Showing papers on "Interdigital transducer published in 1992"
TL;DR: In this article, an acoustic plate mode (APM) in a piezoelectric crystal plate as the sensing element has been designed, fabricated and tested for DNA hybridization.
Abstract: A prototype biosensor, which utilizes an acoustic plate mode (APM) in a piezoelectric crystal plate as the sensing element, has been designed, fabricated and tested. The APM is selectively excited and received by aluminum interdigital transducers (IDTs), which are fabricated on a Z-cut X-propagating lithium niobate (ZX-LiNbO3) substrate using standard photolithographic techniques. The biological film is bound to the face of the ZX-LiNbO3 plate opposite to the IDTs. Appropriate r.f. electronics are used with the APM device to form the complete biosensor. Tests relating to the detection of deoxyribonucleic acid (DNA) hybridization demonstrate that the biosensor exhibits a high level of sensitivity, selectivity and reproducibility.
63 citations
TL;DR: In this article, an acoustic plate mode (APM) device on Z-cut, X-propagating LiNbO3, a high piezoelectric coupling material, is investigated as detectors in dilute electrolyte or metal-ion solutions.
Abstract: Acoustic plate mode (APM) devices on Z-cut, X-propagating LiNbO3, a high piezoelectric coupling material, are investigated as detectors in dilute electrolyte or metal-ion solutions. The sensing wave is an APM, a slow shear wave coupled to the interdigital transducer, which results in a relatively strong acoustic-ionic interaction. The resulting electrical loading leads to a measurable perturbation in the wave-propagation characteristics, which can then be related to the liquid electrical properties. Experiments conducted at different frequencies with various solutions that compare well with theoretical results show a detector that is at least two orders of magnitude more sensitive than similar APM sensors on quartz. These promising results have also led to the investigation of the detection of aqueous transition-metal ions (Fe3+, Cu2+, etc.) using solution conductivity changes rather than the commonly used mass sensitivity. The method involves the bonding of metal ions in soluiton to a ligand-coated silica or LiNbO3 support, placed adjacent to the APM device and in the path of the liquid flow. The resulting frequency increase is then interpreted in terms of the concentration of the metal ions. X-ray photoelectron spectroscopy analysis of the coated surface is performed to confirm the binding.
46 citations
TL;DR: In this article, a single-stage low-sidelobe weighted-coupled integrated acoustooptic tunable filter (IAOTF) operating at the optical wavelength of 131 mu m has been realized on a Y-cut X-propagating LiNbO/sub 3/ substrate for the first time.
Abstract: A single-stage low-sidelobe weighted-coupled integrated acoustooptic tunable filter (IAOTF) operating at the optical wavelength of 131 mu m has been realized on a Y-cut X-propagating LiNbO/sub 3/ substrate for the first time The weighted-coupling, which enabled the achievement of low-sidelobe levels, was facilitated by focused surface acoustic waves generated by a curved interdigital transducer First sidelobe levels as low as -176 dB have been obtained Optical bandwidth of 4 nm and tuning range of 170 nm for an interaction length of 6 mm were also accomplished >
40 citations
TL;DR: In this article, an electron cyclotron resonance (ECR) sputtering system was used to drive a Rayleigh SAW of 700 MHz without heating the substrate (room temperature), while it was impossible to drive such a wave conventionally, using other sputtering systems.
Abstract: Piezoelectric properties of ZnO films were investigated for the first time by means of an electron cyclotron resonance (ECR) sputtering system. It is confirmed that this system is capable of depositing a ZnO film with a large specific resistance, a good piezoelectric property and good c-axis orientation on an interdigital transducer (IDT)/glass substrate at a low temperature (less than 200°C) and under low gas pressure (~10-4 Torr). These ZnO films exhibited excellent surface acoustic wave (SAW) characteristics (insertion losses) and effective electromechanical coupling factors (keff) compared with ZnO films deposited by a conventional RF magnetron sputtering system. Furthermore this ECR sputtering system was capable of depositing a ZnO film capable of driving a Rayleigh SAW of 700 MHz, without heating the substrate (room temperature), while it was impossible to drive such a wave conventionally, using other sputtering systems.
