DSpace :: Browsing by Author "Schmidt, Oliver G."

Browsing by Author "Schmidt, Oliver G."

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3D Self‐Assembled Microelectronic Devices: Concepts, Materials, Applications
(Hoboke, NJ : Wiley, 2020) Karnaushenko, Daniil; Kang, Tong; Bandari, Vineeth K.; Zhu, Feng; Schmidt, Oliver G.
Modern microelectronic systems and their components are essentially 3D devices that have become smaller and lighter in order to improve performance and reduce costs. To maintain this trend, novel materials and technologies are required that provide more structural freedom in 3D over conventional microelectronics, as well as easier parallel fabrication routes while maintaining compatability with existing manufacturing methods. Self‐assembly of initially planar membranes into complex 3D architectures offers a wealth of opportunities to accommodate thin‐film microelectronic functionalities in devices and systems possessing improved performance and higher integration density. Existing work in this field, with a focus on components constructed from 3D self‐assembly, is reviewed, and an outlook on their application potential in tomorrow's microelectronics world is provided.
A Rotating Spiral Micromotor for Noninvasive Zygote Transfer
(Hoboke, NJ : Wiley, 2020) Schwarz, Lukas; Karnaushenko, Dmitriy D.; Hebenstreit, Franziska; Naumann, Ronald; Schmidt, Oliver G.; Medina-Sánchez, Mariana
Embryo transfer (ET) is a decisive step in the in vitro fertilization process. In most cases, the embryo is transferred to the uterus after several days of in vitro culture. Although studies have identified the beneficial effects of ET on proper embryo development in the earlier stages, this strategy is compromised by the necessity to transfer early embryos (zygotes) back to the fallopian tube instead of the uterus, which requires a more invasive, laparoscopic procedure, termed zygote intrafallopian transfer (ZIFT). Magnetic micromotors offer the possibility to mitigate such surgical interventions, as they have the potential to transport and deliver cellular cargo such as zygotes through the uterus and fallopian tube noninvasively, actuated by an externally applied rotating magnetic field. This study presents the capture, transport, and release of bovine and murine zygotes using two types of magnetic micropropellers, helix and spiral. Although helices represent an established micromotor architecture, spirals surpass them in terms of motion performance and with their ability to reliably capture and secure the cargo during both motion and transfer between different environments. Herein, this is demonstrated with murine oocytes/zygotes as the cargo; this is the first step toward the application of noninvasive, magnetic micromotor‐assisted ZIFT.
Active Matrix Flexible Sensory Systems: Materials, Design, Fabrication, and Integration
(Weinheim : Wiley-VCH Verlag GmbH & Co. KGaA, 2022) Bao, Bin; Karnaushenko, Dmitriy D.; Schmidt, Oliver G.; Song, Yanlin; Karnaushenko, Daniil
A variety of modern applications including soft robotics, prosthetics, and health monitoring devices that cover electronic skins (e-skins), wearables as well as implants have been developed within the last two decades to bridge the gap between artificial and biological systems. During this development, high-density integration of various sensing modalities into flexible electronic devices becomes vitally important to improve the perception and interaction of the human bodies and robotic appliances with external environment. As a key component in flexible electronics, the flexible thin-film transistors (TFTs) have seen significant advances, allowing for building flexible active matrices. The flexible active matrices have been integrated with distributed arrays of sensing elements, enabling the detection of signals over a large area. The integration of sensors within pixels of flexible active matrices has brought the application scenarios to a higher level of sophistication with many advanced functionalities. Herein, recent progress in the active matrix flexible sensory systems is reviewed. The materials used to construct the semiconductor channels, the dielectric layers, and the flexible substrates for the active matrices are summarized. The pixel designs and fabrication strategies for the active matrix flexible sensory systems are briefly discussed. The applications of the flexible sensory systems are exemplified by reviewing pressure sensors, temperature sensors, photodetectors, magnetic sensors, and biosignal sensors. At the end, the recent development is summarized and the vision on the further advances of flexible active matrix sensory systems is provided.
