Manufacturing Microlens Array (MLAs) by Using Micromachining and Expandable Elastomer
Pin-Chuan Chen, Member, IEEE
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
pcchen@mail.ntust.edu.tw
Abstract
Microlens arrays (MLAs) nowadays are critical micro-optical components and it can be applied in many application fields, such as optical communication systems and flat panel display modules. This article describes a novel approach to the fabrication of tunable polydimethylsiloxane (PDMS) MLAs. A polydimethylsiloxane (PDMS) membrane is bonded to a micro-milled poly(methyl methacrylate) (PMMA) microfluidic chip and exposed to silicone oil of a specific viscosity. Molecules in the oil insert themselves into the molecular structure of the PDMS membrane, causing it to swell and subsequently form dome-shaped MLAs. From our experiments, we derived the following conclusions: (1) The homogeneous swelling of the PDMS resulted in MLAs with a high numerical aperture (0.5), high uniformity lighting, clear imaging, and high stability; (2) The shorter molecular chains in low-viscosity oils diffused more readily into the PDMS membrane, which increased the effects on swelling, resulting in MLAs with higher sag height and higher numerical aperture. For example, the 5cst silicone oil resulted in sag height of 191μm with NA of 0.50, whereas, the 100cst silicone oil resulted in sag height of 86μm with numerical aperture of 0.33; (3) The integrated mixer module enabled the simultaneous tuning of the 7×7 MLAs simply by adjusting the injection flow rates of the constituent silicone oils.
Short Bio
Pin-Chuan Chen is a Director of Mini/Micro/Manufacturing Lab and a Professor of Mechanical Engineering Department at the National Taiwan University of Science and Technology (Taiwan Tech), Taipei, Taiwan. He received his Ph.D. in 2009 from Mechanical Engineering Department of Louisiana State University, Baton Rouge, Louisiana, USA. After graduation, Dr. Chen worked for two years as a Researcher in the Microfluidics Manufacturing Programme of the Singapore Institute of Manufacturing Technology (SIMTech, Singapore) before joining Taiwan Tech as an Assistant Professor in 2011. He was admitted as a fellow of The Royal Society of Chemistry (FRSC) in February 2020. His current research interests focus on building lifelike biomodels via novel fabrication processes, using additive manufacturing (3D printing) to create micro/mill fluidic devices for chemical/biochemical applications (new psychoactive substances (NPS), cell response to drugs), manufacturing of polymer/paper microfluidics for chemical/biochemical applications, novel bonding method for homogeneous/heterogeneous substrates for creating microfluidic devices.