﻿parameter acquisition for dlp printing

Quantitative Characterization of Bioink Properties for Continuous DLP Printing

Tissue engineering1 is important in the field of organ repair. Due to the lack of organ donation, some diseases, such as liver failure and kidney failure, cannot be cured well, and many patients do not receive timely treatment2. Organoids with the required function of the organs may solve the problem caused by the lack of organ donation. The construction of organoids depends on the progress and development of bioprinting technology3.
Compared with extrusion-type bioprinting4 and inkjet-type bioprinting5, the printing speed and printing accuracy of the digital light processing (DLP) bioprinting method are higher6,7. The printing module of the extrusion-type method is line-by-line, while the printing module of the inkjet-type method is dot-by-dot, which is less efficient than the layer-by-layer printing module of DLP bioprinting. The modulated ultraviolet (UV) light exposure to a whole layer of material to cure a layer in DLP bioprinting and the feature size of the image determines the accuracy of DLP printing. This makes DLP technology very efficient8,9,10. Due to overcuring of the UV light, the precise relationship between the curing time and the printing size is important for high-accuracy DLP bioprinting. Furthermore, continuous DLP printing is a modification of DLP printing method that can greatly improve the printing efficiency11,12,13. For continuous DLP printing, precise printing conditions are the most important factors.
The relationship between the curing time and the printing size is called the Jacobs working curve, which is widely used in DLP printing14,15,16. The traditional method to obtain the relationship is to expose the material for a certain time and measure the curing thickness to obtain a data point about the exposure time and curing thickness. Repeating this operation at least five times and fitting the data points obtains the Jacobs working curve. However, this method has obvious disadvantages; it needs to consume a lot of material to achieve the curing, the results are highly dependent on the printing conditions, the bioinks used in DLP bioprinting are expensive and rare, and the formability of the bioinks is usually not good, which can lead to inaccurate measurements of curing thickness.
This article provides a new method to obtain the curing relationship according to the physical properties of the bioink. Using this theory can optimize continuous DLP printing. This method can be used to obtain the curing relationship more quickly and accurately; the continuous DLP curing can therefore be better determined.

Author Spotlight: Quantitative Characterization of Liquid Photosensitive Bioink Properties for Continuous Digital Light Processing Based Printing  

Quantitative Characterization of Liquid Photosensitive Bioink Properties for Continuous Digital Light Processing Based Printing

My research mainly involves DLP 3D bio printing and tissue engineering. We try to optimize and improve the DLP printing process and formula theory, so that the printed tissue engineering scaffold can better meet the actual clinic application needs. The printing conditions of the existing light curable materials rely on manual experiments and are obtained by feeding the data of multiple performing experiments.Such experiments waste material and reduced printing efficiency. I constructed a theoretical working curve and determined the DLP printing pyramids only based on the physical properties of the material. Dynamics both best concept is proposed to be applied in DLP printing to realize DLP format of complex dimensional structures of extremely soft materials.This method can improve the efficiency of determining the printing conditions of photo curable materials. This technology can provide technical support for the research and development of photo curable materials and the accurate printing of these materials.

Watch this Scientific Journal Video about ﻿Parameter Acquisition for DLP Printing at JoVE.com

Parameter Acquisition for DLP Printing  

﻿Parameter Acquisition for DLP Printing

Begin by measuring the threshold time of the bio-ink using a rheometer with a temperature control element. Utilize a 365 nanometer light source to expose the testing platform of the rheometer and set the light intensity to a certain value. In the rheometer software, go to the time settings option and set the rheometer to acquire the time moduli data for 300 data points with each data point taken every 0.3 seconds.Click the start test button on the rheometer software to begin the test. Simultaneously, click the start button of the light source. To calculate the threshold time, record the corresponding time counting from the start of exposure when the storage modulus data is equal to the loss modulus data.Then build the absorbance test equipment by using upper and lower glass slides and the ring-shaped printed structure. Clamp the ring between the glass slides so that the inner circle of the ring forms the chamber. Place the chamber on the test area of the light intensity meter and set the light source to expose the chamber area.When the test chamber is not filled with material from the absorbance test equipment, measure the incident light intensity, II, by reading the display of the light intensity meter. Next, fill the test chamber with 10 microliters of bio-ink. Expose the test chamber containing bio-ink to ultraviolet light at 365 nanometers.Obtain the light intensity, IIH, by reading the display. When the value no longer changes on the light intensity meter, read the display to obtain the light intensity when the bio-ink is cured. The value is the solid absorbance, ISH.

Research

JoVE Journal

Bioengineering

Precise printing fabrication of bioinks is a prerequisite for tissue engineering; the Jacobs working curve is the tool to determine the precise printing ...