Advanced architecture designs towards high-performance 3D microbatteries
(Amsterdam : Elsevier, 2021) Li, Yang; Qu, Jiang; Li, Fei; Qu, Zhe; Tang, Hongmei; Liu, Lixiang; Zhu, Minshen; Schmidt, Oliver G.
Rechargeable microbatteries are important power supplies for microelectronic devices. Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas. In addition to the development of new high-performance electrode materials, the device configurations of microbatteries also play an important role in enhancing the output energy and miniaturizing the footprint area. To make a clear vision on the design principle of rechargeable microbatteries, we firstly summarize the typical configurations of microbatteries. The advantages of different configurations are thoroughly discussed from the aspects of fabrication technologies and material engineering. Towards the high energy output at a minimal footprint area, a revolutionary design for microbatteries is of great importance. In this perspective, we review the progress of fabricating microbatteries based on the rolled-up nanotechnology, a derivative origami technology. Finally, we discussed the challenges and perspectives in the device design and materials optimization.
Advanced Hybrid GaN/ZnO Nanoarchitectured Microtubes for Fluorescent Micromotors Driven by UV Light
(Weinheim : Wiley-VCH, 2020) Wolff, Niklas; Ciobanu, Vladimir; Enachi, Mihail; Kamp, Marius; Braniste, Tudor; Duppel, Viola; Shree, Sindu; Raevschi, Simion; Medina-Sánchez, Mariana; Adelung, Rainer; Schmidt, Oliver G.; Kienle, Lorenz; Tiginyanu, Ion
The development of functional microstructures with designed hierarchical and complex morphologies and large free active surfaces offers new potential for improvement of the pristine microstructures properties by the synergistic combination of microscopic as well as nanoscopic effects. In this contribution, dedicated methods of transmission electron microscopy (TEM) including tomography are used to characterize the complex hierarchically structured hybrid GaN/ZnO:Au microtubes containing a dense nanowire network on their interior. The presence of an epitaxially stabilized and chemically extremely stable ultrathin layer of ZnO on the inner wall of the produced GaN microtubes is evidenced. Gold nanoparticles initially trigger the catalytic growth of solid solution phase (Ga1– xZnx)(N1– xOx) nanowires into the interior space of the microtube, which are found to be terminated by AuGa-alloy nanodots coated in a shell of amorphous GaOx species after the hydride vapor phase epitaxy process. The structural characterization suggests that this hierarchical design of GaN/ZnO microtubes could offer the potential to exhibit improved photocatalytic properties, which are initially demonstrated under UV light irradiation. As a proof of concept, the produced microtubes are used as photocatalytic micromotors in the presence of hydrogen peroxide solution with luminescent properties, which are appealing for future environmental applications and active matter fundamental studies. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations
(Weinheim : Wiley-VCH, 2020) Zhu, Minshen; Wang, Xiaojie; Tang, Hongmei; Wang, Jiawei; Hao, Qi; Liu, Lixiang; Li, Yang; Zhang, Kai; Schmidt, Oliver G.
Hydrogels are widely used in flexible aqueous batteries due to their liquid-like ion transportation abilities and solid-like mechanical properties. Their potential applications in flexible and wearable electronics introduce a fundamental challenge: how to lower the freezing point of hydrogels to preserve these merits without sacrificing hydrogels' basic advantages in low cost and high safety. Moreover, zinc as an ideal anode in aqueous batteries suffers from low reversibility because of the formation of insulative byproducts, which is mainly caused by hydrogen evolution via extensive hydration of zinc ions. This, in principle, requires the suppression of hydration, which induces an undesirable increase in the freezing point of hydrogels. Here, it is demonstrated that cooperatively hydrated cations, zinc and lithium ions in hydrogels, are very effective in addressing the above challenges. This simple but unique hydrogel not only enables a 98% capacity retention upon cooling down to −20 °C from room temperature but also allows a near 100% capacity retention with >99.5% Coulombic efficiency over 500 cycles at −20 °C. In addition, the strengthened mechanical properties of the hydrogel under subzero temperatures result in excellent durability under various harsh deformations after the freezing process. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Biofunctionalized self-propelled micromotors as an alternative on-chip concentrating system
(Cambridge : Royal Society of Chemistry, 2014) Restrepo-Pérez, Laura; Meyer, Anne K.; Helbig, Linda; Sanchez, Samuel; Schmidt, Oliver G.
