Piezoelectric sensors have emerged as a versatile tool for measurement of various quantities such as pressure, acceleration, strain, or force across many industrial applications. When mechanically strained, electric charges are produced inside a piezoelectric transducer. These charges result in an electric field that may be measured as a voltage difference between two electrodes, from which the...

Variable acoustic properties can be obtained at the diaphragm of an electroacoustic transducer, with the help of very basic control strategies, among which is the simple electrical shunting of the transducer. These shunt techniques are compared to active feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. It is shown here that the formulation of feedback...

A novel assay for surface DNA hybridization, which is free of sample and probe labeling, convenient and of low cost, sensitive and capable of differentiation of single-base mutations, is reported. Hairpin oligonucleotides are carefully designed as probes and are covalently attached to Si chips. Segments of the human p53 gene are chosen to demonstrate the major features of the novel technique. I...

Electric fish evaluate the near environment by detecting changes in their self-generated electric organ discharge. To investigate impedance modulation of the self-generated electric field, this field was measured at the electrosensory fovea of Gymnotus carapo in the presence and absence of objects. Changes in local fields provoked by resistive objects were predicted by the change in total energ...

This paper presented an improved algorithm using digitally synthesized excitation signal sources for efficient and accurate measurement of the E/M impedance for structural health monitoring with PWAS (piezoelectric wafer active sensor) transducers. Instead of using a sinusoidal excitation to measure the structural E/M impedance at a single frequency at a time, the digitally synthesized signal s...

BACKGROUND For electroporation-based therapies, accurate modeling of the electric field distribution within the target tissue is important for predicting the treatment volume. In response to conventional, unipolar pulses, the electrical impedance of a tissue varies as a function of the local electric field, leading to a redistribution of the field. These dynamic impedance changes, which depend ...

In this study, new impedance measurement techniques are developed specially for structural health monitoring of large-scale structures. Electromechanical (EM) impedance based damage detection techniques, which utilize the electromechanical coupling effect between a piezoelectric transducer such as lead zirconate titanate (PZT) and a host structure, have been shown to be very sensitive to local ...