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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. 

Continuous post-endovascular aneurysm repair (EVAR) surveillance is critical for patients who have undergone a stenting procedure. Despite its life-saving importance, studies have reported that patients gradually discontinue post-EVAR surveillance due to the significant burden associated with CT scans, X-rays, etc. Considering the importance and necessity of post-EVAR surveillance, we introduce a self-resonating flexible tube implanted in a standard clinically approved stent that enables wireless sensing of blood pressure inside an aneurysm through inductive coupling. To enable blood pressure monitoring outside the body, we designed and fabricated a spiral-type antenna, specifically crafted to capture the inherent resonance frequency of the self-resonating stent tube. To showcase the wireless pressure monitoring capability, a 3D-printed elastic model of an abdominal aortic aneurysm (AAA) was prepared. Our quantitative study validated the pressure-sensing capability with adequate sensitivity (up to 687.5 Hz/mmHg) when tissue was located between the stent and the external antenna. The wireless sensing also presents a consistent linear shift in resonance frequency across all tested measuring distances as the applied pressure ranges from 60 to 140 mmHg. The proposed self-resonating stent offers promising insights for improving post-EVAR surveillance. 

Hollow microneedles are extremely attractive to drug delivery domains with high demands from clinics and industry. However, its complicated fabrication processes have impeded its wide adoption. This paper presents a simple one-step fabrication method for hollow microneedles based on diffraction UV lithography and solid-liquid light propagation. The fabrication process utilizes bottom-up exposure of a liquid photosensitive resin through photomask patterns comprising a plurality of apertures. Hollow microneedles with various heights were fabricated in a range of 400 µm to 600 µm from a few minutes of UV exposure. The fabricated hollow microneedles were characterized with force-displacement tests showing a good tip strength of 0.35 N per single unit. A hollow fluidic test on a pig cadaver skin showed great potential for drug delivery. Also, batch fabrication with multiple height microneedles on a single substrate has demonstrated compatibility with the manufacturing process.