Sample pre-concentration is crucial to achieve high sensitivity and low detection limits in lab-on-a-chip devices. Here, we present a system in which self-propelled catalytic micromotors are biofunctionalized and trapped acting as an alternative concentrating mechanism. This system requires no external energy source, which facilitates integration and miniaturization.
Biomimetic microelectronics for regenerative neuronal cuff implants
(Hoboken, NJ : Wiley, 2015) Karnaushenko, Daniil; Münzenrieder, Niko; Karnaushenko, Dmitriy D.; Koch, Britta; Meyer, Anne K.; Baunack, Stefan; Petti, Luisa; Tröster, Gerhard; Makarov, Denys; Schmidt, Oliver G.
Smart biomimetics, a unique class of devices combining the mechanical adaptivity of soft actuators with the imperceptibility of microelectronics, is introduced. Due to their inherent ability to self‐assemble, biomimetic microelectronics can firmly yet gently attach to an inorganic or biological tissue enabling enclosure of, for example, nervous fibers, or guide the growth of neuronal cells during regeneration.
Blood platelet enrichment in mass-producible surface acoustic wave (SAW) driven microfluidic chips
(Cambridge : RSC, 2019) Richard, Cynthia; Fakhfouri, Armaghan; Colditz, Melanie; Striggow, Friedrich; Kronstein-Wiedemann, Romy; Tonn, Torsten; Medina-Sánchez, Mariana; Schmidt, Oliver G.; Gemming, Thomas; Winkler, Andreas
The ability to separate specific biological components from cell suspensions is indispensable for liquid biopsies, and for personalized diagnostics and therapy. This paper describes an advanced surface acoustic wave (SAW) based device designed for the enrichment of platelets (PLTs) from a dispersion of PLTs and red blood cells (RBCs) at whole blood concentrations, opening new possibilities for diverse applications involving cell manipulation with high throughput. The device is made of patterned SU-8 photoresist that is lithographically defined on the wafer scale with a new proposed methodology. The blood cells are initially focused and subsequently separated by an acoustic radiation force (ARF) applied through standing SAWs (SSAWs). By means of flow cytometric analysis, the PLT concentration factor was found to be 7.7, and it was proven that the PLTs maintain their initial state. A substantially higher cell throughput and considerably lower applied powers than comparable devices from literature were achieved. In addition, fully coupled 3D numerical simulations based on SAW wave field measurements were carried out to anticipate the coupling of the wave field into the fluid, and to obtain the resulting pressure field. A comparison to the acoustically simpler case of PDMS channel walls is given. The simulated results show an ideal match to the experimental observations and offer the first insights into the acoustic behavior of SU-8 as channel wall material. The proposed device is compatible with current (Lab-on-a-Chip) microfabrication techniques allowing for mass-scale, reproducible chip manufacturing which is crucial to push the technology from lab-based to real-world applications. © The Royal Society of Chemistry.
Carbonate-based Janus micromotors moving in ultra-light acidic environment generated by HeLa cells in situ
(London : Nature Publishing Group, 2016) Guix, Maria; Meyer, Anne K.; Koch, Britta; Schmidt, Oliver G.
Novel approaches to develop naturally-induced drug delivery in tumor environments in a deterministic and controlled manner have become of growing interest in recent years. Different polymeric-based microstructures and other biocompatible substances have been studied taking advantage of lactic acidosis phenomena in tumor cells, which decrease the tumor extracellular pH down to 6.8. Micromotors have recently demonstrated a high performance in living systems, revealing autonomous movement in the acidic environment of the stomach or moving inside living cells by using acoustic waves, opening the doors for implementation of such smart microengines into living entities. The need to develop biocompatible motors which are driven by natural fuel sources inherently created in biological systems has thus become of crucial importance. As a proof of principle, we here demonstrate calcium carbonate Janus particles moving in extremely light acidic environments (pH 6.5), whose motion is induced in conditioned acidic medium generated by HeLa cells in situ. Our system not only obviates the need for an external fuel, but also presents a selective activation of the micromotors which promotes their motion and consequent dissolution in presence of a quickly propagating cell source (i.e. tumor cells), therefore inspiring new micromotor configurations for potential drug delivery systems.
