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This paper presents a computer-controlled tilt-rotational UV-laser exposure system for 3D microfabrication. The system incorporates a beam expander to enlarge the beam width of a 405 nm laser diode, which serves as the light source. A computer-controlled sample holder platform utilizes two stepper motors to enable tilting and rotational movements, allowing the creation of complex microstructures using SU-8 photoresist via the lithography process. By implementing various combinations of tilting and rotation, arrays of intricate 3D microstructures, including pillars, angled pillars, horns, and bowties, were successfully fabricated, with feature heights ranging from 20 to 500 μm. The tiltable UV-laser exposure system holds significant potential for applications in 3D microelectromechanical systems (MEMS), such as micro-biosensors and micro-antennas for biomedical and RF applications. 

Microneedles are highly sought after for medicinal and cosmetic applications. However, the current manufacturing process for microneedles remains complicated, hindering its applicability to a broader variety of applications. As diffraction lithography has been recently reported as a simple method for fabricating solid microneedles, this paper presents the experimental validation of the use of ultraviolet light diffraction to control the liquid-to-solid transition of photosensitive resin to define the microneedle shape. The shapes of the resultant microneedles were investigated utilizing the primary experimental parameters including the photopattern size, ultraviolet light intensity, and the exposure time. Our fabrication results indicated that the fabricated microneedles became taller and larger in general when the experimental parameters were increased. Additionally, our investigation revealed four unique crosslinked resin morphologies during the first growth of the microneedle: microlens, first harmonic, first bell-tip, and second harmonic shapes. Additionally, by tilting the light exposure direction, a novel inclined microneedle array was fabricated for the first time. The fabricated microneedles were characterized with skin insertion and force-displacement tests. This experimental study enables the shapes and mechanical properties of the microneedles to be predicted in advance for mass production and wide practical use for biomedical or cosmetic applications.