Monolithic ultrasound fingerprint sensor.

This paper presents a 591×438-DPI ultrasonic fingerprint sensor. The sensor is based on a piezoelectric micromachined ultrasonic transducer (PMUT) array that is bonded at wafer-level to complementary metal oxide semiconductor (CMOS) signal processing electronics to produce a pulse-echo ultrasonic imager on a chip. To meet the 500-DPI standard for consumer fingerprint sensors, the PMUT pitch was reduced by approximately a factor of two relative to an earlier design. We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor. The resulting 110×56-PMUT array, composed of 30×43-μm2 rectangular PMUTs, achieved a 51.7% fill-factor, three times greater than that of the previous design. Together with the custom CMOS ASIC, the sensor achieves 2 mV kPa-1 sensitivity, 15 kPa pressure output, 75 μm lateral resolution, and 150 μm axial resolution in a 4.6 mm×3.2 mm image. To the best of our knowledge, we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints

Ultrasonically bonded value assembly

A valve apparatus capable of maintaining a fluid-tight seal over a relatively long period of time by releasably bonding a valve member to its seat is described. The valve member is bonded or welded to the seat and then released by the application of the same energy to the bond joint. The valve member is held in place during the bonding by a clamping device. An appropriate force device can activate the opening and closing of the valve member. Various combinations of material for the valve member and valve seat can be utilized to provide an adequate sealing bond. Aluminum oxide, stainless steel, inconel, tungsten carbide as hard materials and copper, aluminum, titanium, silver, and gold as soft materials are suggested

Critical sound attenuation in a diluted Ising system

The field-theoretic description of dynamical critical effects of the influence of disorder on acoustic anomalies near the temperature of the second-order phase transition is considered for three-dimensional Ising-like systems. Calculations of the sound attenuation in pure and dilute Ising-like systems near the critical point are presented. The dynamical scaling function for the critical attenuation coefficient is calculated. The influence of quenched disorder on the asymptotic behaviour of the critical ultrasonic anomalies is discussed.Comment: 12 RevTeX pages, 4 figure

The influence of long-range correlated defects on critical ultrasound propagation in solids

The effect of long-range correlated quenched structural defects on the critical ultrasound attenuation and sound velocity dispersion is studied for three-dimensional Ising-like systems. A field-theoretical description of the dynamic critical effects of ultrasound propagation in solids is performed with allowance for both fluctuation and relaxation attenuation mechanisms. The temperature and frequency dependences of the dynamical scaling functions of the ultrasound critical characteristics are calculated in a two-loop approximation for different values of the correlation parameter $a$ of the Weinrib-Halperin model with long-range correlated defects. The asymptotic behavior of the dynamical scaling functions in hydrodynamic and critical regions is separated. The influence of long-range correlated disorder on the asymptotic behavior of the critical ultrasonic anomalies is discussed.Comment: 12 RevTeX pages, 3 figure

Depth of Cracking beneath Impact Craters: New Constraint for Impact Velocity

Both small-scale impact craters in the laboratory and less than 5 km in diameter bowl-shaped craters on the Earth are strength (of rock) controlled. In the strength regime, crater volumes are nearly proportional to impactor kinetic energy. The depth of the cracked rock zone beneath such craters depends on both impactor energy and velocity. Thus determination of the maximum zone of cracking constrains impact velocity. We show this dependency for small-scale laboratory craters where the cracked zone is delineated via ultrasonic methods. The 1 km-deep cracked zone beneath Meteor Crater is found to be consistent with the crater scaling of Schmidt (1) and previous shock attenuation calculations

Pneumatic PID with Ultrasonic Distance Feedback

Indiana University Purdue University IndianapolisIndiana University–Purdue University Indianapolis (IUPUI) is initiating a new course to the Electrical & Computer Engineering Technology (ECET) Curriculum in the spring of 2019, this course is Advanced Process Controls. The lab curriculum for this course needed a functional application to demonstrate the use of a proportional–integral–derivative controller (PID). The lab location for this course has one important limitation, specifically no use of water; therefore, our design integrates the use of pneumatics. Using the lab’s existing Rockwell Automation PLC and software package, this design uses the PLC’s PID instruction to maintain an extension length on a pneumatic single acting cylinder. This closed control loop consists of the PLC and analog I/O card, an ultrasonic distance sensor, one pneumatic cylinder for the controlled variable, one pneumatic cylinder as a disturbance, and two Proportion-Air QB1X analog controlled pneumatic solenoids. The final design in summary, uses the ultrasonic sensor to provide feedback to the PID with the current extended length of the pneumatic cylinder. This establishes any error, and the properly tuned PID uses this feedback to respond accordingly to ensure the desired extension length of the cylinder is maintained.Electrical Engineering Technolog

Shear and longitudinal viscosity of non-ionic C12E8 aqueous solutions

We present measurements of the steady shear viscosity, the longitudinal elastic modulus and the ultrasonic absorption in the one-phase isotropic liquid region of the nonionic surfactant C12E8 aqueous solutions. The overall results support the presence of two separated intervals of concentration corresponding to different structural properties. In the surfactant-rich region the temperature dependence of the steady shear viscosity follows an equation characteristic of glass-like systems. The ultrasonic absorption spectra show unambiguous evidence of viscoelastic behaviour described by a Cole-Cole relaxation formula. In the water-rich region the behaviour of the measured quantities are more complex and reflect the presence of dispersed aggregates whose size increases with temperature and concentration. An additional low frequency contribution is also observed, which is ascribed to the exchange of water molecules and/or surfactant monomers between the aggregates and the bulk solvent region.Comment: 23 Pages, 7 Figures, 1 Table, submitted to J. Phys. Chem B, accepted for publicatio