23 citations
TL;DR: In this article, the authors measured liquid viscosity using shear horizontal (SH) wave propagation characteristics on a piezoelectric ceramic thin plate and found a linear relationship between the fractional phase velocity change of the S0 mode and the square root of the liquid viscoverage.
Abstract: Liquid viscosity measurement using shear horizontal (SH) wave propagation characteristics on a piezoelectric ceramic thin plate is described. The mode conversion loss associated with the compressional component U3 is zero, because the SH wave on the piezoelectric ceramic substrate poled along the horizontal axis has only the horizontal component U2, The IDT has a much larger electromechanical coupling factor for the S0 mode SH wave than that of the SH surface acoustic wave (SAW). The metal-coated condition of the liquid-loaded surface is essential for detecting the liquid viscosity. There exists a linear relationship between the fractional phase velocity change of the S0 mode and the square root of the liquid viscosity. The measured results on liquid viscosity using the S0 mode SH wave devices, for some concentrations of glycerol-water solutions, are in good agreement with the theoretical prediction.
17 citations
01 Jan 1992
TL;DR: In this article, the authors used surface acoustic wave (SAW) devices for the detection of both physical and chemical quantities, where the SAWs in the field of sensors give rise to an interesting basic detecting technique since the mechanism of interaction between the acoustic propagation, which induces the sensor response, includes many different linear and non linear properties of the propagation medium related to mass density, elastic stiffness and, in piezoelectric materials, also to the electric and dielectric behaviour.
Abstract: In recent years there has been a great interest in using surface acoustic wave (SAW) devices for the detection of both physical and chemical quantities. The SAWs in the field of sensors give rise to an interesting basic detecting technique since the mechanism of interaction between the acoustic propagation, which induces the sensor response, includes many different linear and non linear properties of the propagation medium related to mass density, elastic stiffness and, in piezoelectric materials, also to the electric and dielectric behaviour. In addition, as the acoustic energy is confined to a thin near-surface region of the substrate, SAWs are highly sensitive to surface perturbations of the propagation medium.
16 citations
Patent•
02 Mar 1992TL;DR: In this paper, a shear transverse wave device (10) having transitions in the relaxation or tightening of wave trapping has been presented, where wave trapping fingers are disposed within a propagation region between a transmitting and a receiving interdigital transducer (16 and 26).
Abstract: A shear transverse wave device (10) having transitions in the relaxation or tightening of wave trapping Two embodiments are preferably utilized simultaneously A first embodiment involves wave trapping fingers (38, 40, 42, 44 and 46) disposed within a propagation region between a transmitting and a receiving interdigital transducer (16 and 26) The wave trapping fingers provide a high width-to-spacing ratio of fingers proximate to the transducers and provide a lower ratio with approach to a center of the propagation region The relaxed trapping reduces the adverse effects caused by surface perturbations, while the tight trapping at the transducers provides an efficient coupling of power to and from the device The second embodiment is likewise concerned with decoupling of power Absorptive film (56 and 66) is placed at the opposed edges of the device to suppress spurious reflections from the edges (52 and 54) A grating (48 and 50) of fingers between each transducer and the associated edge is designed to provide a tightening of trapping with departure from the transducers, thereby allowing a more efficient absorption by the absorptive film, which is deposited on the fingers (60 and 64) closest to the opposed edges Again, the width-to-spacing ratio is varied to achieve the increase in wave trapping
16 citations
20 Oct 1992
TL;DR: In this article, an 878-MHz IIDT-type surface acoustic wave (SAW) filter with suppressed sidelobes and reduced insertion losses is described. But the insertion losses are less than 3 dB.
Abstract: Interdigitated interdigital transducer (IIDT)-type surface acoustic wave (SAW) filters with suppressed sidelobes and reduced insertion losses are described. The filters are composed of multiple withdrawal-weighted IDTs in different withdrawal positions. An 878-MHz filter composed of 13 IDTs was designed by this method. This filter has a minimum insertion loss of 1.6 dB and a stopband rejection of about 30 dB. Three filters with center frequencies of 0.9 GHz, 1.5 GHz, and 1.9 GHz were fabricated using the lift-off process. Their frequency responses are almost the same, and the insertion losses are less than 3 dB. >
15 citations
Patent•
26 Mar 1992
TL;DR: A surface acoustic wave element has first and second interdigital electrodes each having a thickness on a piezoelectric or electrostrictive substrate as discussed by the authors, and positive and negative electrodes are alternately arranged such that their electrode widths and periods are gradually increased or decreased in the direction of propagation of the acoustic wave.
