TY - GEN
T1 - Performance of micromachined quartz gravimetric sensors upon electrochemical adsorption of monolayers
AU - Kao, Ping
AU - Patwardhan, Ashish
AU - Allara, David
AU - Tadigadapa, Srinivas
AU - Strutwolf, Jörg
AU - Arrigan, Damien
PY - 2008
Y1 - 2008
N2 - This paper presents the results of electrochemical calibration experiments performed on micromachined quartz gravimetric sensors. The absolute mass sensitivity of bulk acoustic quartz crystal microbalance (QCM) can be improved into the sub-10-12 g range upon miniaturization of the resonator thickness and area. Using plasma etching, we have fabricated miniaturized QCMs with thicknesses of ∼29 μ̂m and diameters of 500 μ̂m with f0=58 MHz. Resonators with 60 nm thick Ti/Pt top electrodes were used to study the electrochemically induced oxide layer formation on the metal surface, the adsorption of hydrogen, and underpotential deposition (UPD) of Cu on Pt electrodes. The performance of microQCM is compared with the performance of a frequency matched overtone mode of a commercial 5 MHz resonator. Micromachined QCMs showed expected sensitivity improvement to UPD of Cu, however an unexpected hundred fold enhancement to oxygen and ∼28 times enhancement in the sensitivity to hydrogen adsorption was observed which may be due to the roughness/porosity of the electrodes.
AB - This paper presents the results of electrochemical calibration experiments performed on micromachined quartz gravimetric sensors. The absolute mass sensitivity of bulk acoustic quartz crystal microbalance (QCM) can be improved into the sub-10-12 g range upon miniaturization of the resonator thickness and area. Using plasma etching, we have fabricated miniaturized QCMs with thicknesses of ∼29 μ̂m and diameters of 500 μ̂m with f0=58 MHz. Resonators with 60 nm thick Ti/Pt top electrodes were used to study the electrochemically induced oxide layer formation on the metal surface, the adsorption of hydrogen, and underpotential deposition (UPD) of Cu on Pt electrodes. The performance of microQCM is compared with the performance of a frequency matched overtone mode of a commercial 5 MHz resonator. Micromachined QCMs showed expected sensitivity improvement to UPD of Cu, however an unexpected hundred fold enhancement to oxygen and ∼28 times enhancement in the sensitivity to hydrogen adsorption was observed which may be due to the roughness/porosity of the electrodes.
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U2 - 10.1109/ICSENS.2008.4716742
DO - 10.1109/ICSENS.2008.4716742
M3 - Conference contribution
AN - SCOPUS:67649946503
SN - 9781424425808
T3 - Proceedings of IEEE Sensors
SP - 1544
EP - 1547
BT - 2008 IEEE Sensors, SENSORS 2008
T2 - 2008 IEEE Sensors, SENSORS 2008
Y2 - 26 October 2008 through 29 October 2008
ER -