Longitudinal resonating mode inertial mass sensing systems

摘要

The subject invention provides improved means to measure mass collected on a sample collection surface in real time. A resonant structure is used as the “scale” to determine the mass in real time. The invention employs a membrane, or collection substrate, on the end of a resonant structure resonating in the longitudinal direction. A structure resonating in the longitudinal mode offers a considerably higher resonant frequency than the same structure in the bending mode. The higher the resonant frequency, the more resolution in the frequency of oscillation is available to determine the mass of the collection surface or membrane. The present invention implements this attribute in connection with such a structure.

主权项

1. An inertial mass sensor, comprising:
a. a collection filter that collects particulate matter from a fluid; b. a generally cylindrically shaped resonator, coupled to the collection filter, and having a length, a diameter and a longitudinal axis, and tapered to have a varying modulus of elasticity along its longitudinal axis;
i. the resonator being configured for achieving reciprocating linear movement along its longitudinal axis located along the length of the cylinder;ii. having a first end and a second end; andiii. the collection filter being mounted to the first end of the resonator; c. a housing having an upper base and a lower base structure, surrounding the resonator, comprising:
i. a cavity having a diameter greater than the diameter of the resonator; d. a first magnet, coupled to and surrounding the first end of the resonator; e. a drive coil that:
i. surrounds the magnet; andii. generates an alternating electric current to produce reciprocating linear movement of the magnet/resonator along the longitudinal axis of the resonator wherein the reciprocating linear movement has a resonant frequency that varies depending on the mass of the particulate matter in the collection filter; f. a means for sensing the resonance frequency of the resonator, located at the second end of the resonator; and g. a means for measuring the mass or resonant frequency of the particulate matter.