Advanced Piezo Disks Driving Innovation with Limitless Applications

Piezo Disks Transforming Vibrations Innovation

Piezo disks are widely used in daily life as key components in numerous technological products. These devices possess unique properties: when deformed by an external force, they generate an electrical signal; conversely, when a voltage is applied, they undergo deformation. Thanks to this bidirectional physical characteristic, the Piezo disk can serve both as a sensor—detecting variations in various physical quantities—and as a sound-producing element, converting electrical energy mechanical energy to perform multiple functions.
In the field of sensors, one common application is the piezo pickup. The Piezo disk directly senses minute sound vibrations and converts them electrical signals for subsequent audio processing. For instance, pickups in electric guitars utilize the piezoelectric effect to transform string vibrations electrical signals. Additionally, Piezo disks can be employed in raindrop sensors, where the small vibrations caused by raindrops striking the disk are used for sensing, enabling real-time weather monitoring. Sound detectors represent another typical application, as they can detect changes in ambient sound and are widely used in security monitoring and smart home systems.

Wearable Medical Products Shaping the Future of Health Management

Portable medical products have become a new trend in health management. These devices emphasize portability and multifunctionality, allowing users to monitor their health status anytime and anywhere. Take blood glucose meters as an example; for diabetic patients, regularly tracking blood sugar levels is crucial for maintaining health. Modern blood glucose meters not only need to measure blood sugar levels accurately but also utilize Piezo disks to emit sound or vibration alerts, clearly indicating when a measurement result is available or when further action is required (Figure 1).

Figure 1. Schematic diagram of the application of the Piezo disk in a blood glucose meter.
The application of piezo disks in these devices enhances both user experience and safety. When users perform blood glucose tests or insulin injections, sound alerts ensure correct operation and help prevent health risks caused by improper dosages. Additionally, other wearable medical devices—such as heart rate monitors and sleep trackers—extensively utilize piezo disks to detect physiological signals, providing precise data analysis. With this real-time health information, users can manage their health more effectively and seek timely medical assistance when necessary. 

Key Specifications of Piezo Disks for Wearable Devices

To ensure integration wearable devices, the Piezo disks used are typically 20?mm in size. Their primary operating frequency generally starts at around 3500 Hz, and their impedance ranges from approximately 250 to 1000 ohms (based on Piezo disks with diameters between 12 and 20?mm). The ceramic surface is usually made of ceramics without a printed feedback point; in combination with the metal substrate, the total thickness is approximately 0.25?mm. The metal commonly used for these Piezo disks in product applications is brass, which often offers a cost advantage.

Figure 2. Schematic diagram of the impedance analysis of the Piezo disk.

Taking the Piezo disk shown in Figure 2 as an example, its frequency sweep (20 Hz to 20 kHz) is different from a speaker’s curve. A speaker’s curve is usually flat, meaning the sound pressure is similar across a range (e.g., 1 kHz to 10 kHz). In contrast, the Piezo disk only shows a high sound pressure peak at its resonance point (e.g., a single point at 4 kHz). When you move slightly away from the resonance frequency, the pressure drops sharply.
Thus, for acoustic applications, you can use the frequency band around 4 kHz. For sensor applications, you might consider using the 19 kHz band, which is beyond what humans can hear. Using this higher frequency for long periods will not make users feel uncomfortable.
Regarding the driving circuit for the Piezo disk, the industry employs a single-crystal circuit as the main driving circuit (see Figure 3).

Figure 3. Schematic diagram of the buzzer's single-crystal circuit.
Regarding Kingstate's Piezo disk products, we offer a diverse range of customizable solutions. The following products are Kingstate's Piezo disks known for their reliable delivery and consistent quality. Please feel free to contact our sales team if you have any needs.