Sensor data fusion for responsive high resolution ultrasonic temperature measurement using piezoelectric transducers.

Ultrasonic temperature measurement allows for responsive measurements across an entire ultrasonic pathway, unlike most conventional temperature sensors that respond to the temperature at the point of their placement only after a notable response time. The high cost of required ultrasonic instrumentation can be reduced substantially by using ultrasonic oscillating temperature sensors (UOTS) consisting of inexpensive narrowband piezo transducers and driving electronics. An UOTS produces sustained oscillations at a frequency that relates to the temperature of the medium between the transducers.

Ultrasonic sensing of temperature of liquids using inexpensive narrowband piezoelectric transducers.

We investigated the possibility of substantially reducing the cost of minimally invasive ultrasonic non-destructive evaluation (NDE) of liquids, in particular, temperature sensing, using inexpensive narrowband transducers. Although designed for operation in air, ultrasonic transducers enclosed in an aluminum case could be submerged in water and were found to be suitable for this application; however, their responses changed substantially when submerged. The test cell developed was complemented by an amplifier to operate as an oscillator and some other support electronics to supervise the sensor's operation.

Ultrasonic monitoring of foamed polymeric tissue scaffold fabrication.

Polymeric tissue scaffolds are central to many regenerative medicine therapies offering a new approach to medicine. As the number of these regenerative therapies increases there is a pressing need for an improved understanding of the methods of scaffold fabrication. Of the many approaches to processing scaffolds, supercritical fluid fabrication methods have a distinct advantage over other techniques as they do not require the use of organic solvents, elevated processing temperatures or leaching processes.

High-accuracy data acquisition architectures for ultrasonic imaging.

This paper proposes a novel architecture for a data acquisition system intended to support the next generation of ultrasonic imaging instruments operating at or above 100 MHz. Existing systems have relatively poor signal-to-noise ratios and are limited in terms of their maximum data sampling rate, both of which are improved by a combination of embedded averaging and embedded interleaved sampling. "On-the-fly" pipelined operation minimizes control overheads for signal averaging.

Errors and uncertainties in the measurement of ultrasonic wave attenuation and phase velocity.

This paper presents an analysis of the error generation mechanisms that affect the accuracy of measurements of ultrasonic wave attenuation coefficient and phase velocity as functions of frequency. In the first stage of the analysis we show that electronic system noise, expressed in the frequency domain, maps into errors in the attenuation and the phase velocity spectra in a highly nonlinear way; the condition for minimum error is when the total measured attenuation is around 1 Neper. The maximum measurable total attenuation has a practical limit of around 6 Nepers and the minimum measurable value is around 0.

New architectures for feedthrough SAW recursive devices.

This paper presents an analysis of a new type of feedthrough recursive surface acoustic wave (SAW) device. The device combines a conventional SAW structure with positive feedback in a way that allows use of selective properties of the SAW structure, control of the central frequency and bandwidth, achieving significantly higher quality factors for given dimensions of the structure, and reduction of the sidelobe level. Several possible implementations are discussed from a simple one that uses external circuitry to the most advanced that includes digital supervisory control.

The influence of fabrication errors on the stopband magnitude responses of SAW devices.

This article is devoted to the analysis of the influence of manufacturing errors on the magnitude responses of surface acoustic wave (SAW) devices. Analytical analysis of these random errors provides statistical distributions of the relevant responses and their parameters. It allows significant reduction in the modeling computations compared to the Monte Carlo method, and it provides possibilities for further analytical analysis.