light interaction region chamber 40 may be implemented as a tapered structure having one or more tapered inner walls that widen slightly in the direction of the light trapping chamber 36. The tapered shape of chamber 40 may be designed to increase the likelihood of: even if the beam diverges as it travels in the direction of the optical trap chamber 36, the beam does not impinge on the side walls of the chamber 40, including the fluid inlet portion 110 or the fluid outlet portion 112 of the fluid flow conduit 32. In some embodiments, the tapered shape may allow for a narrower spacing from the inlet portion 110 of the fluid flow conduit 32 to the chamber 40. Where a beam shaping system (e.g., one or more optical lenses) is provided along the optical path 30 (e.g., between the reflective surface 28 and the chamber 40) to cause the light to converge, the walls of the chamber 40 may be designed to taper in the opposite direction (i.e., to narrow slightly in the direction of the optical trapping chamber 36).

In some embodiments, the interior walls of particle-light interaction region chamber 40 may also be tapered such that they widen slightly in a downward direction toward detector 24. The tapered shape may increase the likelihood that a greater percentage (or even all) of the light scattered due to light-particle interactions reaches detector 24.

By forming the lower portion 100 and the upper portion 102 of the housing 60, such as by injection molding, the fluid flow conduit 32 and the particle-light interaction chamber 40 may be formed as a single, integral piece such that the distance between them is not dependent on mechanical alignment tolerances. Further, in some cases, the overall height of the module may be on the order of only a few millimeters (e.g., 2 mm). Other dimensions may be suitable for some embodiments. Such a compact particle sensor module can help focus the fluid to be measured into a small area where interaction with light occurs, so that all or at least a majority of the pumped fluid (e.g., aerosol) can be analyzed in a reasonable measurement time.

FIG. 4 shows another example of a particulate matter sensor module 20B, which is similar in many respects to module 20A described above. However, in the module 20B of fig. 4, the reflective surface 28 is part of an assembly 200, which assembly 200 rests on a surface 202 of the lower portion 100 of the housing, rather than being attached to or part of the upper portion 102 of the housing as in fig. 2 and 3. The arrangement of fig. 4 may in some cases make it easier to align the reflective surface 28 with the light source 22 by utilizing the presence of the aperture 104 in the lower portion 100 during alignment.

Fig. 5 shows the cross-section of fig. 4 with the fluid inlet portion 112A of the fluid flow conduit 32 narrowing (e.g., conically) in the direction of the particle-light interaction chamber 40. On the other hand, the fluid outlet portion 110A of the fluid flow conduit 32 widens (e.g., conically) in a direction away from the particle-light interaction chamber 40. The presence of the fluid outlet portion 110A of the fluid flow conduit 32 may be particularly advantageous, for example, when the sensor 20B operates with a diaphragm pump to smooth fluid flow. As further shown in fig. 5, in addition to tapering the inner walls of the fluid inlet portion 112A and/or the fluid outlet portion 110A, the inner walls 46 of the particle-light interaction region chamber 40 may also be tapered such that they widen slightly in a downward direction toward the detector 24. The tapered shape allows most or even all of the light scattered to the detector to reach the detector, as is the case when there is a large distance between the walls (e.g., larger than the detector size).

Figure 4 also shows that in some cases, the lower portion 100 may have male and female alignment features 206, which alignment features 206 engage with corresponding male and female alignment features 208 of the upper portion 102. The respective alignment features 206, 208 may facilitate alignment of the two portions 100, 102 of the housing 60 before they are permanently attached to one another (e.g., by an adhesive). Thus, the alignment features 206, 208 may help ensure that the portions 100, 102 of the housing can be mounted together with minimal mechanically defined misalignment. Furthermore, the inner surfaces of the light trap chamber 36 may advantageously be coated with a low reflectivity (e.g., black) material. Preferably, the low-reflectance material has a reflectance of 1% or less. Glue or other adhesive 209 may be placed on the uppermost surface of the second portion 102, for example. Thus, much (or most) of the adhesive is not visible from the interior of the optical trap chamber 36, which may improve the quality and efficiency of the optical trap. Although a small portion of the adhesive is visible from within the optical trap chamber near the aperture at the entrance to the optical trap, the light reflected there typically requires multiple reflections before it can pass through the aperture and reach the detector.

