Research For The Ultrasonic Microsphere Granulator Prototype

Nowadays, medicament microsphere is widely used in many fields such as cytology, immunology, biology and clinic diagnosis & treatment and so on. More and more, the microsphere preparation technology is attached importance to having developed a kind of availability installation, due to which preparation functions are provided with micro-diameter controlled, similitude granularity in shape and size, as well as lower cost. Capillary Vibration Method (CVM) is a kind of process to made microsphere, which is especially suitable for doing research at laboratory or small batch production. Like these have occurred in foreign country, but there are no such ones in China.There is a set of installation for microsphere preparation basing on CVM with Electromagnetic Vibration Exciter (EVE), which is an achievement of cooperation between our research group and Institute of Chemical Engineering. Through a lot of experiments test, some problems appear that are the lower effective frequency of the vibration source (EVE) and the lower efficiency of this installation. In order to solve these problems, the paper presents a new-style Ultrasonic Microsphere Granulator and researches on the CVM regularity with Ultrasonic Exciter.The paper's content includes four aspects as follows:(1) In this paper, it is presented that the medicine jet-breaking rule accords with the Rayleigh Mode. The medicine jet falls to pieces, which is disturbed by a man-induced exciter with a characteristic of controllable frequency, amplitude and mode. The most unstable wavelength of a disturbance imposed on a jet surface isλ_max= 9.016_rj.(2) The ultrasonic vibration system design mainly includes ultrasonic exciter and ultrasonic power supply. The research chooses a longitudinal-vibration piezoelectric transducer with a resonance frequency at 42kHz, and designs the exponential horn with amplification coefficient Mp=6.25. Half-bridge circuit is adopted to ultrasonic power supply with automatic tracking frequency and adjustable power.(3) Having finished the measuring and controlling system basing on ARM7 MCU LPC2132. And it comes true that both tracking ultrasonic frequency and adjusting the pressure in storage tank are controlled automatically.(4) Done experiments show the outcome which is the linear relation between jet velociti's square (V²) and pressure in storage tank (P). The data of microsphere diameter is analysed to know: the medicine jet-breaking with velocity 5⁷.5m/s is around the most unstable frequency at the spontaneous disturbance state, rather than at 42 kHz by exciter (cameo nozzle r=0.055 mm). At last, to sum up some influence of parameters such as jet velocity, jet orifice radius, vibration method and most unstable frequency.