Showing papers on "Piezoelectric sensor published in 1982"

Epidermis of human skin: pyroelectric and piezoelectric sensor layer

Abstract: The epidermis of live human skin has a permanent electric dipole moment perpendicular to its surface. Voltage responses to a rapid change of temperature are pyroeletric, while voltage responses to pressure pulses are piezoelectric in nature. The time course of the responses depends on dX/dt (X, temperature or pressure). The epidermal surface can react to all physical environmental influences to which nonbiological pyroelectric materials are known to respond. Epidermal voltage signals can be perceived through the intraepidermal and the superficial dermal nervous network. The pyroelectric and piezoelectric properties are also measurable on dead, dry skin samples.

Piezoelectricity of Uniaxially Oriented Polyvinylidene Fluoride

Abstract: Piezoelectric polyvinylidene fluoride (PVDF) shows promise as a material for ultrasonic a pplications. The development of piezoelectric transducers requires the knowledge of their dielectric, elastic and piezoelectric properties. I nvestigations of the material parameters are usually carried out by exciting piezoelectric resonances.However, piezoelectric resonances of PVDF films, showing high mechanical and dielectric losses,cannot be evaluated by standard methods. The material parameters were determined by means of network analysis. Additionally, quasistatic measurements of the elastic and piezoelectric p roperties were carried out. The observed frequency dependence of the elastic and piezoelectric constants is discussed. Using an interferometric method the Poisson ratios p3,and ~3~ are measured. These data are used to determine a complete set of elastic constants with the exception of the shear coefficients. The quasistatically measured elastic and piezoelectric data enabled us to calculate the i mportant piezoelectric constantse3,ande,,that could not be measured directly. The experimental results are compared with t heoretical models.

Vortex flow metering apparatus

Abstract: A vortex flow metering apparatus comprising a sensor unit having first and second piezoelectric sensors selectively arranged in the concavity or a vortex generator having a measured fluid produce a Karman's vortex according to its velocity, a first conversion amplifier to which a signal from the first piezoelectric sensor is applied, a second conversion amplifier to which a signal from the second piezoelectric sensor is applied, an operator circuit to which outputs from the first and second conversion amplifiers are applied and which through addition or subtraction and other operations, removes noise components due to disturbance vibrations. The first and second piezoelectric sensors are selectively arranged at two points whereat stress distribution of the noise component due to disturbance vibration and stress distribution of a signal component due to vortex dynamic lift are different from each other. The invention thus has an unexpectedly high signal to noise ratio, and extraneous noise due to a variety of disturbance vibrations, is substantially eliminated.

Piezoelectric pressure sensor

Abstract: A pressure sensor comprising a piezoelectric material formed in a geometry which provides a piezoelectric output signal when subjected to a pressure. The piezoelectric material also has a pyroelectric output signal. The present sensor further comprises conductive contacts having a geometry for enhancing the piezoelectric output signal and for substantially eliminating the pyroelectric output signal.

Transducer with a piezoelectric sensor element

Abstract: In addition to having at least one piezoelectric sensor element, a transducer is provided with at least one further measuring element, which is influenced by the state variable to be measured in the same way as the piezoelectric sensor element, and has its own signal lead. The additional measuring element may also be a piezoelectric element which may be excited so as to produce mechanical vibrations by utilizing the inverse piezo-effect, the change of the vibration characteristics of the vibration system consisting of the excited piezo-element and its environment serving as a measurement value for a static or quasi-static measurement.

Transducer with a piezo-electric sensitive element

Abstract: A piezoelectric transducer has, in addition to at least one piezoelectric sensor element has at least one further measuring element for static or quasi-static measurements which, in the same manner as the piezoelectric element is influenced by the quantity to be measured and has its own signal line. The additional sensing element may be formed of a piezoelectric element as well, which can be excited by making use of the inverse piezo effect to mechanical vibrations, the change in the oscillation behavior of the oscillation system formed by the excited piezo element and its environment serving as a measurement value for a static or quasi-static measurement.

Bimorph piezoelectric element

Abstract: PURPOSE:To obtain high elastic strength and universality in a bimorph piezoelectric element by aligning the polarizing direction of a plurality of piezoelectric plates in the same direction, andbonding thereto a single piezoelectric plate formed by laminating and bonding as one plate. CONSTITUTION:Two piezoelectric plates 1a which have a thickness of t0/2 are aligned as a piezoelectric plate corresponding to a single piezoelectric plate 1 having a thickness of t0 so that the polarizing directions are coincident, laminated and bonded with an adhesive having large elastic deformation state. The single piezoelectric plate 1' which is thus bonded is used and bonded to each of both sides of a metal plate 3, and electrodes 2 are attached to both side surfaces of a piezoelectric element 6'. In this manner, a bimorph piezoelectric element which has high elastic strength and excellent universality can be obtained.

Principle of piezoelectric frequency-tunable transducer

Abstract: Eecently, in our papers[1,2] the effect of electric load on the characteristics of piezoelectric vibration system has been obtained. The resonant frequency of such a system changes continually with the changing of the electric load. In accordance with this effect, we made piezoelectric frequency-tunable transducers. In this paper, the principle of this freqency-tunable piezoelectric transducer is described. We theoretically analyse the piezoelectric frequency-tuning of the sandwich transducers and experimentally investigate a sandwich transducer of length-vibration bar with field parallel to length. The theoretical and experimental results show that such frequency-tuning is available at one and half octaves. For piezoelectric frequency-tunable transducer, the frequency tuning is convenient, continual and instantaneous.