Improved frequency/voltage converters for fast quartz crystal microbalance applications
- GIBEC-Escuela de Ingenieria de Antioquia, Universidad CES, Calle 25, Sur No. 42-73, Envigado (Colombia)
- Departamento Ingenieria Electronica. ETSI de Telecomunicacion, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia 46022 (Spain)
- Universite Pierre et Marie Curie-Paris 6, Laboratoire Interfaces et Systemes Electrochemiques, CNRS, UPR15-LISE, 4 place Jussieu, Paris 75252 (France)
The monitoring of frequency changes in fast quartz crystal microbalance (QCM) applications is a real challenge in today's instrumentation. In these applications, such as ac electrogravimetry, small frequency shifts, in the order of tens of hertz, around the resonance of the sensor can occur up to a frequency modulation of 1 kHz. These frequency changes have to be monitored very accurately both in magnitude and phase. Phase-locked loop techniques can be used for obtaining a high performance frequency/voltage converter which can provide reliable measurements. Sensitivity higher than 10 mV/Hz, for a frequency shift resolution of 0.1 Hz, with very low distortion in tracking both the magnitude and phase of the frequency variations around the resonance frequency of the sensor are required specifications. Moreover, the resonance frequency can vary in a broad frequency range from 5 to 10 MHz in typical QCM sensors, which introduces an additional difficulty. A new frequency-voltage conversion system based on a double tuning analog-digital phase-locked loop is proposed. The reported electronic characterization and experimental results obtained with conducting polymers prove its reliability for ac-electrogravimetry measurements and, in general, for fast QCM applications.
- OSTI ID:
- 21123896
- Journal Information:
- Review of Scientific Instruments, Vol. 79, Issue 4; Other Information: DOI: 10.1063/1.2908430; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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