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History of Ultrasound Physics and the Properties of Transducers

Updated on July 5, 2017


Ultrasound physics refer to mechanical vibrations that go above 20 kHz. Sound travels in form of a motorized longitude wave whereby; the back and forth particle motion moves parallel to the wave travel direction. The human ear can hear any sound between 20 kHz and 20 Hz and as such scientists find it helpful in their daily endeavors. A transducer on the other hand is a device which converts a signal to another form of energy from one form of energy to another. Modern ultra sound physics is a product of many fronts of its evolution from its inception. The development of ultrasound physics has had immense benefits to humanity.


Ultrasound physics was developed more than 100 years ago through the contributions of several different individuals from different nationalities. Even though the initial ultrasound development were made by scientists from outside the medical field, these developments united to enable the medical professionals realized how to use ultrasound to detect, treat or diagnose different kinds of illness (Bruno, 2012).

Pythagoras, a Greek nationalist and scientist popular for the theory of right-angled triangles, was the pioneer of ultrasound physics. This is attributed to the fact that he invented the instrument used in learning musical sounds. Another scholar, Boethius (c. 480-c.525) gave a comparison between waves produced when a pebble drops in water and sound waves. In 1794, Lazaro Spallanzani, an Italian physiologist made another discovery when he noticed that bats fly using ultrasound in form of echolocation. In this regards, the bats make sound, receives the echo when the sound hits and bounces back from an object in front, then uses the echo to define the location and size of the object. In 1826, Daniel Jean proved that sound can travel faster in water by using a submerged bell. Pierre Curie in 1880 discovered that particular crystals developed charges on the surface when mechanical stress was applied on them, which he called the piezoelectric effect (Tsung, 2011).

In the year 1912 when the titanic sank, a hydrophone was discovered. This was the first transducer that was developed by Paul Langevin, a French nationalist and which was used to discover icebergs that were used in detecting submarine enemies in the World War 1. Later in 1948, an internist by the name Ludwig George used ultrasound physics to explain how he detected and diagnosed foreign objects such as gallstones in the human body. This trend continued as more and more scientists discovered that ultrasound can be used for detecting and diagnosing then treating several human illnesses. As technologies continued to be developed and discovered by scientists based on their necessity, the basis of modern ultrasound was being formed slowly. A significant part of the ultrasound development which is in use in the contemporary society is the transducer. A transducer contains a sensor and an associated circuit which converts physical signals to proportionate electrical signals ((Agarwal and Lung, 2011). The subsequent part highlights the properties of transducers.

Properties of Transducers

A transducer has two major parts namely the transduction and sensing parts. The later refers to the part that senses and responds to the physical part of the transducer while the former refers to the part that converts non-electronic to electrical signal. The transduction element receives the output of the sensing element before converting it to electrical signal. In a few cases, the transduction element performs both the actions of the transduction and the sensing parts. For instance, a thermocouple is a device used in generating voltage (Agarwal and Lung, 2011). Now a thermocouple generates voltage consistent to the heat produced at the junction of two divergent elements particularly metals. The selection of a transducer to use is a very significant factor to consider since the right transducer will give the right results and vice versa (Winer, 2013).

A transducer is selected depending on such factors as order of accuracy to be obtained, physical quantity that has to be measured or the best the principle for any given physical input. Additionally transducers can be classified based on the method used for conversion of non-electric to electric signals, the application of the transducer, whether the transducer is passive or active, the electrical parameters which may be changed due to the entire process, and the output of electrical signal that is produced by a single transducer.

The kind of transducer to be used depends largely on the on the depth of the element to me imaged. In this light, high frequency transducers will produce more clear images than low frequency but will not go deep enough where as low frequency transducers will give less clear images but penetrate more deep. Contemporary transducers are made either made of multi-element rays or piezoelectric rays


To the larger extent, the discovery, development and use of ultrasound and transducer as evident in the above discussion has in several ways impacted the lives of human and animals alike. The value of ultrasound physics can be seen by humanity in its unrelenting refinement which includes the continued transformation and use of the transducer. The transducer technology has grown to be more refined such that ultrasound can easily be used with portable equipment in remote areas at the point of care.


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