We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated.
References
[1]
Sun, Z.; Huang, Z.; Wang, J.S. Studies on the size distribution, number and mass emission factors of candle particles characterized by modes of burning. J. Aerosol Sci？2006, 37, 1484–1496, doi:10.1016/j.jaerosci.2006.05.001.
Davitt, K.M.; Song, Y.K.; Patterson, W.R., III; Nurmikko, A.V.; Pan, Y.L.; Chang, R.K.; Gherasimova, M.; Han, J.; Cobler, P.J.; Butler, P.D.; Palermo, V.; Gaska, R. A compact aerosol sensor and spectroscopic sorting with UV LEDs. Proceedings of the Optically Based Biological and Chemical Detection for Defense III, Stockholm, Sweden, September 11–13, 2006; pp. 63980B1–63980B9.
[4]
Ouazzani, K.; Bentama, J. A promising optical technique to measure cake thickness of biological particles during a filtration process. Desalination？2007, 206, 36–41, doi:10.1016/j.desal.2006.01.038.
[5]
Zemlyanov, A.A.; Geints, Y.E. Aerosol scattering of supercontinuum radiation formed upon femtosecond laser pulse filamentation in the atmosphere. Opt. Commun？2007, 270, 47–50, doi:10.1016/j.optcom.2006.08.028.
[6]
Satake, D.; Ebi, H.; Oku, N.; Matsuda, K.; Takao, H.; Ashiki, M.; Ishida, M. A sensor for blood cell counter using MEMS technology. Sens. Actuators B？2002, 83, 77–81, doi:10.1016/S0925-4005(01)01045-0.
[7]
Tanabe, R.; Hata, S.; Shimokohbe, A. MEMS complete blood count sensors designed to reduce noise from electrolysis gas. Microelectron. Eng？2006, 83, 1646–1650, doi:10.1016/j.mee.2006.01.233.
Lim, H.H.; Park, D.; Maeng, J.Y.; Hwang, J.; Kim, Y.J. MEMS based integrated particle detection chip for real time environmental monitoring. Proceedings of the 18th IEEE International Conference on Micro Electro Mechanical Systems (MEMS), Istanbul, Turkey, January 22–26, 2006; pp. 62–65.
[10]
Maeng, J.Y.; Park, D.; Kim, Y.H.; Hwang, J.; Kim, Y.J. Micromachined cascade virtual impactor for aerodynamic size classification of airborne particles. Proceedings of the 19th IEEE International Conference on Micro Electro Mechanical Systems (MEMS), Kobe, Japan, January 21–25, 2007; pp. 62–65.
[11]
Tzou, T.Z. Aerodynamic particle size of metered-dose inhalers determined by the quartz crystal microbalance and the Andersen cascade impactor. Int. J. Pharm？1999, 186, 71–79, doi:10.1016/S0378-5173(99)00139-8. 10469925
[12]
Nakamoto, T.; Suzuki, Y.; Moriizumi, T. Study of VHF-band QCM gas sensor. Sen. Actuators B？2002, 84, 98–105, doi:10.1016/S0925-4005(01)01066-8.
[13]
Timbrell, S.T. Human exposure to asbestos: dust controls and standards. The inhalation of fibrous dusts. Ann. N. Y. Acad. Sci？1965, 132, 255–273, doi:10.1111/j.1749-6632.1965.tb41107.x. 5219552
[14]
Hounam, R.F.; Sherwood, R.J. The cascade centripeter: a device for determining the concentration performance. Am. Ind. Hyg. Assoc. J？1965, 26, 122–131, doi:10.1080/00028896509342711. 5828113
[15]
Lim, K.S; Lee, K.W. Collection efficiency and particle loss of virtual impactors with different methods of increasing pressure drop. J. Aerosol Sci？2006, 37, 1188–1197, doi:10.1016/j.jaerosci.2005.11.011.
