Abstract: A sensor, method and system, for measuring certain characteristics of a fluid. The sensor utilizes a piezoelectric device having at least two tightly coupled resonators providing a two pole electric transfer function responsive to an electrical signal coupled to the input resonator. The piezoelectric sensor has a textured entrapment layer, constructed to entrap a known volume of fluid and impart motion to the entrapped fluid as well as to surrounding non-trapped fluid. The common mode frequency shift of the two resonant frequencies is related to mass loading due to the entrapped fluid, while the energy absorbed by the fluid, or a phase shift of one of the resonant frequencies, is related to the viscosity/density product of the fluid. Extracting the viscosity is a matter of mathematical manipulation. By controlling the energy level of the input electrical signal, the viscosity measurement may be conducted at a predetermined shear rate.

Abstract: An apparatus and a method for controlling the shear rate at which an acoustic wave device measures viscosity, by utilizing an automatic level control or an automatic gain control circuit to control power input to the sensor as a function of the sensor's output power. Further improvement is provided by measuring the input power and combining the input power and output power measurements, preferably by averaging, to control the input power to the sensor. A method is also provided for characterizing the fluid under test by providing a set of viscosity measurements at various shear rates.

Abstract: A method for controlling the shear rate at which an acoustic wave device measures viscosity by calculating the shear rate as a function of the characteristic rate of quartz movement in response to a given input transducer power level and the viscosity of the fluid and then by adjusting the input transducer power level to obtain the desired shear rate for the viscosity measurement by optimizing the power level. Related aspects of the invention provide for methods for characterizing viscoelastic fluids at a plurality of predetermined shear rates using a plurality of optimized power levels, a plurality of sensor designs, or a plurality of both optimized power levels and sensor designs.

Abstract: A method for measuring viscosity and shear rate at which the measurement is performed is provided, by utilizing an acoustic wave sensor, and calculating the shear rate as a function of the characteristic rate of quartz movement in response to a given power transmitted to a fluid, and the viscosity of the fluid. Related aspects of the invention provide for methods for controlling the shear rate at which a viscosity measurement is performed, and characterizing viscoelastic fluids at a plurality of shear rates.

Abstract: A diode detector comprising a detector network adapted to detect and multiply the detected voltage coupled to a divider network that comprise diodes in equal number to the number of diodes in the detector network, provides a passive detector applicable to any application requiring a small, efficient, high output, inexpensive temperature compensated detector for use as demodulator or as power to voltage converter. Integrating a portion of the divider network in the detector/multiplier network allows control over the minimum input impedance of the detector.

Abstract: An acoustic wave device, which utilizes multiple localized reflections of acoustic wave for achieving an infinite impulse response while maintaining high tolerance for dampening effects, is disclosed. The device utilized a plurality of electromechanically significant electrodes disposed on most of the active surface. A plurality of sensors utilizing the disclosed acoustic wave mode device are also described.