Piezoelectric Crystal Microbalance Driving Circuit Study

Based on the quality of the adsorption effect of the piezoelectric resonant sensor type biosensor is a collection of electronic,mechanical,computer and molecular biology,and other multi-disciplinary development results in the integration of the new sensor technology,because of the Quartz Crystal resonator theory and processing technology mature,resonant frequency and stable chemical properties,sources,low price,since the Sauerbrey 1959 Quartz Crystal micro-balances(QCM),piezoelectric resonant sensor has been based on Quartz Crystal piezoelectric materials.QCM design is simple in principle,good stability,high sensitivity,simple measurement system,convenient operation,low cost,can be real-time online detection and digital output etc,has been widely studied for hazardous organic compounds detection,DNA testing,blood component detection,toxin detection,etc.In the real test,biological sensors often require work in liquid phase environment.Due to the viscoelastic properties of the liquid,when the piezoelectric resonator electrode in contact with the liquid to be tested,can lead to a significant decrease mechanical quality factor of resonator,how to maintain the stability of the resonant sensor system,in order to obtain sufficient signal-to-noise ratio to achieve accurate measurement,is an important topic of the resonant piezoelectric biosensor research.In recent years,the development of new type of piezoelectric materials quickly,the gallium lanthanum silicate(langasite)because have many is better than that of quartz Crystal and caught the attention of everyone,and studies have shown that under the environment of the liquid phase,the Q value of gallium lanthanum silicate Crystal is almost twice of quartz Crystal,obviously a langasite Crystal Microbalance(LCM)will have a better stability in liquid phase.This inspired our r&d a new piezoelectric crystal materials based on the monolithic array type piezoelectric resonant biosensors,so as to realize in this article,through the study of classic QCM design platform,analogy QCM design of drive circuit,developed a set of can be used for quartz and gallium lanthanum silicate crystals resonant devices using resonant sensor,the design of the working principle of the circuit based on phase-locked loop simulation can effectively compensated crystal static capacitance,eliminate the phase error,crystal can lock in the series resonance condition,through an external device can measure precision high crystal resonant frequency and dynamic resistance.The internal oscillation circuit implemented by chip MC12148 external varactor,access to a very wide frequency range to use crystal.Finally the article LCM usage made some exploration in the liquid phase,believed to be the material used for piezoelectric crystal micro scale preparation has the very good application prospect.