Digital Transducer Research Articles

Anti-plane waves in a liquid-loaded piezo-flexo-electric layered model with interface energy

The basic design of a Love wave (LW) bio-sensor contains the loading of a viscoelastic liquid on top of a layered structure with distinct viscoelastic properties. Changes in the characteristics of the propagating acoustic wave caused by biochemical interactions at the sensing area can be detected at the output Inter digital transducer (IDT). The propagation of the anti-plane (AP) wave is discussed in this work in a layered structure of piezo-flexo-electric (PFE) layer bonded with a PFE half-space having a soft reinforced layer at the interface. The free surface of the PFE layer is loaded with viscous liquid. The viscosity of the loaded liquid introduces losses and results in the damping of the wave. For the formulation of the problem with interface energy, the Gurtin–Murdoch approach is used. Using suitable conditions, a dispersion relation for propagating waves is derived in complex form. On separating the dispersion relation in real and non-real parts, the expressions relating the phase and damp velocities with wave number are derived. The obtained theoretical results are portrayed for the numerical data of PFE materials and distinct data of the interface layer. The obtained results are validated with pre-existing literature.

Design of heterostructure one-port SAW resonator with improved bandwidth using Si and LiNbO3 layer

In this research work, we have designed a heterostructure one-port surface acoustic wave (SAW) resonator. The multi-layer one port SAW resonator is made of a silicon (Si) substrate as base material, 128 ͦ rotated Y-cut X- propagated lithium niobate (LiNbO3) as piezoelectric substrate, and Inter Digital Transducers (IDTs) made of aluminium. This model is designed to operate on a wide frequency of 4–5 GHz with a resonance frequency of 4.74 GHz. Various parameters are taken into consideration during the study and analysis such as high-quality factor, wider bandwidth, better electromechanical coupling coefficient, and a true Figure of merit (FoM). The obtained Quality factor and the electromechanical coupling coefficient (k2) of the designed model are 2700 and 0.18. By using the wide range of frequencies, the bandwidth for the designed model is 1.74 MHz. The obtained results show that the device’s performance of the one port multilayer SAW resonator using the Al/128°YXLiNbO3/Si multi-layered substrate exhibits a commercial application in the 5 G wireless communication system.

A Perturbed Asymmetrical Y-TypeSheathless Chip for Particle Control Based on Adjustable Tilted-Angle Traveling Surface Acoustic Waves (ataTSAWs).

The precise control of target particles (20 µm) at different inclination angles θi is achieved by combining a perturbed asymmetric sheathless Y-type microchannel and a digital transducer (IDT). The offset single-row micropillar array with the buffer area can not only concentrate large and small particles in a fixed region of the flow channel, but also avoid the large deflection of some small particles at the end of the array. The addition of the buffer area can effectively improve the separation purity of the chip. By exploring the manufacturing process of the microchannel substrate, an adjustable tilted-angle scheme is proposed. The use of ataTSAW makes the acoustic field area in the microchannel have no corner effect region. Through experiments, when the signal source frequency was 33.6 MHz, and the flow rate was 20 µL/min, our designed chip could capture 20 µm particles when θi = 5°. The deflection of 20 µm particles can be realized when θi = 15°–45°. The precise dynamic separation of 20 µm particles can be achieved when θi = 25°–45°, and the separation purity and efficiency were 97% and 100%, respectively.

All-Suture Anchor Repair of the Flexor Digitorum Profundus Insertion: A Biomechanical Comparison of 2 Suturing Techniques

We compared 2 suturing techniques for reattachment of the flexor digitorum profundus (FDP) via all-suture anchor. We used fresh, matched-pair, cadaveric hands. We disarticulated the fingers at the proximal interphalangeal joints, preserving the proximal FDP. We released the FDPs at their distal insertion and placed an all-suture, 1.0-mm anchor at the center of each FDP footprint. Each anchor's sutures were used to reattach each FDP using 1 of 2 techniques: group H (n= 14) via horizontal mattress; group H+ K (n= 12) via horizontal mattress with knots thrown and, with each suture tail, 3 proximal, running-locking, Krackow-type passes on the radial and ulnar FDP sides with the suture ends tied together. We excluded 2 specimens from the H+ K group because of improper anchor placement. All other fingers in both groups were individually mounted in an MTS machine for FDP loading in the following sequence for 500 cycles each: (1) to 15 N to simulate passive motion forces; (2) to 19 N for short-arc active motion forces; and (3) to 28 N for full active motion forces. Specimens that had not failed during cyclic testing were then loaded to failure. We measured FDP-to-bone gapping via a digital transducer. We defined failure as >3-mm gapping. The H+ K group had significantly less gapping during cyclic loading up to 19 N and significantly higher load to failure. The H+ K group failed exclusively at the anchor-bone level; the H group failed mostly by suture-tendon pullout. The H+ K group performed significantly better regarding cyclic and load-to-failure testing after FDP reattachment. The H+ K technique combines the benefits of horizontal-mattress tendon-to-bone apposition and Krackow-tendon locking. It converts the point of failure to the bone level rather than the suture-tendon level.