Abstract: A surface acoustic wave element has a low insertion loss in one direction and a wide band width. This surface acoustic wave element has first and second interdigital electrodes each having a thickness on a piezoelectric or electrostrictive substrate. In a first interdigital electrode for exciting a surface acoustic wave, positive and negative electrodes are alternately arranged such that their electrode widths and periods are gradually decreased in a direction of propagation of the surface acoustic wave. In a second interdigital electrode for receiving the surface acoustic wave, positive and negative electrodes are alternately arranged such that their electrode widths and periods are gradually increased or decreased in the direction of propagation of the surface acoustic wave.
13 citations
Patent•
18 Dec 1992
TL;DR: A surface acoustic wave convolver includes first and second interdigital electrodes for exciting surface acoustic waves and an output electrode for detecting the surface acoustic signals to extract a convolution output as an electrical signal as discussed by the authors.
Abstract: A surface acoustic wave convolver includes first and second interdigital electrodes for exciting surface acoustic waves and an output electrode for detecting the surface acoustic waves to extract a convolution output as an electrical signal, the first and second interdigital electrodes and the output electrode being formed on a piezoelectric or electrostrictive substrate. In order to improve convolution efficiency and obtain wide-range characteristics, each of the first and second interdigital electrodes has a predetermined thickness, the first interdigital electrode is arranged such that positive and negative electrodes are alternately arranged so as to have electrode widths and periods which are gradually decreased toward the output electrode, the second interdigital electrode is arranged such that positive and negative electrodes are alternately arranged so as to have electrode widths and periods which are gradually increased toward the output electrode, and the second interdigital electrode has a double electrode structure in addition, in order to reduce ripples in frequency characteristics, the output electrode are divided into a plurality of pieces, and two end portion of each of the first and second interdigital electrodes are weighted.
11 citations
TL;DR: By anodic oxidation of the edges of the portions of the Al film under photoresist, controllable gaps between electrodes with good insulation can be obtained and applied to realize a surface-acoustic-wave (SAW) narrow gap interdigital transducer (NG-IDT) and narrow gap unidirectional transducers ( NG-UDT).
Abstract: By anodic oxidation of the edges of the portions of the Al film under photoresist, controllable gaps between electrodes with good insulation can be obtained. These techniques are applied to realize a surface-acoustic-wave (SAW) narrow gap interdigital transducer (NG-IDT) and narrow gap unidirectional transducer (NG-UDT). The experimental result shows 7.2 dB insertion loss with amplitude ripples of +or-1.2 dB for a conventional NG-IDT. Directives of 3-dB/transducer at 440 MHz (fundamental) and 13-dB transducer at 870 MHz (second-harmonic operation) for a new floating electrode type unidirectional transducer (NG-FEUDT) are demonstrated. Also a three transducer low loss filter using a combination of NG-IDT and NG-FEUDT exhibits 3.46 dB insertion loss at 894 MHz (second-harmonic operation, electrode width of 1.7 mu m) with sidelobe suppression greater than 35 dB. >
TL;DR: In this paper, the excitation of higher-order ultrasonic Lamb wave modes by an interdigital transducer (IDT) deposited on a piezoelectric plate is investigated both theoretically as well as experimentally.
Abstract: The excitation of higher‐order ultrasonic Lamb wave modes by an interdigital transducer (IDT) deposited on a piezoelectric plate is investigated both theoretically as well as experimentally. Green’s function method of analysis is used to calculate the coupling of the IDT to the various modes. This is then used to calculate the performance of a Lamb wave delay line. Experimental results obtained on delay lines fabricated on 128° rotated Y‐cut, X‐propagating lithium niobate plates are compared with theoretical calculations. The resonant frequencies and time delays of the modes are found to be in fair agreement with calculated values. It is shown that delay lines fabricated on acoustically thin plates (h/λ<1, where h=plate thickness, and λ=acoustic wavelength) can efficiently excite Lamb waves at frequencies greater than 10 times the resonant frequency of the lowest‐order mode.
