Characterizing the Spatially Dependent Sensitivity of Resonant Mass Sensors Using Inkjet Deposition

Abstract

Micro- and millimeter-scale resonant mass sensors have received widespread attention due to their robust and sensitive performance in a wide range of detection applications. A key performance metric for such systems is the sensitivity of the resonant frequency of a device to changes in mass, which needs to be calibrated. This calibration is complicated by the fact that the position of the added mass on a sensor can have an effect on the measured sensitivity—therefore, a spatial sensitivity mapping is needed. To date, most approaches for experimental sensitivity characterization are based upon the controlled addition of small masses, e.g., the direct attachment of microbeads via atomic force microscopy or the selective microelectrodeposition of material, both of which are time consuming and require specialized equipment. This work proposes a method of experimental spatial sensitivity measurement that uses an inkjet system and standard sensor readout methodology to map the spatially dependent sensitivity of a resonant mass sensor—a significantly easier experimental approach. The methodology is described and demonstrated on a quartz resonator. In the specific case of a Kyocera CX3225 thickness-shear mode resonator, the location of the region of maximum mass sensitivity is experimentally identified.

Sorption Kinetics of Poly(ethyleneimine)–Poly(ethylene Oxide) Blends and the Implication for Low-Cost, Small-Scale CO2 Sensors

“…As CO 2 adsorbs on the resonator (increasing the total mass), the oscillation frequency of the resonator decreases, allowing real-time monitoring of the sorption kinetics. The observed frequency shift is correlated to the deposited mass by 54,55…”

“…As CO 2 adsorbs on the resonator (increasing the total mass), the oscillation frequency of the resonator decreases, allowing real-time monitoring of the sorption kinetics. The observed frequency shift is correlated to the deposited mass by , where Δ m is the change in mass, S m is the mass sensitivity of the sensor, f 0 is the resonance frequency of the unloaded resonator, and Δ f is the change in the resonance frequency. Thus, an increase in the mass of CO 2 adsorbed would result in a proportional decrease in the resonance frequency.…”