Beyond GHz optical frequency up-converted modulation of LEDs with integrated acousto-optic transducer.

Traditional visible light communication (VLC) via light-emitting diodes (LEDs) employs the on-off keying (OOK) modulation scheme. Even though optical frequency modulation has many advantages, it is hardly used for LED VLC because a high carrier frequency cannot be applied to the LED cavity due to the resistance-capacitance limit. Here, by monolithically integrating an LED with an integrated digital transducer, we experimentally demonstrate the intermixing of gigahertz surface acoustic waves and electrical data signals in the LED cavity at room temperature. An optical transmitter was realized by in situ frequency up-conversion of the data signals from an LED, which has the advantages of improving transmission performance by up-shifting the data spectrum away from low-frequency noise. Our proposed integrated acousto-optic transducer opens a new developing scheme on the frequency up-mixed data encoding of an LED beyond its inherent modulation bandwidth for future VLC.

Ladder Type of Leaky Surface Acoustic Waves Filters on Substrate of Lithium Niobate

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

A simple and novel SAW magnetic sensor with PVA bound magnetostrictive nanopowder film

•In this paper a Surface Acoustic Wave (SAW) magnetic field sensor based on magnetostriction effect was realized using a simple, inexpensive and novel approach. A single port SAW resonator on ST-Quartz substrate was used and configured as a Colpitt Oscillator. A novel coating approach was adopted whereby a thin layer of Polyvinyl Alcohol (PVA) was coated on bare SAW device to passivate and electrically isolate the Inter Digital Transducers (IDTs) followed by thin layer of PVA nanocomposite magnetostrictive coating applied using drop dry method. Separate sensors were realized using Nickel (Ni) and Iron (Fe) materials and their performances were evaluated using a Helmholtz coil. Good magnetic sensitivity and repeatability was observed in developed sensors. Excellent long term stability was achieved and no fatigue was observed.

Ultrasonographic Detection of Interstitial Nephritis in a Canine Fetus

Background: A detailed ultrasound examination of the fetal urinary tract as part of prenatal care is important to detect possible abnormalities. Early diagnosis can prevent more serious damage such as loss of kidney function. Interstitial nephritis can compromise renal functionality. Also, acute interstitial nephritis is a frequent cause of acute kidney injury and can become chronic if not treated. Besides, a renal biopsy can help in the diagnosis and at the staging of the disease. Therefore, this report aims to describe the ultrasonographic findings of the renal tissues in a canine fetus affected by interstitial nephritis.Case: Gestational ultrasound evaluations were performed in a female Pug, at the 25th, 45th, and 58th gestational days. Ultrasound examination was performed with a 9.0 MHz linear transducer and a high-resolution digital transducer with a frequency standardized at 17.0 MHz. During the first evaluation, embryonic vesicles were detected and were compatible with the gestational period. At 45 days of gestation, some abnormalities were observed in the kidneys of one of the fetuses, such as increased cortical echogenicity, cortical thickening, loss of corticomedullary ratio (1:1), renal pelvis and ureter dilatation by echogenic content. Biparietal and abdominal diameters were also lower than that from the other fetuses, which did not show abnormalities, being compatible with the estimated gestational age. However, the heart rate was similar among all fetuses. On the 58th day, we observed in the underdeveloped fetus that both kidneys still presented the abnormalities seen previously, in addition to the presence of a cystic structure in the right kidney, in the cranial topography of the cortex. The other fetuses kept showing normal ultrasonographic findings, normal heartbeat, all of these compatible with the ultrasound gestational age. The delivery occurred without complications and only the underdeveloped fetus stillborn. Then, it was submitted to a necropsy where chronic interstitial nephritis was found in the histopathological analysis.Discussion: Adequate prenatal care is important to detect abnormalities in fetuses, in which ultrasound examination allows to access fetal development. The gestation in the bitch seemed to be occurring without complications, but the B mode and High Definition ultrasound techniques were able to identify abnormal development of the fetus' kidneys. Both techniques showed to be secure to the fetuses and the mother, as they are non-invasive and free of radiation. These findings, different from those described as normal for a fetus, reinforce the warning signal for a possible establishment of anomalies consistent with nephropathy. Still, histopathology is important to exclude other diseases and help to define prognosis. Interstitial nephritis can significantly affect perinatal survey, considering that the fetus was stillborn, confirming that the description of such anomalies can help to prevent disease. Since nephritis can be associate with the use of some medicines, the orientation of the owner regarding drug use during bitch pregnancy is essential. Therefore, this is the first report describing renal abnormalities in a canine fetus, which highlights the importance of ultrasound examination for disease identification in prenatal care. Lastly, high-resolution ultrasound (HD) could provide detailed information on abnormalities in the fetal kidney.

