High-Power Piezoelectric Ceramics: The Core Component Behind Modern Atomization and Ultrasonic Cleaning

Introduction
Medical micro-dose drug delivery, high quality smart home products containing inbuilt control mechanisms of humidifiers and aroma diffusers and ultrasonic precision manufacturing (centered on ultrasonic cleaning technology in the manufacturing industry) are the three industries that are expanding rapidly at present. One need that these industries have in common is that it is necessary for them all to use piezoelectric ceramics that can reversibly withstand high frequency vibrations, without fouling, lose performance over time and overheating.
This type of material is referred to as a "high-power" piezoelectric ceramic. This group of components is seeing a surge in demand that is gaining momentum and is expected to continue its upward trend over the coming years. Not always, however, has the quality of supplies matched the demands. Standard grade ceramics continue to be sourced by many manufacturers and it is only when the products fail after strenuous service in the field that they find the ordinary materials just weren't meant for that kind of load.
It is not a buying decision to select an appropriate piezo elements supplier. It is a product strategy. How long your device lasts, how dependable it is and how successful your product on the market is depends on the material in the core of your transducer.

Why Ordinary Ceramics Fail Under High-Power Conditions
Conventional ceramics are surpassing their performance in high-power applications. Here's why ordinary ceramics are not up to the job of high-power applications.
You can't overlook this widespread issue in the industry.
A simple piezoelectric ceramic element is suitable for low power applications and for intermittent operation. It can drive in the motion when it receives electrical signals, which has an acceptable efficiency. However, if one has to push the same material into continuous, high frequency, high amplitude operation, then a series of failure modes crop up.
The first is heat. Dielectric loss of a ceramic means that it will heat up internally when stressed for a long time. Unfortunately, ceramics as is normal, have a relatively high internal loss and therefore run hot. In the material crystal structure is gradually relaxed under the influence of heat, that is, its piezoelectric constant is gradually pulled down. In practical terms, the output of the vibration system would decrease, regardless of the power level you had applied to your device, as time passed with the operation of your device. Performance drifts.
The second is electrical breakdown. Under high drive voltages, the electric field stress between the ceramic can be over the material's ability to withstand it. The ceramic is then fractured locally, potentially compromising the integrity of the element. This is not acceptable to medical devices or precision industrial equipment.
The third one is known as mechanical fatigue. The high amplitude, high frequency ceramics are subjected to real mechanical stress in every cycle. Microcracks or mismatching in materials caused by manufacturing make them stress concentration areas. After a number of cycles it fails at that point.
Here are not just hypothetical risks, these are actual ones. The answers to why ceramic element life and repeatability are always trouble spots for engineering teams in B2B manufacturing companies when they buy ceramics from a non-expert supplier.

Section One: Atomization Applications and What They Demand from Piezoelectric Ceramics
The atomization market is evolving rapidly and demands are evolving as well. Today, when engineers are looking for a suitable piezoelectric ceramic for a nebulizer they have three priorities, first, being able to control the droplet size to the micron level; Second, the device's power consumption must be reduced at the highest possible output rate;  Third, its biocompatibility for use in medical grade nebulizers.
The inverse piezoelectric effect is the mechanism used by a piezoelectric ceramic atomizer. If an alternating voltage is applied to the ceramic, the ceramic also expands and contracts at the alternating voltage frequency. For ultrasonic atomizers, the ceramic is attached to a mesh membrane containing thousands of minute holes. The ceramic vibrator produces a vibration that occurs at the same frequency as the mesh, which is in the range of 100kHz to 3MHz generally depending on the application. This oscillation produces pressure pulses that drive liquid through the holes of the mesh, and pulverizes it to create small droplets on the opposite side.
The mesh hole diameter and vibration frequency have a significant influence on the droplet size. However, the uniformity of those droplets across the mesh's surface and the performance of the atomizer; what it can do from one hour to the next relies on the ceramic element behind them.
A good ceramic for atomizer should have a constant resonant frequency even under other conditions, It encounters during the atomizer operation including when it is hot. It should have a high electromechanical coupling coefficient, to achieve greater mechanic's power output from the electrically applied power input, with less input power wasted as heat. It must be equal in every unit it goes through in a batch, for each new unit that comes off the assembly line must have the same effect.
There is one other requirement for medical devices with atomizers: The ceramic material should be biocompatible because any contaminants transferred to the liquid path will be transferred to the patient's respiratory system. Consequently, there are a number of requirements that must be placed on the materials that are employed in the formulation of the ceramic and on any bonding agent employed to construct the transducer.

