Sensors, electroacoustic

Based on a thin-fllm bulk acoustic wave resonators (TFBAR) coated with tetraphenyl CoPP, an electroacoustic chemical sensor can detect ethanol vapor down... 

Assnming small pertnrbations to be directly additive, the mechanical and electrical pertnrbation can be treated independently. In most of the SAW sensors, a metalized condncting layer is employed, resulting in negligible electroacoustic effect. Under these conditions, the third and fourth terms in Equation 4.4 are omitted and the... 

The DT-1200 has two separate sensors for measuring acoustic and electroacoustic signals separately. Both sensors use the pulse technique. The acoustic sensor has two piezo crystal transducers. The gap between the transmitter and receiver is variable in steps. In default mode, the gap changes from 0.15 mm up to 20 mm in 21 steps. The basic frequency of the pulse changes in steps as well. In default mode, the frequency changes from 3 to 100 MHz in 18 steps. The number of pulses collected for each gap and frequency is automatically adjustable in order to reach the target signal-to-noise ratio. 

The electroacoustic sensor measures the magnitude and phase of the CVC at 1.5 and 3 MHz. It has a piezo crystal sound transmitter and a specially designed electric antenna. The distance between the transmitter and antenna is 5 mm. There is a provision for automatic correction of the sound speed and attenuation measured with the acoustic sensor. 

Figures 8 and 9 illustrate the precision of the electroacoustic sensor. Figiue 8 provides results for 51 continuous CVC measurements on silica Ludox. The precision meas-lued as the absolute variation of the zeta potential measurement is a fraction of a millivolt. Figure 9 shows titration...

Piezoelectric devices are used in the following areas Measurement of pressure, measurement of vibrations, stress gauge, strain gauge, measurement of acceleration, impact detector, position sensors. There is a wide choice of materials and material forms that are actively piezoelectric. Most of them have the ability to convert mechanical strain into an electrical charge when used as sensor, and to do the opposite when used as an actuator. Studies of piezoelectric semiconductors, nonlinear effects and surface waves led to constraction of useful devices. The research of sophisticated electroacoustic devices may one day simplify the dialogue between the user and the computer. There are matty more examples of this kind one coirld mention. 

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