(Invited) High-Sensitive Electrochemical Detector with Micro-Stirrer Driven By Surface Acoustic Wave

Micro total analysis system (μTAS), by applying microfabrication technology used in the manufacture of semiconductor integrated circuits, applies chemical processing and biochemical analysis usually conducted using test tubes in a laboratory to microscopic flow paths fabricated on a chip, and it is an ultra compact analytical system.Advantages of μTAS are that it requires only a small amount of sample used for measurement, the space in the groove is narrow, so that the diffusion distance of molecules can be shortened, the reaction time can be shortened, automation of measurement including pretreatment, miniaturization of the equipment, disposable of the equipment, low cost, reduction of manpower and the like can be cited.If μTAS is put into practical use, it is expected that everyone can easily and accurately inspect on site. However, as μTAS uses extremely small samples such as tens of microliters, the issues such as handling difficulty and reproducibility remain. Turning to the electrochemical sensor, electrochemical measurement is effective as a detection method in μTAS because it has advantages such as fast response, inexpensive, easy to miniaturize, and so far, many electrochemical biosensors have been reported. Generally, in the electrochemical measurement, based on the electron transfer between the analyte on the electrode surface and the electrode, the analyte is detected from the current value. In the analysis with a sample volume of several milliliter scale, the agitator is placed in the solution cell and stirring is carried out, whereby the supply to the electrode surface of the measurement analyte is enhanced, whereby high sensitivity can be detected. However, μTAS can not place a stirrer because it uses a small amount of tens of microliters, and it is difficult to stir manually, the diffusion of the detection analyte to the electrode surface becomes rate-limiting, causing a decrease in sensor sensitivity. Therefore, in this research, we focused on an actuator using surface acoustic wave (SAW) in order to solve the problem that sensor sensitivity decreases in electrochemical measurement of a small amount of sample. Surface acoustic waves are vibrations that concentrate and propagate on the surface of an object and can be generated by applying a high frequency potential to the IDT (Inter digital transducer) fabricated on the surface of the piezoelectric substrate. IDT can be easily fabricated by conventional photolithography technology. Since surface acoustic waves can be driven by microscale pattern electrodes fabricated by microfabrication, they are suitable for handling a very small amount of liquid droplets. Many reports have been reported as droplet flow manipulation techniques by using SAW. In the field of biotechnology, application to PCR with enhanced reaction efficiency of trace amounts of samples has been reported. Many researches have also been reported in which SAW is applied as a conversion element of a biosensor. A detection method by label free is proposed by measuring the frequency shift due to adsorption to the sensor surface. In recent years, co-authors reported a technology to place a small amount of 5 μL droplets in the pool and drive them by SAW. They also studied the relation between the power supplied to the IDT and the angular velocity and temperature of stirring the liquid using the SAW driven micro liquid rotor.If we could fuse this SAW technology with electrochemical measurement and stir a small amount of sample, diffusion of the target substance to the electrode surface increased, and we thought that we could solve the problem of sensitivity reduction due to diffusion control. In this research, we propose a novel measurement system which electrochemical detection is carried out by integrating 3 electrode system for electrochemical detection on SAW substrate developed by bicycle, and stirring minute amount of sample by SAW. As a result, it is possible to increase the diffusion rate of the analyte in the small amount sample to the electrode surface, aiming at constructing an electrochemical detection system with high sensitivity and good reproducibility. Figure 1