As described below, a light-tight arrangement may be provided to form the baffles 210, 212 containing the apertures 34A, 34B for passage of the light beams. For ease of understanding, fig. 6A shows a view (viewed from the direction of the reflection surface 28) of a portion of the partition 210 in which the hole 34A is formed. Arrow 214 represents the direction of travel of the light beam after reflection by reflective surface 28. Fig. 6B shows a cross-sectional view of fig. 6A in a plane through the optical axis, parallel to the light beam and perpendicular to the aerosol flow. The partition 210 containing the hole 34A may constitute a double wall, a portion of which is formed by an upward projection 210A from the lower part 100 of the housing and a portion of which is formed by a downward projection 210B from the upper part 102 of the housing. The lower end 220 of the downward protrusion 210B may be attached to a flange (ridge) 224 adjacent to the upward protrusion 210A by an adhesive 222. Line 226 in fig. 6B represents the relative position of the top of hole 34A. Fig. 6C shows the relative positions of the various surfaces of the baffle 210 (from the perspective of the beams traveling toward the walls 210A, 210B). The overlapping portions of the openings in the upwardly and downwardly projecting walls 210A, 210B define the aperture 34A. In fig. 6C, a dotted line indicates a surface behind the protrusion 210A. The additional surfaces 230, 232, 234 of the lower part 100 and the additional surfaces 240, 242 of the upper part 102 are marked to facilitate comparison of figures 6A, 6B and 6C.

By using the arrangement from fig. 6A to 6C, the upward protrusion 210A can prevent the light beam from impinging on the adhesive 222 at the boundary where the lower part 100 and the upper part 102 of the housing are attached to each other. Thus, even if the adhesive 222 is transparent to the light beam, the light beam can only pass through the hole 34A in the partition 210. Also, even if there is a small vertical gap between the end 220 of the protrusion 210B and the flange 224 (e.g., due to manufacturing tolerances), the light beam will only pass through the hole 34A in the baffle 210. A similar arrangement may be provided for the baffle 212 containing the second aperture 34B. The features described in connection with fig. 6A to 6C may also be incorporated into the embodiments of fig. 2 and 3.

As shown in fig. 7, to manufacture one of the aforementioned modules 20A or 20B, each portion 100, 102(300) of the housing 60 is manufactured separately, for example using injection molding techniques. The light source 22 and light detector 24 are mounted on a Printed Circuit Board (PCB) or other substrate (302), and the lower portion 100 of the housing is attached (e.g., by adhesive) to the side of the PCB on which the devices 22, 24 are mounted (304). In some cases, as shown in FIG. 4, the separate assembly 200 for the reflective surface 28 is then aligned and secured in the light reflecting chamber 29 (306). Next, the second portion 102 of the housing 60 is attached (e.g., by adhesive) to the first portion 100 of the housing (308). As described above, the features 206, 208 (fig. 4) may facilitate alignment of the two housing portions 100, 102.

In some embodiments, the aforementioned manufacturing method may be performed as part of a wafer level process. Wafer level processes allow multiple modules to be manufactured simultaneously. In a wafer level process, a plurality of light sources and light detectors are mounted on a substrate (e.g., printed circuit board, PCB) wafer. After attaching the wafers forming the first and second portions of the housing, the stack may be singulated (e.g., by dicing) into individual modules, such as the modules described above.

The particulate matter sensor modules described herein can be incorporated into, for example, microfluidic particulate matter sensor systems. In some cases, the sensor system may include a microcontroller that controls the light source 22, a pump operable to drive a flow of fluid air through the sensor system, a pump controller operable to control the pump, and processing circuitry that processes signals from the light detector 24.

The fabrication of the particulate matter sensors and sensor systems described herein is compatible with high-throughput, low-cost manufacturing techniques, such as injection molding and microelectronic processing and packaging techniques, so that these sensors and sensor systems can be manufactured quickly and economically.

As shown in fig. 8, a particulate matter sensor system 450 including a particulate matter sensor module (e.g., module 20A or 20B) can be incorporated into a mobile or handheld computing device 452, such as a smartphone (as shown), tablet, or wearable computing device. The particulate matter sensor system 450 can be operated by a user (e.g., under control of an application running on the mobile computing device 452) to perform an air quality test. The test results may be displayed on a display 454 of the mobile computing device 452 to, for example, provide substantially immediate feedback to the user regarding the air quality in the user's environment.

The particulate matter sensor system described herein may also be incorporated into other devices, such as air purifiers or air conditioning units; or for other applications such as automotive or industrial applications.

Various modifications will be apparent, and modifications may be made to the foregoing examples. In some cases, features described in connection with different embodiments may be combined into the same embodiment, and various features described in connection with the foregoing examples may be omitted from some embodiments. Accordingly, other implementations are within the scope of the following claims.