It’s a Small World – Designing Piezoelectric Acoustic Transducers as Devices Miniaturize, Part 1

The increasing miniaturization and sophistication of electronic products–ranging from consumer media devices, to medical diagnostic tools, to defense-related sonar applications–presents a bounty of utility and ease for consumers, and an ongoing challenge for design engineers. These seemingly disparate products (audio/mobile device speakers, certain non-invasive medical devices and sonar arrays) share in common a reliance on piezoelectric transducers to both generate and receive acoustic signals.

Sound Waves

Piezoelectric materials have been valued since the first half of the 20th century for their ability to convert mechanical energy into electrical energy and vice versa. However, 21st century technology demands that these same materials produce more sound or more precise frequencies within smaller and smaller packages–all while utilizing as little energy as possible. The challenge of designing piezoelectric-containing devices is inherently Multiphysics in nature due to the confluence of electricity, vibration and acoustics, and designers must have tools that can calculate the multiple physics within their products.

Piezoelectric Material Overview

Piezoelectric materials are materials that can produce electricity due to mechanical stress, such as compression. These materials can also deform when voltage (electricity) is applied. Typical piezoceramic materials are non-conductive ceramic or crystal that are placed between two metal plates.

For piezoelectricity to be generated, the material needs to be compressed or squeezed. Mechanical stress applied to piezoelectric ceramic material generates electricity. The piezoelectric effect can be reversed, which is referred to as the inverse piezoelectric effect. This is created by applying electrical voltage to make a piezoelectric crystal shrink or expand. The inverse piezoelectric effect converts electrical energy to mechanical energy.

Piezoelectric materials are found in a surprising array of everyday products. The flame that leaps to life when you press the button of a “click-and-flame” lighter was aided into existence by the compression of piezoelectric material, which produces a spark.

Next, we will take a look at some other products that present more of a challenge for design engineers due to the need for increased output within smaller devices. Read Part 2.