RESONANT FIBER BASED AEROSOL PARTICLE SENSOR AND METHOD

摘要

The present invention relates to methods and devices for determining the weight of small particles, typically being nano-sized particles by use of resonating fibers in the form of elongate members being driven into resonance by an actuator or e.g. thermal noise/fluctuation. The frequency shift in resonance frequency due to depositing of nano-sized particles is correlated with the mass deposited on the elongate member and the vibration frequency of the elongate member is determined by a detector. The read-out from the detector is transformed into a mass deposited on the elongate member. Particles are deposited by letting a fluid with the particles flow past the elongate member.

主权项

1. A method for determining the weight of aerosol particles, the method utilises a sensor system comprising a sensor element comprising a base member, one or more elongate members an actuator for driving the one or more elongate members into resonance, and a detector for determining the vibration frequency of the one or more elongate members, wherein
each of the one or more elongate members are made from an elastic material with a longitudinal extension, being at least ten times the diameter or the equivalent diameter of the cross section of the elongate member, the diameter or equivalent diameter being in range of 1 nm-100 μm, each of the one or more elongate members being attached at least at one end to the base member or at a nodal point of the vibrational displacement through a connection and extends in a straight manner out from the base member, so as not to extend along and above the surface of the base member,the method comprising the step of
producing a flow of aerosol past one or more of the elongate members in an oblique direction, such as perpendicular, to the longitudinal direction of the elongate member, wherein:
the velocity of the aerosol is higher than 1 m/s, and/orone or more of the elongate members being electrostatic charged vibrating and detecting vibration frequency of the elongate member by use of the actuator and detector, so as to determine the resonance frequency, and determining the weight of the aerosol particles from the detected resonance frequency.wherein
the sensor system comprises a region immediate downstream of the elongate member(s) devoid of obstacles, the extension of said region being at least 100-1,000 diameters or equivalent diameters of the elongate member(s).