This paper presents a chip containing a flexible scaffold which facilitates the construction of tissues with different shapes. The chip, entirely made of Polydimethylsiloxane (PDMS), has 2 main components including actuator and channel layers. The actuator layer consists of a 6×6 array of membrane actuators, with round shapes. The channel layer has a single layered structure due to the simplicity in chip assembly and the ability to observe seeded cells via a microscope. The actuator array offers a flat surface, like a normal cell culture dish, in the rest state, while it temporarily offers a scaffold structure when actuators are activated. By changing the actuation pattern, formation of many scaffold structures is possible. To demonstrate the utility of this chip in biological application, a syringe pump is connected to all actuators to produced 2 different scaffolds, enabling the fabrication of multiple flat round and lattice shaped tissues. NIH3T3 cells with the amount of 5×106were seeded on the scaffold and kept inside the incubator for 24 hours. The 25 round shaped tissues with an average diameter of 623.87 μm were simultaneously fabricated when a scaffold with large deformed actuators was used. The lattice shaped tissue with a line width of about 300 μm was also fabricated with a different scaffold structure which has less actuator displacement. Results suggest the potential usage of this chip for the preparation of many building units with different structures, without the necessity of making a new mold for a new tissue shape.

This study proposed a method for the fine alignment of polydimethylsiloxane (PDMS) stamp used in multiple microcontact printing. The procedure of alignment method was organized into three steps; (1) the fabrication of PDMS stamp with an alignment marker, (2) the position detection of PDMS stamp with a noncontact laser displacement sensor on an automated planar x-y axes stage, and (3) the position adjustment of PDMS stamp to target position with another automated planar x-y-θ axes stage. The procedure was able to perform without contact onto the surface of PDMS stamp just before the moment of contact printing. Therefore, the surface would be safe from molecular/bacterial contamination. This study implemented the procedure into a developed system for the alignment of PDMS stamp. After adjusting the position of PDMS stamps applied with fibronectin-binding-fluorescent dyes with three different colors, contact printing was performed. As a result, the error of position between two different patterns of fibronectin was within 33 μm. This method would be useful for generating a multi-type-cellular tissue in tissue engineering and regenerative medicine.

Micro contact printing is a quite useful technique for patterning protein such as cellular adhesion molecular. Especially, the method is popular to fabricate substrates for cell patterning in tissue engineering. However, a manual printing is difficult, because the stamp made from polydimethylsiloxane (PDMS) is easily deformed, and a printed pattern is also crushed. This study focused on the stiffness of PDMS stamp and discussed a micro-contact-printing controlled stamping force for a higher quality of pattern than that of manual. Considering in availability in medical or biological laboratory, the measurement method of stamp stiffness was developed by using a general microscope. The proposed stamping method gave a high printing-quality with 2.5% error of stamping area. Stamping setup controlling stamping force was developed, and a protein was patterned on a cell-culture substrate by the setup. By using the protein-patterned substrate, two-cell-patterned co-culture was successfully performed.

In this study, we present a new fixture (self-attachable fixture) and tensile test system for measuring mechanical properties of cell sheet. To evaluate strength of cell sheet, it is the most important to measure mechanical properties of tensile mode. However, there has been no study which measured the tensile mechanical properties of cell sheet, since it has been difficult to attach a cell sheet in the tensile test system owing to the structure of the conventional fixture, and there has been no tensile test system which had a measurement range that covered the tension force range of the cell sheets. Therefore, we have addressed these problems by developing a self-attachable fixture and a tensile test system. By using developed system, we measured mechanical properties (tension, stress and initial stiffness) C2C12 of cell sheet cultured in different recipe of culture medium. The initial stiffness of cell sheet cultured in culture medium without FBS had a tendency to become stiffer. This indicates that our new fixture and test system are applicable for evaluating mechanical properties of cell sheets.