Preparation Model And Experimental Of Low Frequency Ultrasonic Excitation For Submillimeter Microspheres

Microspheres as a nov el drug carrier ar e widely used in clin ical treatm ent,microbiology and other fields, because of th eir characteristics of absorption easily,flow smoothly and target. The conventional microsphere preparation technologies arenot suitable for submillimeter nor m icron microspheres. In this work, we com bineultrasonic excitation crushing m ethod with carrier for preparing m icrospheres.Submillimeter microspheres that are smaller than nozzle can be obtained by adjustingthe flow ratio of jet and carrier. The m ain work of this paper is to establish the theorymodel of ethyl cellulose cr ushing when the je t velo city ranges from0to30m/s,besides complete the device of ultrasonic excitation crushing in the presence of carrier.The content of this paper includes the following aspects:1. The developm ent of m icrospheres prep aration technologies is described indetails and the chara cteristics, worki ng principle and technical fra mework ofexcitation microspheres prepar ation technology is elaborat ed. Mechanical vibrationsare delivered to the jet through the ultrasonic transducer, at the same time，the carriersqueezes and pulls the jet. The cons tant jet breaks into uniform droplets, and for msmicrospheres when the droplets fall into the collection fluid.2. The connection m ode of injection needle with transform er is improved on theexisted dev ice. According to th e charac teristics of m icrospheres preparationtechnology, carrier structure is designed and the holes of carrier plate can be adjustedto the nozzle easily.3. Based on the VOF model of the FLUE NT software, using the dynam ic meshmodel and user defined functi on, the periodic disturbance is realized and the processof jet breakup is simulated. Through the simulation, jet velocity ranges from8to m/sand frequency varies from15kHz to70kHz and the amplitude increases from8um to30um are studied, besides the m orphology of microspheres are got at different flowratio.4. The material is discussed. Based on the ultrasonic excitation device with carrier,using ethyl cellulose, the diam eter and standard deviation of microspheres is studiedwhen flow ratio varies. The data shows that the diameter of m icrospheres isequivalent to the nozzle diameter when the flow ratio is1.5. Also, the cause of bigger standard deviation is analyzed.