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- ItemSteering Directional Light Emission and Mode Chirality through Postshaping of Cavity Geometry(Hoboke, NJ : Wiley, 2020) Wang, Jiawei; Tang, Min; Yang, Yue-De; Yin, Yin; Chen, Yan; Saggau, Christian Niclaas; Zhu, Minshen; Yuan, Xiaobo; Karnaushenko, Dmitriy; Huang, Yong-Zhen; Ma, Libo; Schmidt, Oliver G.Dielectric optical microcavities have been explored as an excellent platform to manipulate the light flow and investigate non‐Hermitian physics in open optical systems. For whispering gallery mode optical microcavities, modifying the rotational symmetry is highly desirable for intriguing phenomena such as degenerated chiral modes and directional light emission. However, for the state‐of‐the‐art approaches, namely deforming the cavity geometry by precision lithography or introducing local scatterers near the cavity boundary via micromanipulation, there is a lack of flexibility in fine‐adjusting of chiral symmetry and far‐field emission direction. Here, precise engineering of cavity boundary using electron‐beam‐induced deposition is reported based on rolled‐up nanomembrane‐enabled spiral‐shaped microcavities. The deformation of outer boundary results in delicate tailoring of asymmetric backscattering between the outer and inner rolling edges, and hence deterministically strong mode chirality. Besides, the crescent‐shaped high‐index nanocap leads to modified light tunneling channels and inflected far‐field emission angle. It is envisioned that such a localized deposition‐assisted technique for adjusting the structural deformation of 3D optical microcavities will be highly useful for understanding rich insights in non‐Hermitian photonics and unfolding exotic properties on lasing, sensing, and cavity quantum electrodynamics.
- ItemImperceptible magnetoelectronics(London : Nature Publishing Group, 2015) Melzer, Michael; Kaltenbrunner, Martin; Makarov, Denys; Karnaushenko, Dmitriy; Karnaushenko, Daniil; Sekitani, Tsuyoshi; Someya, Takao; Schmidt, Oliver G.Future electronic skin aims to mimic nature’s original both in functionality and appearance. Although some of the multifaceted properties of human skin may remain exclusive to the biological system, electronics opens a unique path that leads beyond imitation and could equip us with unfamiliar senses. Here we demonstrate giant magnetoresistive sensor foils with high sensitivity, unmatched flexibility and mechanical endurance. They are <2 μm thick, extremely flexible (bending radii <3 μm), lightweight (≈3 g m−2) and wearable as imperceptible magneto-sensitive skin that enables proximity detection, navigation and touchless control. On elastomeric supports, they can be stretched uniaxially or biaxially, reaching strains of >270% and endure over 1,000 cycles without fatigue. These ultrathin magnetic field sensors readily conform to ubiquitous objects including human skin and offer a new sense for soft robotics, safety and healthcare monitoring, consumer electronics and electronic skin devices.
- ItemShape-Controlled Flexible Microelectronics Facilitated by Integrated Sensors and Conductive Polymer Actuators(Weinheim : Wiley-VCH Verlag GmbH & Co. KGaA, 2021) Rivkin, Boris; Becker, Christian; Akbar, Farzin; Ravishankar, Rachappa; Karnaushenko, Dmitriy; Naumann, Ronald; Mirhajivarzaneh, Aaleh; Medina-Sánchez, Mariana; Karnaushenko, Daniil; Schmidt, Oliver G.The next generation of biomedical tools requires reshapeable electronics to closely interface with biological tissues. This will offer unique mechanical properties and the ability to conform to irregular geometries while being robust and lightweight. Such devices can be achieved with soft materials and thin-film structures that are able to reshape on demand. However, reshaping at the submillimeter scale remains a challenging task. Herein, shape-controlled microscale devices are demonstrated that integrate electronic sensors and electroactive polymer actuators. The fast and biocompatible actuators are capable of actively reshaping the device into flat or curved geometries. The curvature and position of the devices are monitored with strain or magnetic sensors. The sensor signals are used in a closed feedback loop to control the actuators. The devices are wafer-scale microfabricated resulting in multiple functional units capable of grasping, holding, and releasing biological tissues, as demonstrated with a neuronal bundle.