Process Research On Piezoelectric Micro-droplet Jetting Technology Of Biomaterials

Tissue engineering, also known as regenerative medicine, usually refers to the use of bioactive substances, through in vitro culture or construction of the way, re-repair or repair tissue and organ technology. With the continuous progress of related technologies,tissue engineering has been constructed from the initial cell-free single biomaterials to a more complex and realistic multi-cell microenvironment. Bio-3D printing, as the most important tissue engineering in vitro construction technology, there is a great need for greater breakthrough in print accuracy, controllability and cell survival control in print bodies.In this paper, the application of piezoelectric jet 3D printing in tissue engineering was explored. The vibration modes of different piezoelectric actuators are analyzed, and ceramic-copper composite componentischoosed as the actuator of the diaphragm piezoelectric printhead which is optimized designed as conical section. The structure of the conventionalsqueeze-mode inkjetprinthead is researched and the energy loss in the process of injection and the reason why the high-viscosity material can not be ejected are analyzed. With optimized designthe newly squeeze-mode inkjetprinthead is able to jetthe biomaterial of a higher viscosity. Both piezoelectric printhead are matched with removable glass nozzle which is generated by a micropipette puller.We choose positive pressure in the backpressure systemfor the printhead to enhance its jetting capacity and stability. A lowframerate CCD camera is used to build a high-speed microdroplet detection system based on the improved stroboscopic delay technique.The experimental research on the jetting process and the driving parameters of the printhead is carried out. Therefore biomaterials with variety of viscosity were tested by using our piezoelectric printhead andthe relationship between the minimum driving voltage and the viscosity of the biomaterials was established. And the relationship between the satellite droplet and the slant jetting and the selection of the driving parameters and the regularity of the nozzle aperture profile during the jetting test were analyzed andsummarized. The effects of pulse amplitude, pulse width and pulse frequency on the droplet diameter and the droplet velocity were investigated by using thediaphragm piezoelectric printhead with 0.5% sodium alginate.The solidification mechanism of sodium alginate was analyzed, and the solidified state of the microdroplets was analyzed by experiment. The orthogonal experiment was carried out to evaluate the density of the microdroplets, and the optimum concentration was obtained. Qualitative analysis and give the printing model to reduce the extent of the collapse of the curing printing program. According to the orthogonal test conclusion and printing scheme, the 3D model of the biological model is printed with the tubular piezo nozzle, and the three-dimensional structure of the biological model with complete structure, accurate size and low collapse degree is obtained. The feasibility of the orthogonal test and the reliability of the bioprinting of the piezo printhead are verified.