Acoustoelectronic system for high intensity focused ultrasonic radiation forming aiming nanoand microsized containers opening

Background and Objectives: The aim of the study is to develop a system intended to the controlled release of preparations that were encapsulated to micro- and nanochambers. The system also allows to implement the optoacoustical diagnostics of the object by means of short light pulse radiation with the successive processing of the appeared ultrasonic signal. Short description: The system consists of two parts: electronic and acoustical ones. The electronic part represents a radiofrequency generator of electromagnetic radiation. The generated electromagnetic signal is modulated by short pulses with varying duration and duty cycle. The output electromagnetic power might be tuned in a wide range. The central frequency of the generated RF signal corresponds to the resonant frequency of a piezoelectric transducer and is equal to 2.5 MHz. The acoustical block of the system consists of the table with the bath at the top as the place for investigating a biological object. In the centre of the bath with immersion liquid (water) there is a hole with the dividing window between two parts of areas filled with the water. That window is transparent for the light and for the sound. The area under the window represents the tunable piston that allows to shift mechanically the focus plane of the acoustical transducer up and down so that to localize the area of high density ultrasound in a desirable area of a biological object. The piezoelectric transducer represents a segment of the spherical shape layer of piezoceramic having the silver electrodes on both surfaces. The electrodes are electrically connected to the RF generator by means of a coaxial cable. In coaxially to the spherical transducer the optical waveguide with microlens on its end is situated. That optical channel allows to irradiate the investigated area by short light pulses so that to provide the generation of an ultrasonic signal for opto-acoustical investigation. Results: Applying the developed system the experimental opening of microcapsules of alginate beads has been demonstrated. The results of time dependence of alginate microcapsules (beads) opening versus the concentration of silver (Ag) in the beads have been presented. Conclusion: The developed system can be used in a wide range of application aiming both the opto-acoustical investigation of objects and HIFU acting to micro- and nano chambers for releasing the encapsulated preparations.