Adaptive Elastomer-liquid Lenses for Advancing the Imaging Capability of Miniaturized Optical Systems Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Hanyang Huang Graduate Program in Biomedical Engineering The Ohio State University 2019 Dissertation Committee Professor Yi Zhao, Advisor Professor Jun Liu Professor Derek Hansford 1 Copyrighted by Hanyang Huang 2019 2 Abstract Advanced imaging capabilities, such as macro/microscopic imaging, wide-angle imaging, optical zooming, stereoscopic imaging, adaptive focusing and depth perception, are often preferable in optical imaging systems. In conventional optical imaging systems, these functions are typically implemented through replacement and/or precise displacement of multiple solid optical elements. This may complicate the optical system configuration and increase the overall system dimension and cost. New adaptive optics approaches that can incorporate advanced imaging capabilities in miniaturized optical systems are thus of imperative needs. Optofluidic elastomer-liquid lenses which are constructed by encapsulating an optical fluid within a deformable cavity made of solid materials have attracted considerable attention in the recent past. Like the human eye lens, elastomer-liquid lenses have a deformable shape by adjusting the fluid pressure, allowing for fast focusing the objects of interest. They provide a new route for designing and improving miniature and adaptive imaging devices by courtesy of their compact size and tunable optical powers. However, the low image resolution due to optical aberrations remains as a primary limitation of optofluidic lenses. There are few studies providing a practical approach to compensating optical aberrations without compromising the miniaturization and the range of adaptive refractive power. ii The gist of this dissertation is to introduce novel miniaturized optical systems with advanced imaging capabilities, enabled by adaptive elastomer-liquid lenses with improved resolutions. First, different optical resolution improvement mechanisms for elastomer- liquid lenses are introduced, including using an optimized inhomogeneous lens membrane, using a meniscus lens configuration and using a biconvex lens configuration. Results show that all three approaches are effective in improving the optical resolutions of elastomer- liquid lenses at high diopters. Secondly, an adaptive smartphone-based scanning microscope using two elastomer-liquid lenses with aforementioned designs is developed. Its capability of achieving tunable magnifications and optical scanning is demonstrated. Thirdly, a reconfigurable miniature optofluidic device that allows for adaptive imaging and positioning with a wide FOV using a planar image sensor is proposed. Fourthly, a smartphone-based whole slide imaging device with tunable magnifications and high resolutions using two elastomer-liquid lenses with optimized inhomogeneous membranes is introduced. Finally, a composite optofluidic zoom lens component that integrates a plano-convex liquid lens and a plano-concave liquid lens is proposed. The two lenses are inter-connected and actuated by a single pneumatic actuation unit, which largely reduces the complexity of the control unit and the overall size of the imaging system. This study provides a powerful solution to overcome the bottleneck of optical resolution limitations of elastomer-liquid lenses and is expected to foster new advanced imaging capabilities where miniaturization and low cost is at a premium. iii Dedication This dissertation is dedicated to my loving and supportive wife, Na Pan, my cute and smart daughter, Hannah Ziyu Huang, my brilliant and considerate baby boy, Nathan Zicheng Huang, and my always encouraging, ever thoughtful parents, Dehuai Huang and Xiuzhen Bian. iv Acknowledgments I would like to thank all the people who provided me with guidance, confidence, and assistance throughout the Ph.D. program. Without you, I would never be able to get so far. This research was performed under the guidance of my advisor, Professor Yi Zhao, to whom I would like to express my sincere gratitude, for his consistent encouragement, inspiration, and academic support. Without his insightful and profound advice, I would never be able to follow the right direction and overcome the obstacles during my study. I am thankful to my former and current labmates, Dr. Kang Wei, Dr. Xu Zhang, Dr. Qian Wang, Dr. Lin Qi, Ye Niu, Yu Zhang, and Jacob Kresslein for their kind help in my work and life. In addition, I would like to thank Professor Jun Liu and Professor Derek