## 4 Discussion  
The study demonstrates a feasible thermal treatment for breast tumors with the combination of noninvasively fuzzy-integrated HIFU and PAI system. Compared to current methods, the proposed approach presented an affordable HIFU design for biomedical applications and a feasible imaging modality using laser and ultrasound to minimize the thermal injury during treatment. The HIFU system consists of the function generator and the power amplifier was organized by the microcontroller in a compact design. The electrical technique with very low output impedance was employed to diminish the presence of the impedance matching circuit before applying for HIFU transducer. The changeable operating frequency and output power were highly suitable for numerous therapeutic applications. The indigenous control interface was also easily accessible to users. A slight overshoot in the electrical output signals from the HIFU circuit due to the current surge during sudden MOSFET switching event (shown in Figure 6), acceptable for functioning fuzzy logic control. There were six different power levels produced by the HIFU system from 10 W to 50 W corresponding to the output voltage amplitude from \(\pm\)6 V to \(\pm\)21 V. With higher amplitude, the HIFU transducer generates the higher maximum target temperature. The strongest power delivered the most energetic acoustic pressure which enables temperature rising to a threshold of \(64.9\pm 0.26\)\({}^{\circ}\)C within 50 s (shown in Figure 7). With temperature feedback from the thermocouple, the closed-loop fuzzy controller was implemented to maintain the \(60\pm 4\)\({}^{\circ}\)C temperature by modulating the output power during the treatment (Figure 8b). Figure 9 indicates the thermal effect of HIFU treatment in ex vivo chicken breast tissue, with the coagulation area linearly expanded with the exposure time. After 300 s of the  
Figure 10: PA images of tumor-injected chicken breast tissue in ex vivo HIFU treatment: tumor images (**a**) Before and (**b**) After treatment PA images (**c**) Before and (**d**) After treatment (**e**) PA amplitude (**f**) 3D image of the treated area according to the color scale. HIFU treatment, the tissue coagulation area was 89.38 \(\pm\) 9.1 mm\({}^{2}\), which was substantially greater than those at 60 s (13.5 \(\pm\) 2.5 mm\({}^{2}\)). The HIFU system with fuzzy logic control was able to maintain a constant target temperature. Present state-of-the-art studies only apply to a single preset temperature and need to be upgraded for a set of constant temperatures to tackle the unknown upcoming demands [41; 42]. Previous studies have presented that contrast agent-assisted PAI was able to optically mimic the tumor [38]. The current study suggests a customized high-resolution PAI system guiding for artificial tumor treatment with the HIFU system. In Figure 10b, the tumor phantoms were sensitive with 532-mm laser wavelengths, so the PAI system could display a PA image of target regions even if the amplitude was not so strong. The appearance of the bright regions in Figure 10d, which represents the stronger PA signals, after the treatment process was probable evidence of the effectiveness of HIFU therapy in ex vivo experiments with phantom models. Depending on the significant differences among PA signals from both the untreated and treated regions, they were definitely separated, and the treated areas were effortlessly defined. Despite the feasibility of the proposed fuzzy-controlled HIFU-PAI combined system; this study shows several limitations. Although the current HIFU system could deliver considerable acoustic intensity to affect target tissues, the electrical output signal should be refined to remove the overshoot phenomenon. The maximum acoustic intensity of H-148 HIFU transducer (46,161 W/cm\({}^{2}\)) could be achieved if the electrical system is capable of generating a high amplitude bi-polar squared output signal without noise.