Trapping cell spheroids and organoids using digital acoustofluidics

The precise positioning and arrangement of cell spheroids and organoids are critical to reconstructing complex tissue architecture for tissue engineering and regenerative medicine. Here, we present a digital acoustofluidic method to manipulate cell spheroids and organoids with unprecedented dexterity. By introducing localized vibrations via a C-shaped integrated digital transducer (IDT), we can generate a trapping node to immobilize cell spheroids with a diameters ranging from 20μm to 300μm. Moreover, we digitally trapped multiple cell spheroids atop the C-shaped IDTs within a closed or open microfluidic chamber. By programming the trapping nodes within a 3 × 3 C-shaped IDT array, we can precisely position cell spheroids into designed patterns. We also demonstrated that our digital acoustofluidic device can accurately control the interaction of spheroid cells and organoids. Along with a simple fabrication procedure and setup, our digital acoustofluidic method can provide precisely manipulate and position various cell spheroids or organoids in a contactless, label-free, and highly biocompatible manner. We believe this technology can be widely used for tissue engineering, regenerative medicine, and fundamental cell biology research.

Hydroacoustic evaluation of the spatial and temporal distribution of fish in the upstream proximity of a dam in a Neotropical reservoir

Background. Construction of dams alters the physical, chemical, and ecological characteristics of the aquatic environment and modifies fish behaviour and the community composition. Few studies have shown the diel and seasonal fish distribution in tropical reservoirs, mainly in the proximity of the dam, where the risk of injury and death of fishes, which try to migrate downstream, is high. Thus, the data obtained in these regions can encourage actions that may attenuate the impacts on ichthyofauna. Hydroacoustic sampling is an effective tool to study fish behaviour and their spatial distribution in water bodies. In this context, the aim of this study was to evaluate the spatial and seasonal distribution of fish in the reservoir of Três Marias (Minas Gerais, Brazil), immediately upstream of the dam, using hydroacoustic and gillnet sampling. Materials and methods. Hydroacoustics and gillnet sampling were carried out both during the day and at night, and during the rainy and dry seasons. For the acquisition of hydroacoustic data, we employed an echosounder (BioSonics DT-X Digital Scientific) with a split-beam digital transducer. For the biological data, gillnets of different mesh sizes were set. Results. Hydroacoustic data showed significant differences in fish depth between day and night surveys, with fish remaining in deeper water during the day, a phenomenon known as Diel Vertical Migration. Furthermore, hydroacoustic data showed that smaller fish (estimated by “target strength”) concentrate at smaller depths. There was no significant difference in the size of fish between seasons. Limnological and operation variables were not related to the fish  abundance. Distribution maps showed that during the day fishes were distributed in areas more distant from the dam, while at night they were closer to the dam. Gillnets sampled 127 individuals of 22 species and 57.5% of the collected specimens were migratory species. Conclusion. These results can contribute to the understanding of fish behaviour in reservoirs, as well as provide an empirical basis for the development of novel fish management measures for Neotropical dams.

Efficient Vehicle Testing

The enhanced functions of the digital transducer interface from Kistler enable the measurement of more than 280 channels with a single cable

Fabrication of micro-cantilever and its theoretical validation for energy harvesting applications

An effort has been made to develop a micro-cantilever using MEMS technology for the realization of piezoelectric energy harvester. For the fabrication of micro-cantilever, a membrane of SiO2 of thickness 1.8 μm has been integrated with piezoelectric PZT thin film and gold inter digital transducers (IDTs). MEMS based micro-cantilever with three different dimensions having cantilever lengths of 200 μm, 300 μm and 400 μm have been designed and fabricated for the realization of energy harvesters. The actuating frequency has been found to be varying with length of cantilever. The experimentally observed resonating frequencies of all prepared piezoelectric cantilevers have been validated with the theoretical simulations carried out using COMSOL multiphysics software.

Reproducible multi-parameter acoustic detection of seasonal drift macroalgae in the Indian River Lagoon, Florida

