Software System Research Of Cryogenic Deposition-Based Multi-Nozzle 3D Bioprinting With Visual Measurement

3D bioprinting can be used to manufacture biological devices quickly and accurately.Recently,single-nozzle 3D bioprinting system has been gradually replaced by multi-nozzle 3D bioprinting system,to fulfill the clinical application demand for multi-component and complex structure of tissue engineering scaffolds.H owever,various processing parameters of multi-nozzle 3D bioprinting system are complex and require high coordination.For example,different nozzle setting value influences the scaffold formation effect directly.In addition,the measurement deficiency of formed fiber diameter could lead to a low yield,and a large amount of experiments are required for optimization design.Therefore,the development of multi-nozzle 3D bioprinting system with processing parameters measurement function has high practical value.Aiming to the self-developed cryogenic deposition multi-nozzle 3D bioprinting platform,a multi-nozzle 3D bioprinting software system with visual detection function was developed,and function test of the software was completed.Main contents are as follows:(1)The composition and structural characteristics of the multi-nozzle 3D bioprinting system's hardware were analyzed.Based on the combination of process characteristics of cryogenic deposition and the tissue engineering scaffolds forming demand,the requirements of software system were analyzed.The software system was divided into printing subsystem and processing parameters detection subsystem;thus,the overall design of software system was completed.(2)The design and realization of printing subsystem was completed.Printing function,which is the core function of 3D printing system,was divided into two functional modules: "slicing and path planning" and "hardware interaction".The two function modules were programmed using C++ language.In slicing and path planning function module,a composite path planning algorithm was designed and implemented.Suitable printing path can be planned based on the input model data.In hardware interaction function module,hardware system control program which can drive the printing platform was written,implementing the printing function based on the planned path data.(3)A camera was installed on the original 3D bioprinting platform.The processing parameters detection subsystem was designed and accomplished based on the machine vision.This subsystem was used to obtain two kinds of processing parameters which is used to assist to optimize process parameters including the nozzle setting value and the formed fiber diameter.The original images of nozzles and formed fibers were obtained separately based on Open CV.And then,the image processing which has gray level transformation,filtering denoising,edge detection and other steps was realized.Feature data was extracted from the image processing result.Finally,two processing parameters were calculated based on the feature extraction result.(4)The interface system of the software was designed and accomplished based on Qt and Qt Creator.The display function module was realized based on Open GL.This module can be used to display the model input by users and nozzle motion path data,thereby giving users visual feedback.(5)Through a series of experiments,the functions of each parts of the software system were tested to evaluate the functionality,practicability and stability.1)The printing experiments of single-nozzle simple scaffold and single-nozzle complex-contour scaffold were carried out.The results showed that the software system can plan the path suitable for printing according to the input model.The software system supports the user to set and modify the print path autonomously,which is highly customizable.The software system can control the hardware to run stably,which means the printing function is effective.2)The experiment of measuring the formed fiber diameter was carried out,and the function results were proved to be accurate.3)The multi-nozzle formation synthesis experiment was completed,and all module functions of the software system was applied to prepare the multi-component scaffolds.The results proved the accuracy of the nozzle setting value measurement function and the practicability of the processing parameters detection function.In addition,it also proved that the system possesses the ability to prepare tissue engineering scaffolds with multi-component and complex structure.