Patent•
10 Dec 1992
TL;DR: In this paper, a longitudinal SAW filter in which ripple and a difference from group delay times are limited by obtaining a pass band depending on three primary - ternary vibration modes in three input/output interdigital transducer electrodes (IDT).
Abstract: PURPOSE: To obtain a longitudinal SAW filter in which ripple and a difference from group delay times are limited by obtaining a pass band depending on three primary - ternary vibration modes in three input/output interdigital transducer electrodes (IDT). CONSTITUTION: Input/output electrodes 11, 12 of nT pairs respectively are arranged on a major surface of an ST-cut crystal substrate 1 along a propagation direction of a SAW(surface acoustic wave). Furthermore, a 3rd center IDT electrode 13 of nG pairs is arranged between the electrodes 11, 12 and reflectors 5, 6 having N sets of gratings are arranged at both sides of the three IDT electrodes. The electrode finger pitch of the IDT electrodes 11, 12, 13 is identical to each other, the grating pitch of the reflectors 5, 6 is set a little larger than that of the IDT electrodes to improve the reflecting efficiency and to attain the filter with a low loss. Then the interval between the IDT electrodes is to be an integral number of multiple of the electrode finger pitch the interval between the IDT electrode and the reflector is selected to be a half wavelength of a stimulated SAW and the primary - ternary vibration modes are confined between the reflectors 5 and 6. COPYRIGHT: (C)1994,JPO&Japio
20 Oct 1992
TL;DR: In this paper, a theory for the reversing multistrip coupler (RMSC) is presented based on the previously developed spectral theory of interdigital transducers (IDTs), which shows that the track changing reflection of a surface acoustic wave (SAW) in an RMSC depends on the frequency-like reflection of SAWs from ordinary periodic grating reflectors.
Abstract: A theory for the reversing multistrip coupler (RMSC) is presented based on the previously developed spectral theory of interdigital transducers (IDTs). It shows that the track-changing reflection of a surface acoustic wave (SAW) in an RMSC depends on the frequency-like reflection of SAWs from ordinary periodic grating reflectors. The reflection to the other channel is full in a narrow frequency band of relative width 2/3 Delta nu / nu if the RMSC is sufficiently long. Some applications of the RMSC are discussed, including SAW dispersive filters, resonators and low-loss filters. A new dispersive interdigital transducer having substantial apodization that reduces spurious passband is proposed. >
Patent•
02 Jan 1992TL;DR: In this article, a surface acoustic wave apparatus with a reflector on both sides of an input interdigital transducer and an output inter-digital transducers is presented. But the reflector is not provided on the output of the inter-transducer.
Abstract: A surface acoustic wave apparatus wherein a reflector for reflecting a surface acoustic wave is provided on both sides of at least one of an input interdigital transducer and an output interdigital transducer, or, on one side of one of the input interdigital transducer and the output interdigital transducer.
20 Oct 1992
TL;DR: In this paper, a simple equivalent circuit representing the whole structure of an interdigital transducer was derived from the coupling-of-mode (COM) equations on surface acoustic wave (SAW) particle velocities, which are different from the ordinary COM equations in general use.
Abstract: A simple equivalent circuit representing the whole structure of an interdigital transducer (IDT) is derived from the coupling-of-mode (COM) equations on surface acoustic wave (SAW) particle velocities, which are different from the ordinary COM equations in general use. The difference between these two sets of equations is discussed, and another type of equivalent circuit, which consists of two imaginary gyrators connected to the acoustical ports of the previously derived circuit, is derived from the ordinary COM equations. The distinctions between these two equivalent circuit models are discussed. >
TL;DR: In this paper, the reflection of obliquely incident shear horizontal (SH) bulk acoustic waves at the interface between a piezoelectric crystal and a viscous conductive liquid is theoretically investigated.