Biennial single-beam dual-frequency acoustic surveys of Indian River Lagoon, a coastal Florida lagoonal system, were performed to quantify the spatial distribution of the annual peak of seasonal drift macroalgae (DMA) as part of the Surface Water Improvement Program (SWIM) enacted in 1986. The ultimate goal of SWIM was to reclaim historical seagrass acreage. Dense accumulations of DMA can ultimately shade seagrass beds and create anoxic zones via decomposition, especially during warm summer months, thus contributing to the internal nutrient pool. A large portion, approximately 140 km of the Indian and Banana Rivers, were surveyed at 200 m line spacing within the timeframe of peak DMA biomass (April through June). A supervised training catalog of 180 60-s acoustic and video samples was grouped into classes of bare substrate, short (canopy) submerged aquatic vegetation and DMA and segmented by discriminant analysis using a combined 38 and 418 kHz dataset. Percent cover of DMA was binned into categories of 0–33, 33–66 and 66–100%. Consistent classification of training catalog samples collected in 2007, 2008 and 2010 validated the temporal consistency of BioSonics digital transducers, meaning the previous surveys training dataset can be used to produce a preliminary map with only a few days lag-time, and that year-to-year acoustically-derived DMA abundances can be directly compared without bias adjustment. DMA biomass within the 288 km2 survey area was 69,000 and 102,000 metric tons wet weight in 2008 and 2010, respectively with an overall classification accuracy of 78.9 and 83.2%, respectively. Four large-scale deposits were detected in the same locations during both surveys but the majority of biomass came from widespread sparse deposits. DMA was found to decompose within the IRL rather than exiting through Sebastian Inlet. The high abundance of DMA in 2010 and subsequent release of nutrients within the IRL was vital for understanding the 2011 superbloom.

Effect of Radiant Energy on the Formation of Optical Image in X-Ray Inspections

Digital radiography is currently a genuine alternative to the laborious and uneconomical method of X-ray diffraction in nondestructive testing. The processes of forming optical images on a radiographic film and on a flat-panel detector are different. The input action on a detector, whether a radiographic film or a digital transducer, is the so-called radiation image, the X-ray radiation generated by an X-ray tube and transmitted through a test object. The object attenuates radiation depending on its own thickness and material density. The main parameters of the radiation image are its contrast, definition, and signal-to-noise ratio (SNR). In order to achieve the most efficient conversion of the X-ray image into an optical one, one needs to choose the optimum combination of the listed parameters depending on which detector is being used. In this study, theoretical research and practical evaluation of its results have been carried out. Conditions have been determined for the best adaptation of a radiation image to the employed detector that ensure the prescribed quality indicators of the optical image of the test object. Results of the research that was carried out within the framework of scientific field 2.3 “Developing methods for automated nondestructive testing and the reliability of its results” (“Strategic directions of development of materials and technologies of their processing for a period of up to 2030”) are provided.

Frequency response improvement of a two-port surface acoustic wave device based on epitaxial AlN thin film

This paper presents an exploration on improving the frequency response of the symmetrical two-port AlN surface acoustic wave (SAW) device, using epitaxial AlN thin film on (0001) sapphire as the piezoelectric substrate. The devices were fabricated by lift-off processes with Ti/Al composite electrodes as interleaved digital transducers (IDT). The impact of DL and the number of the IDT finger pairs on the frequency response was carefully investigated. The overall properties of the device are found to be greatly improved with DL elongation, indicated by the reduced pass band ripple and increased stop band rejection ratio. The rejection increases by 8.3 dB when DL elongates from 15.5λ to 55.5λ and 4.4 dB further accompanying another 50λ elongation. This is because larger DL repels the stray acoustic energy out of the propagation path and provides a cleaner traveling channel for functional SAW, and at the same time restrains electromagnetic feedthrough. It is also found that proper addition of the IDT finger pairs is beneficial for the device response, indicated by the ripple reduction and the insertion loss drop.

A comparative evaluation of chewing efficiency, masticatory bite force, and patient satisfaction between conventional denture and implant-supported mandibular overdenture: An in vivo study.

Purpose:The purpose of this within-subject crossover clinical trial was to compare and evaluate the chewing efficiency, masticatory bite force, and patient satisfaction with conventional dentures and two implant-retained mandible overdentures after 4 weeks of usage.Method:This within-subject crossover clinical trial was carried out in the Department of Prosthodontics in K.D Dental College and Hospital. A total 15 patients were selected for the study. To report the changes in chewing efficiency by chewing 6gms of peanuts with 40 chewing strokes and comparing the particle size of the chewed material between two implant retained mandibular overdenture with that of conventional denture using micro vu excel gantry type visual measurement machine. To report changes in masticatory bite force after transition of conventional complete denture patient to implant retained overdenture after using the prosthesis for four weeks each and recorded by digital transducer. To assess the patient satisfaction after transition of conventional complete denture patient to implant retained mandibular overdenture with help of OHIP edent patient satisfaction questionnaire.Results:The chewing efficiency for implant retained overdenture increased significantly than that of conventional denture. The particle size decreased to 76.34% for implant supported overdenture than that of conventional denture. The chewing strokes required by conventional denture was 69 strokes and that by implant supported overdenture which was 40 strokes to get the same mean particle size. The patients satisfaction after receiving the implant retained overdenture was significantly higher than that of complete denture.Conclusion:The provision of two mandibular implants significantly improves measures of oral function and better quality of life for edentulous patients.

