## 2 Ultrasound Generation
Different working modes:  
- Sweep mode--ultrasonic cleaners have several ultrasonic transducers, which, despite the high precision of workmanship, differ in resonant frequency. Therefore, if the generator emits a constant-frequency electric current, some transducers will not work at the resonant frequency, resulting in poor efficiency and rapid overheating. To avoid this, the generator is equipped with a special sweep mode that determines the effective fundamental centre frequency and the range of frequency variation that allows each transducer to achieve resonance. Thanks to these measures, even if for a short time, all transducers operate at their own resonant frequency, which allows for optimization of  
Figure 1: The main elements of an ultrasonic bath. the energy efficiency of the entire assembly and even distribution of the load on all elements [10]. * Full-wave mode--this is the standard single-frequency ultrasonic treatment mode for all transducers;
* Burst mode--this involves generating periods of power 50-80% higher than normal power followed by equal periods of zero power;
* Degas mode--the intensity of the ultrasound is changed over time to speed up the process of degassing the liquid;
* Impulse mode. **The ultrasonic probe**  
An ultrasonic probe system, also known as an ultrasonic horn or ultrasonic probe, is a specialized piece of equipment used for applying ultrasonic vibrations directly to a sample. It consists of the following items (Figure 2):  
* Generator--the generator produces electrical signals of a specific frequency that are sent to the ultrasonic transducer. The most common frequency is 20 kHz, but other frequencies are also available;
* Ultrasonic converter--this converts electrical energy into mechanical vibrations of fixed frequencies, usually 20 kHz;
* Probe--this transmits ultrasonic energy into a sample;
* Booster (optional)--this is used to increase the intensity of the ultrasonic vibrations. There are two primary distinctions between an ultrasonic probe and an ultrasonic bath. Firstly, an ultrasonic probe is submerged directly into the solution, while in an ultrasonic bath, the liquid has no direct contact with the ultrasonic emitter and takes the shape of the tank into which it was poured. Secondly, an ultrasonic probe supplies much higher levels of ultrasonic energy than an ultrasonic bath (sometimes even 100 times higher). These significant variations dictate the specific applications of each system. An ultrasonic probe system offers several advantages that make it a valuable tool for various applications. A probe system enables precise targeting and is flexible in use. The probe's tip can be positioned directly at the point of interest, enabling focused treatment and minimizing the impact on surrounding areas. Ultrasonic probes come in various sizes and shapes, allowing for flexibility in adapting to different sample types and volumes [11]. Another advantage is the possibility of obtaining high ultrasound intensity. This higher intensity allows for more efficient and effective sample processing, especially for challenging tasks such as cell disruption or particle size reduction. Due to its higher energy  
Figure 2: The main elements of an ultrasonic probe system. output, an ultrasonic probe system can achieve desired results in a shorter time. This is particularly advantageous for time-sensitive processes or situations where reducing the exposure of sensitive samples to ultrasonic energy is important. Ultrasonic probes are particularly suitable for small-scale processing, making them ideal for research labs, benchtop setups and applications where larger equipment is not necessary. Another advantage of this system is ease of use. Operating an ultrasonic probe system can be straightforward, especially when using modern systems equipped with user-friendly controls and displays.