Abstract: The reflection of obliquely incident shear horizontal (SH) bulk acoustic waves at the interface between a piezoelectric crystal and a viscous conductive liquid is theoretically investigated. In addition to viscous entrainment and mass loading effects, it is shown that the presence of a reflection‐generated external electric field offers the possibility of acoustoelectric interaction with charged particles and dipoles in the solution. These interaction mechanisms could be exploited for liquid chemical analysis and biosensor applications. Expressions are obtained for the reflection coefficients (amplitude and energy) and phase shift upon reflection in terms of the angle of incidence, wave frequency, crystal parameters, and liquid properties (density, viscosity, dielectric constant, and conductivity) by using the normal wave impedance and the input impedance of the interface. It is shown that the sensitivity of such acoustic wave detectors could be tailored by properly choosing the interdigital transducer (I...
20 Oct 1992
TL;DR: In this paper, a self-resonant SAW filter with reflecting multistrip couplers (RMSC) and unidirectional IDTs was proposed.
Abstract: Low loss high selectivity surface acoustic wave (SAW) filters realized on the basis of the self-resonance approach without the use of matching LC-networks are presented. This approach is based on input interdigital transducer (IDT) static capacitance compensation by radiation susceptance and the choice of a definite number of finger pairs. Self-resonant SAW filters are developed on the basis of a ring configuration with reflecting multistrip couplers (RMSC) and unidirectional IDTs with U-shaped multistrip couplers. The optimization of filter topologies is achieved using computer programs based on the equivalent circuit model. At 45 MHz the ring filters show insertion loss below 2 dB, 2-5% fractional bandwidth, and stopband attenuation over 50 dB. >
20 Oct 1992
TL;DR: In this paper, the effect of the electrode structure of a group-type unidirectional transducers (GUDTs) on the cutoff frequency of bulk wave radiation was studied.
Abstract: In the design of broadband low-loss group-type unidirectional transducers (GUDTs) the effect of bulk wave radiation must be considered. It influences the accurate design of the phasing network for the GUDT and increases the insertion loss. In addition, the zeros of the frequency response become less pronounced. The influence of the electrode structure of the GUDT on the cutoff frequency of bulk wave radiation is studied. The ratio of bulk wave radiation to surface wave radiation is calculated for a uniform interdigital transducer (IDT), as well as for an electrode structure of a GUDT on LiNbO/sub 3/-128rotYX, LiNbO/sub 3/-YZ, and quartz-STX. The effect of bulk wave radiation on the zeros of the frequency response is shown for several adjustments of the phasing network. >
Patent•
27 Aug 1992
TL;DR: In this paper, the authors proposed to obtain the surface wave device using an SH-type surface wave where the spurious due to a bulk wave is reduced and a package structure is simplified by emitting the formation of voids.
Abstract: PURPOSE:To obtain the surface wave device using an SH-type surface wave where the spurious due to a bulk wave is reduced and a package structure is simplified. CONSTITUTION:By providing a resin layer 13 formed on an upper surface 16a of a piezo-electric substrate 16 so as to cover an interdigital transducer, the package structure is simplified by emitting the formation of voids. Level differences 17a and 17b are provided on the end face of a piezo-electric substrate 16, end face parts 18a and 18b lower than the end faces 17a and 17b are made rough surfaces. By forming the resin layer 13 so as to cover the upper end face parts 19a and 19b, the spurious due to the reflection in the end face of the bulk wave is reduced in the surface wave device.
TL;DR: Tinel and Duclos as discussed by the authors showed that the interaction of an incident bulk wave with the dihedral in a particular direction results in a Scholte wave at the interface. But they did not show how to generate the wave in the presence of a dihedral.
Abstract: The Scholte–Stoneley interface wave is interesting in an acoustic field because it does not decay during its propagation. Different techniques have been used to generate this liquid/elastic solid interface wave. Some of these techniques are based on the conversion of an incident wave, for example a longitudinal wave in the case of the alcohol wedge method. A Scholte wave can be generated directly using an interdigital transducer (I.D.T.) deposited on a piezoelectric substrate, or an amorphous substrate covered with a thin piezoelectric film. The study of the reversibility of the Scholte wave diffraction phenomenon by a dihedral [A. Tinel and J. Duclos, Acoust. Lett. 15, 30–35] leads to the presentation of another technique to generate a Scholte wave. It has been verified that the interaction of an incident bulk wave with the dihedral in a particular direction results in a Scholte wave at the interface. This method is efficient and easy to use.
