Additive manufacturing may be used in the applications of IC chips, medicare, and functional materials. However, the existing 3D printing technology is still hard to meet the requirements of printing accuracy (micro-scale resolution) and device format (in the scale of cm). Because of the failure in printing resolution and printing scale, 3D printer still fails to effectively solve the problems in the field of biological applications.

 

Figure 1 shows the printing of a carrier holder for printing in the field of tissue engineering. 3D printing technology provides new possibilities for biological scientific research and medical diagnostic methods. However, the application of 3D printing technology in the biological field is also faced with many limitations, mainly because the printing precision and format cannot meet the application requirements.

Figure 1 shows the printing of a carrier holder for printing in the field of tissue engineering. 3D printing technology provides new possibilities for biological scientific research and medical diagnostic methods. However, the application of 3D printing technology in the biological field is also faced with many limitations, mainly because the printing precision and format cannot meet the application requirements.

On one hand, the additive manufacturing based on two-photon lithography enables 3D printing with feature size down to 0.1 μm. However, because of the serial printing mode, it is extremely inefficient and small in size (hundreds of micrometers), which cannot meet the requirements of the development of high-precision biological chips. On the other hand, the lateral resolution of projection based UV lithography is limited to around 60 microns, influenced by the immersion printing mode, the resolution of the optical projection system and data processing^[1]. Therefore, the 3D printing technology with micron scale resolution has been an unsolved problem despite the great demand in market.

With long-term technical accumulation in large scale direct laser writing system, big data processing, and development of R2R nano-imprinting technology, SVG R&D team integrate the optical system in the micro lithography technology to the 3D printing technology. As a result, the lateral printing precision of 3D printing system is improved by an order of magnitude.

In the previous 3D curing (SLA) 3D printers, all the printed objects are immersed in a groove, and the vertical printing accuracy is determined by the focusing depth of the laser spot (see figure 2, reference 1). Both The lateral and vertical printing resolution is low. The team developed a new printing mode, i.e. "coating - exposure - separation" method, to achieve higher vertical (layered) printing accuracy. The self-developed 3D printer coat and print the structures layer-by-layer, significantly improved the vertical printing accuracy of 3D objects. The team solves the problem that the process of subsequent printing layer has great influence on the existing printing layer. Therefore, the self-developed "multi-μ 3d Printer " can print micro 3D structures with extremely high precision.

Fig.2  Schematic diagram of traditional SLA 3D printing mode

The lateral resolution (characteristics of the structure) is 5μm-25μm(projection resolution 1 micron) and the vertical accuracy(layer thickness) is 2μm-20μm. The photos of printed structures are shown in figure 3 below:

Transverse structure test: cone-shaped top 5 microns, bottom 50 microns, height 150 microns

Layer thickness test: minimum layer thickness 2 microns

Hollow column test: wall 25 microns, high 180 microns. The side wall is smooth and clear

Open hole test of hollow column: the side length of the hole is 50 microns; Gradient 3D printed sample (right) SEM photo

Fig. 3  Micro nano 3D printed test sample

 

Combined with nano imprinting/embossing technology, the multi-3d Printer is expected to play an important role in the areas of biological chips, sensors and MEMS devices.

Fig. 4 high-precision micro-nano 3D printing system: multi-μ 3d Printer photo

For example, bio assays used for cell detection (Fig.5) cannot be realized by other methods because of the high aspect ratio.

Fig. 5 schematic diagram of biochip structure

References:

1. 3D printed microfluidic devices: enablers and barriers,http://pubs.rsc.org/en/content/articlehtml/2016/lc/c6lc00284f

2. T. Billiet, M. Vandenhaute, J. Schelfhout, S. Van Vlierberghe and P. Dubruel, Biomaterials, 2012,33, 6020–6041