Charge transport in organic nanocrystal diodes based on rolled-up robust nanomembrane contacts
(Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2017-6-19) Bandari, Vineeth Kumar; Varadharajan, Lakshmi; Xu, Longqian; Jalil, Abdur Rehman; Devarajulu, Mirunalini; Siles, Pablo F.; Zhu, Feng; Schmidt, Oliver G.
The investigation of charge transport in organic nanocrystals is essential to understand nanoscale physical properties of organic systems and the development of novel organic nanodevices. In this work, we fabricate organic nanocrystal diodes contacted by rolled-up robust nanomembranes. The organic nanocrystals consist of vanadyl phthalocyanine and copper hexadecafluorophthalocyanine heterojunctions. The temperature dependent charge transport through organic nanocrystals was investigated to reveal the transport properties of ohmic and space-charge-limited current under different conditions, for instance, temperature and bias
Compact helical antenna for smart implant applications
(London : Nature Publishing Group, 2015) Karnaushenko, Dmitriy D.; Karnaushenko, Daniil; Makarov, Denys; Schmidt, Oliver G.
Smart implants are envisioned to revolutionize personal health care by assessing physiological processes, for example, upon wound healing, and communicating these data to a patient or medical doctor. The compactness of the implants is crucial to minimize discomfort during and after implantation. The key challenge in realizing small-sized smart implants is high-volume cost- and time-efficient fabrication of a compact but efficient antenna, which is impedance matched to 50 Ω, as imposed by the requirements of modern electronics. Here, we propose a novel route to realize arrays of 5.5-mm-long normal mode helical antennas operating in the industry-scientific-medical radio bands at 5.8 and 2.4 GHz, relying on a self-assembly process that enables large-scale high-yield fabrication of devices. We demonstrate the transmission and receiving signals between helical antennas and the communication between an antenna and a smartphone. Furthermore, we successfully access the response of an antenna embedded in a tooth, mimicking a dental implant. With a diameter of ~0.2 mm, these antennas are readily implantable using standard medical syringes, highlighting their suitability for in-body implant applications.
A compact tube-in-tube microsized lithium-ion battery as an independent microelectric power supply unit
([New York, NY] : Elsevier, 2021) Weng, Qunhong; Wang, Sitao; Liu, Lixiang; Lu, Xueyi; Zhu, Minshen; Li, Yang; Gabler, Felix; Schmidt, Oliver G.
Independent and well-packaged miniaturized energy storage devices (MESDs) are indispensable as power sources or backup units for integrated circuits and many dispersive electronics applications. Challenges associated with MESD development relate to their low packaged areal energy density and poor battery performance. Here, we propose a compact tube-in-tube battery configuration to overcome the areal energy density and packaging problems in microbatteries. Compact microtubular microelectrodes rolled up from patterned nanomembranes are sealed in an inert glass capillary with a thin tube wall. The resultant tube-in-tube microsized lithium-ion batteries (micro-LIBs), based on various active materials, exhibit very high and scalable packaged areal energy densities up to 605 microampere hours per square centimeter (μAh cm−2) or 313 μWh cm−2 with footprints as small as 0.39–0.79 mm2. This approach is a practical alternative for microbattery microelectrode, packaging, and configuration innovations.
Coupling of chiralities in spin and physical spaces: The Möbius ring as a case study
(College Park : American Physical Society, 2015) Pylypovskyi, Oleksandr V.; Kravchuk, Volodymyr P.; Sheka, Denis D.; Makarov, Denys; Schmidt, Oliver G.; Gaididei, Yuri
We show that the interaction of the magnetic subsystem of a curved magnet with the magnet curvature results in the coupling of a topologically nontrivial magnetization pattern and topology of the object. The mechanism of this coupling is explored and illustrated by an example of a ferromagnetic Möbius ring, where a topologically induced domain wall appears as a ground state in the case of strong easy-normal anisotropy. For the Möbius geometry, the curvilinear form of the exchange interaction produces an additional effective Dzyaloshinskii-like term which leads to the coupling of the magnetochirality of the domain wall and chirality of the Möbius ring. Two types of domain walls are found, transversal and longitudinal, which are oriented across and along the Möbius ring, respectively. In both cases, the effect of magnetochirality symmetry breaking is established. The dependence of the ground state of the Möbius ring on its geometrical parameters and on the value of the easy-normal anisotropy is explored numerically.