Patent•
01 Oct 1992
TL;DR: In this article, a symmetric frequency feature was obtained by eliminating the difference of the sound speed in a weighting electrode and that in a single phase one-way electrode in a surface acoustic wave filter used for a communication unit and the like.
Abstract: PURPOSE:To obtain a symmetric frequency feature by eliminating the difference of the sound speed in a weighting electrode and that in a single phase one-way electrode in a surface acoustic wave filter used for a communication unit and the like. CONSTITUTION:The weighting electrode 7 composed of an interdigital transducer 1c and a dummy electrode 6, which are provided on a piezoelectric substrate 3, and the single phase one-way electrode 8 composed of an interdigital transducer 1d and a reflector 2, which are provided on the piezoelectric substrate 3, are provided. Thus, the pitch size (m) of the interdigital transducer 1c is made longer than the pitch size (n) of the interdigital transducer 1d by a ratio between the speed of sound in the single phase one-way electrode and that in the weighting electrode, and therefore the filter feature is made symmetric.
TL;DR: In this article, a system for measuring the sound velocity in a liquid is described, which uses an interdigital transducer (IDT) for a leaky surface acoustic wave.
Abstract: A system for measuring the sound velocity in a liquid is described, which uses an interdigital transducer (IDT) for a leaky surface acoustic wave. The IDT on a piezoelectric substrate effectively operates as a radiator and a detector of the bulk wave at a liquid-solid interface. The measurement is accomplished by a frequency sweeping method under the condition of the fixed sound path length. The output curve is obtained as a function of the frequency at the IDT in the form of the interference between the input and the output signal reflected from the reflector. The measurement resolution of the present system is within 0.1%.
Patent•
23 Dec 1992
TL;DR: In this paper, a surface acoustic wave filter has a PIN diode or a mechanical switch between the filter output terminal and a second output port for the second output interdigital transducer.
Abstract: In a surface acoustic wave filter having a piezoelectric substrate (11) on which an input interdigital transducer (12) and first and second output interdigital transducers (15, 16) are disposed with the output interdigital transducers opposed to the input interdigital transducer apart therefrom, a first output port (17) for the first output interdigital transducer is directly connected to a filter output terminal (20). Between the filter output terminal and a second output port (18) for the second output interdigital transducer, a switch (22) selectively connects the second output port to the filter output terminal to make the filter output terminal produce a filtered output signal which is equal to a sum of at least one of output electric signals supplied from the first and the second output ports. The switch may be a PIN diode or a mechanical switch. The input interdigital transducer may be divided into a plurality of partial input interdigital transducers for supplying a surface acoustic wave to the output interdigital transducers, respectively. The first output interdigital transducer has a primary weighting factor while the second output interdigital transducer has a difference weighting factor.
20 Oct 1992
TL;DR: In this article, the excitation of higher-order ultrasonic Lamb wave modes by an interdigital transducer deposited on a piezoelectric plate was investigated both theoretically and experimentally.
Abstract: The excitation of higher-order ultrasonic Lamb wave modes by an interdigital transducer deposited on a piezoelectric plate is investigated both theoretically and experimentally. It is found that depending on the value of the ratio h/ lambda (h=plate thickness, lambda =acoustic wavelength), a number of higher-order modes can be efficiently excited. The phase velocity of higher-order modes is greater than the surface acoustic wave (SAW) velocity, while their group velocity is lower than that of the SAW. Thus, these modes have a higher resonant frequency and also a longer time delay than the surface acoustic wave. It is found that in acoustically thin plates (h/ lambda >
TL;DR: In this article, an ultrasonic technique is described for delecting defects that have occurred in an IC package, which uses a leaky Lamb wave device operating at a liquid-solid interface.
