Digital Fabrication of 3D Bio Devices Utilizing PELID (Pattern- ing with Electrostatically-Injected Droplet) Method

In this paper, we fabricated soft 3D bio devices utilizing PELID (Patterning with Electrostatically-Injected Droplet) method. It is preferable to perform laboratory experiments with 3D structures in bioengineering. We have investigated mechanism and fundamental characteristics of the PELID method and now been applying for new printing technology of high image quality and 3D printing technology. The method has two merits, higher resolution than commercial printer and ability to eject with highly viscous liquid. We can eject viscous paste that viscosity is 30000 mPas. At DF 2010, I already presented that cells and scaffolds were printed to fabricate 3D cell structures because scaffolds assisted the weight of cells. Now, we should fabricate 3D structure that has cave because real 3D structure has blood vessel like cave. It is difficult to fabricate 3D structure that has cave. Gelatin is used as sacrificial layer. When the printed 3D structure is put into hot water, gelatin is removed. With this technique, we can print 3D structure that has cave. The tube filled with the liquid that contained gelatin and the tube filled with the liquid that contained calcium alginate was hanged down perpendicular to a dish. Voltage was applied between the syringes and the dish by power supplies (voltage range: -5kV ~ +5kV, Matsusada Precision Inc, Tokyo, HVR10P). The air gap was adjusted by a z-stage and the plate electrode was moved in x and y directions with two linear motors. PC controlled voltage application and motion of linear stages. We fabricated 3D bio devices. Introduction The goal of this study is to fabricate precision 3-Dimensional cell structures utilizing PELID (Patterning with ELectrostaticallyInjected Droplet) method. It is preferable to perform laboratory experiments with 3D cell structures in tissue engineering and artificial organ. However it is difficult to fabricate 3D cell structures because own weight of cell is above the bonding force between cells. Many researchers carried out studies on Bio-print. 3D positioning of calcium alginate that contained living cells utilizing commercial inkjet was succeed [1, 2]. The papers described that calcium alginate was used as scaffolds. Calcium alginate is useful to fabricate 3 Dimensional structures because the stiffness is relatively high. We applied the PELID method for patterning living cells and scaffolds to fabricate 3D cell structures [3, 4]. Our inkjet technology, PELID method, has two merits; those are high resolution and ability to eject highly viscous liquid. These merits are suitable to print cells precisely and eject highly viscous scaffolds. Bone stem cells [3] and MDCK cells [4] were printed utilizing the PELID method. We utilize collagen and/or gelatin as scaffolds to fabricate 3D cell structures because collagen and gelatin are most often-used scaffolds in vivo. However, the height of the fabricated 3D structures was low because the stiffness was low in case that collagen and gelatin was used as scaffolds. To clear this problem, we plan to print calcium alginate that supports collagen. In this paper, we investigate fundamental characteristics to print calcium alginate and optimize the print condition to fabricate high 3D cell structures. Experimental Set-up An experimental set-up shown in Fig.1 is constructed to investigate characteristics to print calcium alginate utilizing the PELID method. Figure 1 (b) shows the enlarged view around the nozzle. Calcium alginate is produced when high voltage is applied between nozzle that is filled with aqueous solution of sodium alginate and target that is slightly filled with aqueous solution of calcium chloride. The nozzle is hanged down perpendicular to the target. Voltage is applied between the nozzle and the target by a power supply (voltage range: -5kV ~ +5kV, Matsusada Precision Inc, Tokyo, HVR-10P). The air gap is adjusted by a z-stage and the dish is moved in x and y directions with two linear motors. A PC controls voltage application and motion of the linear stages. When the printed 3D structure is high, the electric field around the tip of the nozzle is relatively weak because the air gap between