Covalent Organic Frameworks for Efficient Energy Electrocatalysis: Rational Design and Progress
(Weinheim : Wiley-VCH, 2021) Zhang, Hua; Zhu, Minshen; Schmidt, Oliver G.; Chen, Shuillang; Zhang, Kai
An efficient catalyst with a precisely designed and predictable structure is highly desired to optimize its performance and understand the mechanism beyond the catalytic activity. Covalent organic frameworks (COFs), as an emerging class of framework materials linked by strong covalent bonds, simultaneously allow precise structure design with predictable synthesis and show advantages of large surface areas, tunable pore sizes, and unique molecular architectures. Although the research on COF‐based electrocatalysts is at an early age, significant progress has been made. Herein, the recent significant progress in the design and synthesis of COFs as highly efficient electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is summarized. Design principles for COFs as efficient electrocatalysts are discussed by considering essential factors for catalyzing the OER, ORR, and HER processes at the molecular level. Herein, a summary on the in‐depth understanding of the catalytic mechanism and kinetics limitations of COFs provides a general instruction for further exploring their vast potential for designing highly efficient electrocatalysts.
Deposition of exchange-coupled dinickel complexes on gold substrates utilizing ambidentate mercapto-carboxylato ligands
(Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2017) Börner, Martin; Blömer, Laura; Kischel, Marcus; Richter, Peter; Salvan, Georgeta; Zahn, Dietrich R. T.; Siles, Pablo F.; Fuentes, Maria E. N.; Bufon, Carlos C. B.; Grimm, Daniel; Schmidt, Oliver G.; Breite, Daniel; Abel, Bernd; Kersting, Berthold
The chemisorption of magnetically bistable transition metal complexes on planar surfaces has recently attracted increased scientific interest due to its potential application in various fields, including molecular spintronics. In this work, the synthesis of mixed-ligand complexes of the type [NiII2L(L’)](ClO4), where L represents a 24-membered macrocyclic hexaazadithiophenolate ligand and L’ is a ω-mercapto-carboxylato ligand (L’ = HS(CH2)5CO2− (6), HS(CH2)10CO2− (7), or HS(C6H4)2CO2− (8)), and their ability to adsorb on gold surfaces is reported. Besides elemental analysis, IR spectroscopy, electrospray ionization mass spectrometry (ESIMS), UV–vis spectroscopy, and X-ray crystallography (for 6 and 7), the compounds were also studied by temperature-dependent magnetic susceptibility measurements (for 7 and 8) and (broken symmetry) density functional theory (DFT) calculations. An S = 2 ground state is demonstrated by temperature-dependent susceptibility and magnetization measurements, achieved by ferromagnetic coupling between the spins of the Ni(II) ions in 7 (J = +22.3 cm−1) and 8 (J = +20.8 cm−1; H = −2JS1S2). The reactivity of complexes 6–8 is reminiscent of that of pure thiolato ligands, which readily chemisorb on Au surfaces as verified by contact angle, atomic force microscopy (AFM) and spectroscopic ellipsometry measurements. The large [Ni2L] tail groups, however, prevent the packing and self-assembly of the hydrocarbon chains. The smaller film thickness of 7 is attributed to the specific coordination mode of the coligand. Results of preliminary transport measurements utilizing rolled-up devices are also reported.
Digital Electrochemistry for On-Chip Heterogeneous Material Integration
(Weinheim : Wiley-VCH, 2021) Bao, Bin; Rivkin, Boris; Akbar, Farzin; Karnaushenko, Dmitriy D.; Bandari, Vineeth Kumar; Teuerle, Laura; Becker, Christian; Baunack, Stefan; Karnaushenko, Daniil; Schmidt, Oliver G.
