Highly uniform and controllable micropatterning of a hydrogel on microcantilevers

This paper reports a novel method for highly controllable local patterning of a hydrogel on microcantilevers. We constructed a dynamic mask lithography setup based on a commercial beam projector and a 3-axis microstage. Dynamic masks generated from the beam projector controlled the shape, size, and position of hydrogel patterns while the 3-axis microstage mainly controlled the thickness of hydrogel patterns. Using the constructed setup, polyethyleneglycol diacrylate (PEGDA) was patterned on microfabricated cantilevers in a highly controlled manner. Currently, the smallest PEGDA patternable is a 5-μm-diameter circle with a thickness of ～10 μm. To confirm thicknesses of patterned PEGDAs, resonance frequencies of microcantilevers were measured before and after each PEGDA patterning. Thicknesses extracted from resonance measurements showed good agreement with measurements using an optical microscope.