2.1. Photomask Fabrication

Photomasks were created using two different printing methods. The first method involves using a 2400 dpi laser printer (Canon LBP3300, Tokyo, Japan) onto a transparent film (Polyethylene terephthalate (PET) A4 transparent sheet), which is commonly used for printed circuit board fabrication. To improve the contrast and homogeneity of the printed pattern, a toner aided spray (Toner Aide Enhancer, Sprayway^®, Addison, IL, USA) was used by spraying the pattern at a distance of 15 to 20 cm and dried for 5 min, according to the manufacturer’s instructions. This spray dissolves the toner, which enables merging of neighboring ink spots and filling open spaces. This results in darker patterns. The second method involves a widely used printing called offset printing from a printing provider (Saigon 3 Printing Co., Ltd., Ho Chi Minh City, Vietnam).