ULTRASOUND wave is a kind of WAVES with the frequency higher than the human audible frequency. Although ULTRASOUND was first used for military identification purposes, it has been used for decades for various other applications, especially medical applications. Medical applications of ULTRASOUND include diagnostic and therapeutic applications, such as for the treatment of cancer. In this paper, for the first time, electrostatically-actuated micro-speakers made of a dielectric elastomer (DE) have been used to generate and focus the ultrasonic WAVES using Micro-Electro-Mechanical Systems (MEMS) technology. The results have shown that a single micro-speaker could not generate an efficient focused wave, so an array of the micro-speakers has been considered. The layout of the micro-speakers is a square array of Bessel Panel. It has been shown that by adopting a suitable excitation frequency as well as number of the elements in the Bessel’ s panel, the DE-based capacitive micro-structures can focus the generated sound wave in a pre-determined area.

Background: In order to quantify effects of ULTRASOUND irradiation parameters under therapeutic condition, especially sonodynamic therapy, it is initially necessary to evaluate inertial cavitation activity in vitro conditions; therefore, in this study, the effect of 1 MHz low level ULTRASOUND based on °OH radicals generated by acoustic inertial cavitation in aqueous solution was monitored by their reaction with terephthalic acid (TA) to produce fluorescent 2-Hydroxyterephthalate acid (HTA) by spectrofluorometry method (Terephtalic acid dosimetry). Materials and Methods: The study was designed to measure hydroxyl radicals in a field near to 1 MHz sonotherapy probe in progressive mode and low level intensity. The effect of ULTRASOUND irradiation parameters (1MHz) containing duty factor, mode, intensity ULTRASOUND and, time sonication in hydroxyl radical production have been considered. After preparation of solution of dosimetry and plotting calibration curve of spectrofluorescence, the effect of mode of sonication (continuous and pulsating), duty factor (20-80%), intensity (0-2 W/cm2, with step of 0.5 W/cm2), and sonication time (0-60min with step time of 10min) without increasing temperature to more than 3°C to determine the effective exposure in low level ULTRASOUND were evaluated. The fluorescence intensity of TA solution before and after irradiation, in all cases was measured, and the results were reported as Mean ± Standard Deviation (SD). Results: The result of experiments related to sonication mode for 1MHz ULTRASOUND irradiation (2 W/cm2) show that continuous mode of sonication is 29% higher fluorescence intensity than the pulse mode in 80% duty cycle for sonodynamic therapy. With compensation of irradiation time for 1MHz sonication in different duty cycles, fluorescence intensity in continuous mode is 22% higher than the pulse mode in average. The amount of hydroxyl radicals production versus ULTRASOUND intensity, and sonication time show with increasing intensity or sonication time in continuous mode, the hydroxyl radical production is linearity increased (R=0.99). Conclusion: The results show that the terephthalic acid dosimetry is suitable for detecting and quantifying free hydroxyl radical as a criterion of inertial cavitation production over a range of condition in medical ULTRASOUND fields.  

Background: ULTRASOUND WAVES are considered non-invasive, safe, and mechanical stimuli with unknown mechanisms.Objective: The aim of this study is to determine the effect of acoustic cavitation interaction according to the mechanical index (MI) on fibroblast cells’ reproducibility and gene expression of collagen Ι as a skin repair agent.Material and Methods: In this interventional study, the ultrasonic pressure equations were solved to extracted the maximum mechanical indices with frequencies of 150 kHz, 40 kHz, 28 kHz and low intensity (<0.5 W/cm2). Groups were extracted with a mechanical index of 0.10, 0.20, and 0.40. Then, fibroblast cells were exposed to selected acoustic parameters from simulation. After 5 days, the proliferation was measured with an MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay, and collagen Ι expression was quantified.Results: Increasing reproducibility in the groups of 0.23 W/cm2 with 0.20 mechanical index threshold was calculated at 1.70±0.05 and 1.07±0.04 times higher in continuous and pulse modes compared to the control group. Reducing the proliferation in group 0.40 mechanical index was shown as compared with control and sham groups in pulse mode (P-value<0.05). The collagen Ι expression level of fibroblast cells in groups of control and 0.20 MI were 0.03±0.00 and 0.17±0.05, respectively. The acoustic vibration effects at 0.20 mechanical index have promoted fibroblast cell functions. Conclusion: Low-frequency and -intensity ULTRASOUND WAVES on the mechanical index threshold (cavitation threshold) increases the proliferation of fibroblast cell and the expression of collagen type Ι.

Humic substances mainly humic acids constitute the major fraction of natural organic matter in water supplies. They play an important role in the formation of harmful disinfection by products. Degradation of humic acids by means of ultraviolet radiation and ultrasonic irradiation processes was investigated in a laboratory-scale batch photoreactor equipped with an 300 W immersed-type medium-pressure mercury vapour lamp and sonoreactor with low frequency (42 kHz) plate type transducer at 170 W of acoustic power with emphasis on the effect of various parameters on degradation efficiency. Experiments were performed at humic acids initial concentrations varying between 2.5-10 mg/L. Oxidation of humic substances has been followed over time by measuring total organic carbon and UV absorbance in 254 nm and 436 nm. Initial results indicated a strong capacity of photolysis for degradation of humic substances. The results also showed that ultrasonic alone cannot be an efficient method for degradation of humic substances in comparison with UV process. The maximum degradation efficiency of humic substances after 90 min of irradiation, however, was only 5.7% and reached a maximum value of 9.5% after 300 min of irradiation. It was found that total organic carbon can be removed effectively by photolysis. It was also found that lower concentrations of humic substances favor the humic substances degradation. Also, the experimental results indicated that the kinetics of ultrasono-oxidation and photo-oxidation processes fit well by pseudo-first order kinetics.