Pressure Measurement and Traceability at NIS- Egypt

Pressure sensors, transmitters and transducers are widely used for measuring and controlling the pressure. Tracing of measurement of such pressure sensing instrumentation is very important in many industrial applications. Calibrations of pressure instruments with acceptable uncertainty tracing to the SI units are required. This study aims to study the propagation of uncertainty from SI units through primary standard piston cylinder assembly (PCA) up to 500 MPa. The hierarchy of pressure measurements at NIS is based on using large effective area PCA in defining the pressure of 1 MPa. Primary standard PCA characterization and evaluation are presented then transferring the obtained results to other pressure traceability level is described. Calculation and propagation of uncertainty starting from primary standard to digital pressure gauges, digital pressure calibrators, pressure sensors and pressure transducers were investigated.

Prosthetic Aortic Valve Fixation Study: 48 Replacement Valves Analyzed Using Digital Pressure Mapping.

Prostheses attachment is critical in aortic valve replacement surgery, yet reliable prosthetic security remains a challenge. Accurate techniques to analyze prosthetic fixation pressures may enable the use of fewer sutures while reducing the risk of paravalvular leaks (PVL). Customized digital thin film pressure transducers were sutured between aortic annulus models and 21-mm bioprosthetic valves with 15 × 4-mm, 12 × 4-mm, or 9 × 6-mm-wide pledgeted mattress sutures. Simulating open and minimally invasive access, 4 surgeons, blinded to data acquisition, each secured 12 valves using manual knot-tying (hand-tied [HT] or knot-pusher [KP]) or automated titanium fasteners (TFs). Real-time pressure measurements and times were recorded. Two-dimensional (2D) and 3D pressure maps were generated for all valves. Pressures less than 80 mm Hg were considered at risk for PVL. Pressures under each knot (intrasuture) fell less than 80 mm Hg for 12 of 144 manual knots (5/144 HT, 7/144 KP) versus 0 of 288 TF (P < 0.001). Pressures outside adjacent sutures (extrasuture) were less than 80 mm Hg in 10 of 60 HT, zero of 60 KP, and zero of 120 TF sites for 15 × 4-mm valves; 17 of 48 HT, 25 of 48 KP, and 12 of 96 TF for 12 × 4-mm valves; and 15 of 36 HT, 17 of 36 KP, and 9 and 72 TF for 9 × 6-mm valves; P < 0.001 all manual versus TF. Annular areas with pressures less than 80 mm Hg ranged from 0% of the sewing-ring area (all open TF) to 31% (12 × 4 mm, KP). The average time per manual knot, 46 seconds (HT, 31 seconds; KP, 61 seconds), was greater than TF, 14 seconds (P < 0.005). Reduced operative times and PVL risk would fortify the advantages of surgical aortic valve replacement. This research encourages continued exploration of technical factors in optimizing prosthetic valve security.

Pencel Pressuremeter Efficiency for Data Compilation and Analysis

The model Pencel pressuremeter (PPMT), manufactured by Roctest, Inc is used to perform PPMT tests in various soils to allow engineers to more precisely carry out the consistent tests. Therefore, the control unit of the PPMT has been implemented to allow recording digital pressures and volumes. This digital information is now obtained through a standalone software package, called Automated Pressuremeter (APMT) that incorporates the required calibrations to provide engineers with instantaneous reduced data along with pertinent engineering strength and stiffness properties. The study objective is to simplify test data, reduction and analysis which lead to significant time saving. Several tests data for sands and clays were performed for accuracy and incorporated in the comparison. A linear potentiometer was connected directly to the piston to produce digital volumes, while, a digital pressure transducer was coupled into the control unit. For each injected volume increment the pressure versus time data was estimated to determine when the pressures stabilized. APMT indicated that the pressure stabilized between 10 and 80 seconds for soils evaluated. The volume increment stabilization period was defined as the time required for the pressures to stabilize. This digital equipment enhanced the precision of the pressures more than ten fold and eliminated gear backlash associated with the existing volume counter.