Many modern electronic applications rely on functional units arranged in an active-matrix integrated on a single chip. The active-matrix allows numerous identical device pixels to be addressed within a single system. However, next-generation electronics requires heterogeneous integration of dissimilar devices, where sensors, actuators, and display pixels sense and interact with the local environment. Heterogeneous material integration allows the reduction of size, increase of functionality, and enhancement of performance; however, it is challenging since front-end fabrication technologies in microelectronics put extremely high demands on materials, fabrication protocols, and processing environments. To overcome the obstacle in heterogeneous material integration, digital electrochemistry is explored here, which site-selectively carries out electrochemical processes to deposit and address electroactive materials within the pixel array. More specifically, an amorphous indium-gallium-zinc oxide (a-IGZO) thin-film-transistor (TFT) active-matrix is used to address pixels within the matrix and locally control electrochemical reactions for material growth and actuation. The digital electrochemistry procedure is studied in-depth by using polypyrrole (PPy) as a model material. Active-matrix-driven multicolored electrochromic patterns and actuator arrays are fabricated to demonstrate the capabilities of this approach for material integration. The approach can be extended to a broad range of materials and structures, opening up a new path for advanced heterogeneous microsystem integration.
Dimensionality of rolled-up nanomembranes controls neural stem cell migration mechanism
(Washington D.C. : American Chemical Society, 2015) Koch, Britta; Meyer, Anne K.; Helbig, Linda; Harazim, Stefan M.; Storch, Alexander; Sanchez, Samuel; Schmidt, Oliver G.
We employ glass microtube structures fabricated by rolledup nanotechnology to infer the influence of scaffold dimensionality and cell confinement on neural stem cell (NSC) migration. Thereby, we observe a pronounced morphology change that marks a reversible mesenchymal to amoeboid migration mode transition. Space restrictions preset by the diameter of nanomembrane topography modify the cell shape toward characteristics found in living tissue. We demonstrate the importance of substrate dimensionality for the migration mode of NSCs and thereby define rolled-up nanomembranes as the ultimate tool for single-cell migration studies.
Direct imaging of nanoscale field-driven domain wall oscillations in Landau structures
(Cambridge : RSC Publ., 2022) Singh, Balram; Ravishankar, Rachappa; Otálora, Jorge A.; Soldatov, Ivan; Schäfer, Rudolf; Karnaushenko, Daniil; Neu, Volker; Schmidt, Oliver G.
Linear oscillatory motion of domain walls (DWs) in the kHz and MHz regime is crucial when realizing precise magnetic field sensors such as giant magnetoimpedance devices. Numerous magnetically active defects lead to pinning of the DWs during their motion, affecting the overall behavior. Thus, the direct monitoring of the domain wall's oscillatory behavior is an important step to comprehend the underlying micromagnetic processes and to improve the magnetoresistive performance of these devices. Here, we report an imaging approach to investigate such DW dynamics with nanoscale spatial resolution employing conventional table-top microscopy techniques. Time-averaged magnetic force microscopy and Kerr imaging methods are applied to quantify the DW oscillations in Ni81Fe19 rectangular structures with Landau domain configuration and are complemented by numeric micromagnetic simulations. We study the oscillation amplitude as a function of external magnetic field strength, frequency, magnetic structure size, thickness and anisotropy and understand the excited DW behavior as a forced damped harmonic oscillator with restoring force being influenced by the geometry, thickness, and anisotropy of the Ni81Fe19 structure. This approach offers new possibilities for the analysis of DW motion at elevated frequencies and at a spatial resolution of well below 100 nm in various branches of nanomagnetism.
Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics
(Hoboken, NJ : Wiley, 2015) Melzer, Michael; Karnaushenko, Daniil; Lin, Gungun; Baunack, Stefan; Makarov, Denys; Schmidt, Oliver G.
A novel fabrication method for stretchable magnetoresistive sensors is introduced, which allows the transfer of a complex microsensor systems prepared on common rigid donor substrates to prestretched elastomeric membranes in a single step. This direct transfer printing method boosts the fabrication potential of stretchable magnetoelectronics in terms of miniaturization and level of complexity, and provides strain‐invariant sensors up to 30% tensile deformation.

Browsing by Author "Schmidt, Oliver G."

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