on the printing area of the printer, different designs can be chosen

(see Note 7). The fabrication methods were summarized in Fig. 1c.

3.2

Direct

Fabrication

1. The detail of the direct fabrication method was described

in [13].

2. Remove the printed spiral chip carefully from the pick-up

platform with scalpel.

3. Wash the chip with IPA and dried with an air nozzle or hair-

dryer. Repeat the washing process for at least three times until

there is no visible uncured resin.

4. Following washing, cure the spiral chip in the UV curing

chamber for 2 min to further solidify the resin.

5. Tape the chip with Scotch tape to remove potentially available

dust (see Note 8).

6. Bind the chip on PMMA-base with double-sided adhesive tape.

7. Press the chip and substrate together with force, make sure the

chips are well attached to the substrate (see Note 9).

8. Place the silicone tubing inside the inlet (see Note 10) and

outlets (see Note 11) of the spiral chip.

3.3

Mold Fabrication

1. The detail of the mold fabrication method was described

in [14].

2. Remove the printed spiral mold from the pick-up platform by

scalpel.

3. Wash carefully with IPA and dried with an air nozzle or hair-

dryer. Repeat the washing process for at least three times until

there is no visible uncured resin.

4. Cure the spiral mold in the UV curing chamber for 2 min to

further solidify the resin.

5. Dip the mold in the IPA for at least 6 h to clean up the surface

of the mold.

6. Put the spiral mold in the plasma machine, vacuum for 4 min,

and plasma treat for 2 min.

7. After plasma treatment, Place the treated mold immediately in

vacuum chamber. Add 100 μL of Trichloro (1H, 1H, 2H,

2H-perfluoro-octyl) silane in a small container inside the vac-

uum chamber, vacuum for 2 min and leave the mold inside for

at least 8 h. These treatments allow a layer of silane to coat on

the surface of the mold, helping PDMS device to be peeled off

from the mold easier.

8. Prepare complete PDMS mixture by mixing the PDMS

reagents and curing agent at 10:1 ratio, mix thoroughly for

5 min (see Note 12). Degas the PDMS in a vacuum pot until

there is no bubble left.

Bioreactor-Based Adherent Cells Harvesting from Microcarriers with 3D. . .

261