Piezoelectric components are integral parts of products ranging from microphones to quartz watches and inkjet printers to tuning forks. They power many of the devices we rely on in our daily lives. But what is piezoelectricity, and how has it developed over the centuries into the sophisticated technology we know today?
The root piezo comes from the Greek piezein, which means “to press.” The verb signifies physical pressure — piezoelectric sensors, then, detect physical pressure or stress.
Piezoelectric history began in the 1880s when the young French scientists Pierre and Jacques Curie discovered the piezoelectric effect.
These two physicists were particularly interested in the pyroelectric effect, which had been well known to scientists for some years. The pyroelectric effect occurs when a temperature change in a crystal causes an electric potential. The Curie brothers were interested in learning whether physical stress, like pressure or vibrations, could also produce an electric charge on a crystalline surface.
The brothers used materials like glue, tin foil, magnets and wires to create experiments to test the properties of different crystalline structures, including quartz, tourmaline, topaz, sugar and Rochelle salt. After applying mechanical pressure to these materials, they found quartz and Rochelle salt showed the most significant electrical piezoelectric effects.
Armed with that knowledge, they built the first piezoelectric quartz electrometer. Later, they also discovered the piezoelectric effect could work in reverse. That is, applying an electrical force to crystals can cause them to change shape as if from the application of physical force.
These experiments paved the way for many future advances in science and technology, including the development of the piezoelectric sensors used in health care scanners, fuel injectors, ultrasonic transducers on submarines and many more products.
In 1910, the German physicist Woldemar Voigt published an enormous volume of material, “Lehrbuch der Kristallphysik,” detailing the known piezoelectric materials and their properties. He listed the twenty or so crystals that generated an electric field in response to pressure, and he also worked out and defined the mathematical coefficients that quantified the amount of electrical change produced with an application of physical pressure.
This book’s publication paved the way for practical applications of the piezoelectric effect. Knowing of the existence of the effect and the relevant properties that produced it had made for exciting science. Voigt’s work provided the data and math necessary to use the piezoelectric effect in useful ways.
During World War I, the French scientist Paul Langévin, until then a theoretical physicist, turned his attention to how applied physics might aid in the war effort. He used quartz’s piezoelectric properties to develop technological advancements for submarines, famously inventing the first device that could use echolocation to locate submarines in the ocean. This device, the quartz sandwich transducer, represented the first sonar technology.
Unlike later sonar devices, this one used passive listening only. It could not send out its own signals for use in detection the way later active sonar devices could. Additionally, Langévin’s breakthrough came too late to make a dramatic difference in the war effort. Nevertheless, French citizens and Americans both relied heavily on his theories after the war. This development provided the critical groundwork necessary for further sonar development and designs.
The successful introduction of sonar technology spurred the scientific community to more research and experimentation with piezoelectric materials. During World War II, scientific groups in the United States, the Soviet Union and Japan discovered that some ceramic materials exhibited the same piezoelectric properties already known in crystals — but with dielectric constants up to 100 times greater. These ceramics, known as ferroelectrics and created by sintering powdered metallic oxides, turned out to be relatively easy to manufacture.
Scientists around the world turned their attention to how they could better harness ceramics and ferroelectrics to improve military technology. In developing piezoceramics and their applications, the compound barium titanate (BaTiO3) proved useful as a base for creating the necessary ceramic material. However, barium could not always achieve uniform impedance characteristics, and the more stable lead zirconate titanate (PZT) has now replaced barium titanate in many applications.
Using the resulting piezoceramics, research groups successfully developed new technologies like more sophisticated sonar systems, ignition devices, microphones and audio transducers.
In the later decades of the 20th century, the commercial market for piezoelectric materials expanded significantly. As manufacturers developed newer devices, they relied more and more on advanced piezo products. Soon enough, piezoelectric materials made their way into many consumer devices. These included devices with sensors and audible alarms, such as smoke and intrusion alarms, automobiles, etc. as well as ultrasonic transducers such as level sensors, cleaners, and actuators. Piezoelectric materials also allowed for the development of smaller, more convenient electronic items.
Today, piezoelectric materials find use in a wide array of commercial and industrial products — the global market for piezoelectric devices stood at about $27.6 billion in 2019 and will likely rise to $34.7 billion by 2025. Piezoelectric devices are essential in applications like these:
The medical industry often uses piezo products in ultrasonic transducers. These are essential components in tools like ultrasound probes and other monitoring and diagnostic devices, as well as sensors used during ultrasonic surgery.
The security and defense industries often use piezo products in sound transducers, found in devices like accelerometers, pressure sensors, microphones and force sensors. They may measure aircraft noise in a wind tunnel, detect vibrations during engine testing, locate submarines and vessels, track battlefield movements and even trigger certain explosives and munitions.
The auto industry uses piezo products in components like fuel injector sensors, pressure sensors and proximity sensors in driving aids like backup cameras. Piezoelectric technology is also useful in the robotic tools that place automotive parts to ensure precision and correctness.
To see the benefits of piezoelectric components for your business, partner with APC International.
Our company has been in business since 1986, so we have the long-term industry knowledge and expertise to get you the right components for your applications. We value our working relationships and take pride in getting our customers the products they need when they need them.
We offer various services, including custom manufacture of piezoelectric components to your precise specifications, as well as in-house assembly of completed products. We use soft- and hard-body lead-zirconate-titanate composition to create an extensive catalog of products, including stack actuators, amplifiers, air transducers, ultrasonic power transducers, piezo buzzers and disc benders. We can also help you choose the right piezoelectric material to meet your business’s unique piezoelectric requirements.
For more information about our wide range of piezoelectric products and services, visit our knowledge center or contact us today.
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