METHOD AND SENSOR FOR DETECTING AEROSOL PARTICLES IN AMBIENT AIR

Abstract

In a first aspect, the invention relates to a method for detecting aerosol particles in ambient air by means of a photoacoustic gas sensor, wherein an analysis volume is present in the beam path of a modulable emitter such that the emitter can use modulable radiation to excite aerosol particles in the analysis volume to form sound pressure waves which are detectable by means of the sensor. Using the modulable emitter, the analysis volume is irradiated with the modulated radiation to generate sound pressure waves. The generated sound pressure waves are measured by means of the sensor, whereby the presence and/or concentration of the aerosol particles in the ambient air is determined on the basis of the measurement results. Particularly preferably, the aerosol particles are bioaerosols, preferably pollen, spores, bacteria and viruses. In a further aspect, the invention preferably relates to a photoacoustic gas sensor suitable for carrying out the method.

Claims

1. A method for the detection of aerosol particles in ambient air, comprising a. providing a photoacoustic gas sensor comprising. a modulable emitter, an analysis volume which is in fluid communication with the ambient air, wherein the analysis volume is an open system having one or more openings such that ambient air comprising aerosol particles can flow or diffuse into the analysis volume, a MEMS sensor for the detection of sound pressure waves, wherein the analysis volume is present in the beam path of the emitter such that the emitter can use modulable radiation to excite aerosol particles in the analysis volume to form sound pressure waves which are detectable by means of the sensor, b. irradiating the analysis volume with radiation modulated with a modulation frequency to generate sound pressure waves c. measuring the generated sound pressure waves by means of the sensor d. determining the presence and/or concentration of aerosol particles in the ambient air based on the measurement results, wherein the aerosol particles are bioaerosols and wherein the selective excitation and detection of the aerosol particles is performed by tuning the wavelength of the emitted radiation to the absorption behavior of the aerosol particles.

2. (canceled)

3. The method according to claim 1, wherein the aerosol particles are pollen, spores, bacteria or viruses.

4. The method according to claim 1, wherein the aerosol particles are bioaerosols, preferably pollen, spores, bacteria or viruses, wherein the one or more wavelengths of the emitter for selective excitation are preferably selected from a range between 170 nm and 1000 nm.

5. The method according to claim 1, wherein the modulable emitter permits wavelength-selective radiation and/or a wavelength-selective filter, for example a Fabry-Perot filter, is present in the beam path between the emitter and the analysis volume.

6. The method according to claim 1, wherein the modulable emitter is an infrared emitter or a UV emitter.

7. (canceled)

8. The method according to claim 1, wherein the MEMS sensor is a sound pressure detector.

9. A photoacoustic gas sensor for detecting aerosol particles in ambient air by a method according to claim 1, comprising a modulable emitter, an analysis volume which is in fluid communication with the ambient air,. wherein the analysis volume is an open system having one or more openings such that ambient air comprising aerosol particles can flow or diffuse into the analysis volume, a MEMS sensor for the detection of sound pressure waves, wherein the detection chamber is present in the beam path of the emitter such that the emitter can use modulable radiation to excite aerosol particles in the analysis volume to form sound pressure waves which are detectable by means of the sensor, wherein the aerosol particles are bioaerosols and wherein the photoacoustic gas sensor comprises a control unit configured to control the emitter to selectively excite and detect the aerosol particles, wherein the wavelength of the emitted radiation is tuned to the absorption behavior of the aerosol particles to be detected.

10. (canceled)

11. The photoacoustic gas sensor according to claim 9, wherein the photoacoustic gas sensor comprises a data processing unit configured to make a determination about the presence and/or concentration of the aerosol particles in the ambient air based on an evaluation of measurement results for the generated sound pressure waves.

12. The photoacoustic gas sensor according to claim 9, wherein the photoacoustic gas sensor comprises a signal generator, the data processing means being configured to generate a warning signal by means of the signal generator if the detected concentration of the aerosol particles in the ambient air exceeds a predetermined threshold.

13. The method according to claim 8, wherein the sound pressure detector comprises a capacitively or optically readable piezoelectric, piezoresistive and/or magnetic beam and/or a capacitive, piezoelectric, piezoresistive and/or optical microphone

Description

DETAILED DESCRIPTION

[0161] In the following, the invention will be explained in more detail by means of examples and figures, without being limited to them.

[0162] FIG. 1 is a schematic illustration of a preferred embodiment of the method for the detection of aerosol particles in ambient air, using the example of a virus.

[0163] Electromagnetic radiation is generated by means of a modulable emitter, in particular in the infrared, visible or ultraviolet wavelength range. The emitter is preferably arranged and configured so that the radiation emitted by the emitter is substantially incident on the analysis volume. If the modulated irradiation occurs at a wavelength corresponding to the absorption spectrum of a virus located in the analysis volume, modulated absorption takes place, resulting in heating and cooling processes whose time scales reflect the modulation frequency of the radiation. In particular, the protein envelope of viruses can absorb the electromagnetic radiation and lead to expansion.

[0164] According to the photoacoustic effect, the heating and cooling processes lead to expansions and contractions of components of the virus (in particular the proteins of the protein envelope) or of the entire virus, resulting in the formation of sound pressure waves with essentially the modulation frequency. The sound pressure waves can be measured by a sound detector, e.g. a microphone. The power of the sound waves is preferably directly proportional to the concentration of the viruses in the analysis volume.

[0165] FIG. 2 illustrates the different sizes and types of aerosol particles that can advantageously be detected with the method according to the invention.

LITERATURE

[0166] Tobias, H. Bioaerosol mass spectrometry for rapid detection of individual airborne Mycobacterium tuberculosis H37Ra particles. Appl. Environ. Microbiol. 71, 6086-6095 (2005). [0167] Fernstrom A. et al, Aerobiology and Its Role in the Transmission of Infectious Diseases Journal of Pathogens Volume 2013, Article ID 493960, 13 pages. [0168] Senguptaa, A., Brarb, N. & Davis, E. J. Bioaerosol detection and characterization by surface-enhanced Raman spectroscopy. J. Colloid Interface Sci. 309, 36-43 (2007). [0169] Schafer, M. P. et al. 1999. detection and characterization of airborne Mycobacterium tuberculosis H37Ra particles, a surrogate for airborne pathogenic M. tuberculosis. Aerosol Sci. Technol. 30:161-173. [0170] Park, Kyu-Tae et al. Detection of airborne viruses using electro-aerodynamic deposition and a field-effect transistor, Scientific Reports |5:17462| DOI: 10.1038/srep17462. [0171] Huffman et al Real-time sensing of bioaerosols: Review and current perspectives AEROSOL SCIENCE AND TECHNOLOGY 2020, VOL. 54, NO. 5, 465-495. [0172] MARSH, D. G. (1975). Allergens and the genetics of allergy; in M. Sela (ed), The Antigens, Vol. 3, pp 271-359. (Academic Press Inc., London, New York).