Section Two: Ultrasonic Cleaning and the Strictest Requirements in the Industry
One side of the piezoelectric ceramics market is atomization while the other is ultrasonic cleaning. The requirements for performance are higher, conditions are tougher and the consequences of failure are more severe.
In the electronics industry, semiconductor wafer cleaning, precision optics, aerospace parts cleaning and luxury watch manufacturing are among the uses for cleaning in industrial ultrasonic cleaning. The expectation for the "cleaning standard" is extremely high for all of these situations. 
Engineers in this class for finding ultrasonic cleaning transducer elements are concerned with three specifications: High Mechanical Quality Factor, Low Dielectric Loss and Long Periods of large vibration amplitude where, without cracks or frequency drift, the vibrator can maintain large amplitude oscillations for long periods of time.
For three reasons, these are important.
High Mechanical Quality Factor is called mechanical quality factor and measures the ratio of the vibration energy generated to the mechanical energy converted into vibration, rather than dissipated as heat, in the resonating ceramic. A high Qm is indicative of the ceramic rings working effectively at its resonant frequency. This is equivalent to powerful and stable cavitation in a cleaning tank, when microscopic bubbles of cavitation in the cleaning fluid violently scour the contaminants from the surfaces. A low Qm produces more heat, less cavitation, which will result in less cleaning and a ceramic that will overheat.
Measuring how much of the electrical energy used to excite the ceramic was lost as heat within the ceramic, is the use of tan delta. High loss ceramics, even at low power level operate on a hot condition. A continuous duty industrials cleaning system that operates for 8 hours or more reduces the life of the transducers with time due to this heat accumulation that progressively damages the ceramic.
It is large vibration amplitude which actually causes cavitation. However, ceramics are brittle. When the ceramic is pushed at high-amplitude, any material defect, such as an air pocket, a density variation or an uncontrolled grain boundary as a result of the sintering process turns into the initiation site of cracking. For cleaning situations, highest quality ceramics are made with super tight manufacturing tolerances at each stage of the measuring process from the powder preparation, to the sintering and polarization process.
For industrial customers, it's a no-brainer. A transducer specifically designed with the wrong ceramic substrate, will not perform as well as intended on the first day and may fail sooner than planned, causing an interruption of production. If the ceramic specification is understood at the design phase, then it's all avoided.

Bestarsensor: Technical Depth Built Through Years of Focused Work
Bestarsensor is a manufacturer who's years familiar with this field, high-power piezoelectric ceramics for tough applications.
The company is knowledgeable from the material level. Bestarsensor has created proprietary ceramic types, specifically designed for high power installations. That is to say, formulations can be designed with higher Qm, lower dielectric loss and crystal structures which continue to have the same piezoelectric constant over a broad temperature range and significantly over long periods of continuous usage. 
Bestarsensor also has the production facilities to help supply high quantities of B2B products. They have a complete acoustics&electrical testing lab. All production lots are specified prior to shipment and data is analyzed to ensure uniformity within lot. 
In addition to the product lines, Bestarsensor has proven its capability of making the custom ceramic formulation for application requirements. If your design requires a frequency that is not available in a catalog part, or if your operating environment demands unusual stresses of a thermal mechanical nature, the engineering staff can work with you to create a material specification to meet a specific need.
This is the mix of both material knowledge and manufacturing prowess and engineering assistance that sets a true long term supply partner apart from a parts distributor. Bestarsensor acquire this competence over the years, and with longstanding experience delivering products to manufacturing customers in a wide range of industries in large volume.
If you want to build a competitive advantage from the product development stage, choosing the right materials is often the best place to start.

Conclusion
The piezoelectric ceramic that sits at the heart of your transducer can't be sold at random. Whether you are buying one for the use of a medical nebulizer, a home fragrance system or a cleaning system for semiconductors or a precision washer in your industrial processes, you are not buying a commodity. It is obviously a technical issue and matters deeply to the performance, reliability and in turn, your reputation with the customers of your product.
The long product life, stable output and resistance to real-world operating conditions without degradation are built on the foundation of high performance, high stability piezoelectric ceramics.
Bestarsensor provides good material quality, batch uniformity and engineering assistance required for serious manufacturing operations, high power piezoelectric ceramic elements. Whether you are doing a project at the design stage or assessing your supply chain, Bestarsensor is at your service. Provide us with your frequency, power and dimensions, we will give you a technical evaluation and competitive quote. Call on Bestarsensor to discuss with a piezoelectric application engineer today.