Hansford for their continuing service on both my candidacy and dissertation committee. Finally, I would like to express my sincerest appreciation to my wife, Na Pan, who was always there cheering me up and stood by me throughout my good and bad times. v Vita 2007-2011 B.S. Mechanical Engineering, University of Science and Technology of China 2011-2014 M.S. Mechanical Engineering, Chinese Academy of Sciences 2014-2017 Graduate Research Associate, Biomedical Engineering, The Ohio State University 2017-present Pelotonia Fellow, Wexner Medical Center, The Ohio State University Publications Journal Articles Hanyang Huang, and Yi Zhao. Optofluidic Lenses for 2D and 3D imaging. Journal of Micromechanics and Microengineering, 29 (7), 073001, 2019. Kang Wei, Hanyang Huang, Qian Wang, and Yi Zhao. Focus-tunable liquid lens with an aspherical membrane for improved central and peripheral resolutions at high diopters. Optics Express, 24(4): 3929-3939, 2016. Qian Wang, Hanyang Huang, Kang Wei, and Yi Zhao. Time-dependent combinatory effects of active mechanical loading and passive topographical cues on cell orientation. Biotechnology and bioengineering 113, 2191-2201, 2016. Qian Wang, Hanyang Huang, Ye Niu, Xu Zhang, Pengfei Jiang, Katelyn E Swindle- Reilly, and Yi Zhao. Microscale cell stretcher to generate spatially uniform equi-biaxial strain using an elastomeric membrane with a contoured thickness profile. Sensors and Actuators B: Chemical 273, 1600-1609, 2018. vi Fangsheng Huang, Ye Niu, Zhiqiang Zhu, Hanyang Huang, Yue Xue, Ting Si, Ronald X. Xu and Yi Zhao. Oblique interface shearing (OIS): single-step microdroplet generation and on-demand positioning. Soft Matter 15, 4782-4786, 2019. Hanyang Huang, Kang Wei, and Yi Zhao. Optomechanical optimization of the inhomogeneous membrane for tunable elastomer liquid lenses with low spherical aberration. Optics Letters, Submitted. Hanyang Huang, and Yi Zhao. Adaptive elastomer-liquid meniscus lens with reduced spherical aberration. Optics Letters, Submitted. Conference Proceedings (Full paper) Hanyang Huang and Yi Zhao. A reconfigurable optofluidic device for adaptive imaging and position estimation with a wide field of view. Solid-State Sensors, Actuators and Microsystems Workshop Hilton Head Island, South Carolina: 19-22, 2018. Hanyang Huang and Yi Zhao. Smartphone based focus-free macroscopy using an adaptive droplet lens. Solid-State Sensors, Actuators and Microsystems Workshop Hilton Head Island, South Carolina: 334-337, 2018. Hanyang Huang, Kang Wei, and Yi Zhao. Variable focus smartphone-based microscope using an elastomer liquid lens. Proceeding of the 29th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2016), Shanghai, China: 808-811. Hanyang Huang, Kang Wei, and Yi Zhao. A compound optofluidic lens system for switchable 2D/3D imaging. Proceeding of the 29th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2016), Shanghai, China: 2-5. Hanyang Huang, Kang Wei, and Yi Zhao. Improved optical resolution for elastomer- liquid lens at high diopter using varied thickness membrane. Biomedical Optics Conference, 2016 SPIE Photonics West, San Francisco, CA: 9705-3. Hanyang Huang, Kang Wei, and Yi Zhao. Adaptive optofluidic lenses for switchable 2D and 3D endoscope. Biomedical Optics Conference, 2016 SPIE Photonics West, San Francisco, CA: 9705-25. Fields of Study Major Field: Biomedical Engineering vii Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments............................................................................................................... v Vita ..................................................................................................................................... vi Table of Contents ............................................................................................................. viii List of Tables .................................................................................................................... xii List of Figures .................................................................................................................. xiii Chapter 1 Background ........................................................................................................ 1 1.1 Overview of Optofluidic Lenses ............................................................................... 1 1.2 Configuration and Actuation..................................................................................... 4 1.2.1 Type I: lenses with tunable fluid/fluid interface(s) ............................................ 4 1.2.1.1 Lenses