Ultrasonic Measurements of Temperature in Aqueous Solutions: Why and How

Abstract

The paper describes two different approaches to ultrasonic measurements of temperature in aqueous solutions. The first approach uses two narrowband ultrasonic transducers and support electronics that form an oscillating sensor which output frequency is related to the measured temperature. This low-cost sensor demonstrated sensitivity of about 40 Hz/K at the distance of 190 mm and the operating frequency of about 25 kHz. The second approach utilised pulse-echo mode at the centre frequency of 20 MHz. The reflector featured a cavity that was filled with deionised water. The ultrasound propagation delay in the cavity was related to the temperature in the solution. The experiments were conducted for deionised water, and solutions of sodium persulfate, sodium chloride, and acetic acid with concentrations up to 0.5 M. In the experiments (conducted within the temperature range from 15 to 30• C), we observed increases in the ultrasound velocity for increased temperatures and concentrations as was expected. Measurement results were compared with literature data for pure and seawater. It was concluded that ultrasonic measurements of temperature were conducted with the resolution well below 0.1 K for both methods. Advantages of ultrasonic temperature measurements over conventional thermometers were discussed.

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

“…Although temperatures can be estimated from time-of-flight (TOF) ultrasonic measurements [13,14], oscillating architecture has been identified as a potentially lower cost alternative [15]. Ultrasonic oscillating temperature sensors (UOTSes) operate a pair of inexpensive mass-produced narrowband ultrasound transducers in the through transmission mode, and they use a positive feedback loop to sustain oscillations whose frequencies represent the sensor's output with the mechanism similar to that of acoustic feedback or used in surface acoustic wave (SAW) oscillators.…”

“…The UOTS was implemented by complementing one transducer pair with a modular ultrasonic driver [14], which consisted of two PSoC1 modules. One module was used for amplifying and band pass filtering the loop signal, and the other module was used to measure the UOTS output frequency and communicate it to the host via a suitable USB module.…”

Embedded Supervisory Control and Output Reporting for the Oscillating Ultrasonic Temperature Sensors

“…Ultrasonic NDE sensors can be used to measure and monitor various physical quantities using several arrangements of ultrasonic transducers [1,8]. More specifically, we focus our discussion on ultrasonic temperature measurements of water using two separate ultrasonic transducers fixed against each other at the boundaries of the water containing vessel (through transmission arrangement).…”

Development of an Ultrasonic Thermometry System

“…O princípio de medição de temperatura por ultrassom baseia-se na dependência da temperatura com a velocidade de propagação das ondas de ultrassom através do meio. A dependência da temperatura com a velocidade do ultrassom no meio foi relatada teoricamente pela primeira vez em 1873 por Alfred M. Mayer [5]. Experimentalmente, um dos primeiros autores a empregar ultrassom para monitoramento de temperatura foi Gilbert e colaboradores, em 1985, durante um tratamento por criogenia de carcinoma hepatocelular [6].…”