Abstract: An ultrasonic technique is described for delecting defects that have occurred in an IC package, which uses a leaky Lamb wave device operating at a liquid-solid interface. An ultrasonic beam, radiated into water from an interdigital transducer for leaky Lamb waves, is incident on the sample surface in an oblique direction. The incident angle is an important factor for the ultrasonic beam to transmit in the sample. The direction of the sound beam in water is varied considerably by changing the operation frequency because of the very dispersive property of the Lamb wave. The system is demonstrated as one effective means for detecting defects in an IC package, and it can select the proper operation frequency and the radiation angle of the longitudinal wave
09 Jul 1992
TL;DR: In this paper, a 2.6 GHz surface acoustic wave (SAW) filter was fabricated using an electron beam exposure system using an interdigital transducer of aluminum on piezoelectric material (LiTaO3).
Abstract: We fabricated 2.6 GHz surface acoustic wave (SAW) filters using an electron beam exposure system. The filter consists of an interdigital transducer of aluminum on piezoelectric material (LiTaO3). Since the LiTaO3 density was high, a large number of electrons were backscattered from the material when exposed by electron beams. When a conventional negative resist was used, the backscattered electrons degraded the image contrast so that resist residue remained on unexposed areas after development. The process margin, which indicates exposure tolerance, was calculated. The process margin was small for LiTaO3, indicating that it is difficult to suppress resist residue when negative resist is used and that a positive resist should be used. To obtain vertical walls of positive resist, we used a 0.4-micrometers double-layer configuration in which the upper layer had a lower sensitivity than the bottom layer. To prevent the piezoelectric substrate from breaking due to the pyroelectric effect, the resist pre- and post-baking temperature was raised gradually at a rate of 5 degrees/minute. The 0.4-micrometers line and space patterns required for a 2.6 GHz filter could be produced accurately. The fabricated SAW filter had a 2.58 GHz center frequency and an insertion loss of 5.0 dB.
TL;DR: In this paper, the phase velocity and efficiency of a leaky surface acoustic wave transducer operating at a liquid-solid boundary radiates a longitudinal wave into water were analyzed numerically.
Abstract: A leaky surface acoustic wave transducer operating at a liquid-solid boundary radiates a longitudinal wave into water. The structure of aPVDF/ interdigital transducer/fused quartz plate is analyzed numerically to understand the transducer performance including the phase velocity and efficiency for the acoustic beam radiation into water in comparison with the characteristics in a structure incorporating a piezoelectric ceramic plate instead of PVDF. The zeroth-order mode has a large transducer efficiency, although the electromechanical coupling constant is small. The results are useful in designing an ultrasonic transducer for acoustical imaging and sensor technology.
TL;DR: An ultrasonic evaluation system of soldered connections which uses a leaky Lamb wave device operating at a liquid-solid interface is described in this article, where two arched interdigital transducers on a thin piezoelectric ceramic plate are successfully demonslrated.
Abstract: An ultrasonic evaluation system of soldered connections which uses a leaky Lamb wave device operating at a liquid-solid interface is described. The leaky Lamb wave device has two arched interdigital transducers on a thin piezoelectric ceramic plate. The direction of the sound beam into water is varied considerably by changing the operation frequency because of the very dispersive property of the Lamb wave. This characteristic can be used effectively for C-mode imaging. Typical examples obtained by using a reflected wave from the back surface of the IC plate are successfully demonslrated.
Patent•
10 Jun 1992TL;DR: In this paper, an electric surface acoustic wave filter with platelet-shaped substrate of monocrystalline piezo-electric material, one substrate side of which carries interdigital transducers (IW3, IW2) with metallic electrode fingers meshing with one another in a manner of a comb and with busbars (7, 15) and (8, 9), respectively, for exciting and coupling out the surface acoustic waves, the electrode fingers of equal polarity in each case being in contact with a busbar common to these electrode fingers.
Abstract: An electric surface acoustic wave filter with platelet-shaped substrate (1) of monocrystalline piezo-electric material, one substrate side of which carries interdigital transducers (IW3, IW2) with metallic electrode fingers (4, 5) meshing with one another in a manner of a comb and with busbars (7, 15) and (8, 9), respectively, for exciting and coupling out the surface acoustic waves, the electrode fingers of equal polarity in each case being in contact with a busbar common to these electrode fingers. In this arrangement, at least one busbar (15) of an interdigital transducer (IW3) extends in a sawtooth shape at least in sections and is inclined at an angle of approximately +/- 10 DEG to +/- 20 DEG with respect to the desired direction of propagation of the surface acoustic waves in this section.