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Highly compliant electronics, naturally conforming to human skin, represent a paradigm shift in the interplay with our surroundings. Solution-processable printing technologies are yet to be developed to comply with extreme requirements to mechanical conformability of on-skin appliances. Here, we demonstrate the first highly-compliant, printable and stretchable giant magnetoresistive (GMR) sensors capable of detection in low magnetic field and sustaining high-performance magneto-resistive sensing under extreme mechanical deformation of up to 16 µm of bending radii and 100% of stretching state. These printable giant magnetoresistive sensors exhibit 2 orders of magnitude boost in sensitivity to small magnetic field (0.88 mT) with excellent mechanical compliance in comparison with state-of-the-art printable magnetic field sensors. We feature the potential of our highly-compliant and printable magnetoresistive sensors in augmented reality settings, where a sensor-functionalized finger conducts remote and touchless control of virtual objects manageable for scrolling electronic documents and zooming maps under tiny permanent magnet.

M. Ha, G. S. Cañón Bermúdez, T. Kosub, I. Mönch, Y. Zabila, E. S. Oliveros Mata, R. Illing, Y. Wang, J. Fassbender, and D. Makarov
Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics
Adv. Mater. 33, 2005521 (2021). URL PDF

Actuation-assisted bioanalysis represents an emerging application of micromachines, including microactuators, motors, and microrobotic devices. Here, micromachines consisting of tailorable microcompartments are synthesized by microfluidics-directed assembly. Apart from the control over the geometric parameters of the compartments, a novel emulsion fission approach is devised to precisely allocate the magnetic content in between the compartments of the dimer structures. This unlocks a couple of new degrees of freedom to engineer magnetic coupling in discrete magnetic structure assemblies and uncovers a series of multifunctional microactuators for complex and dynamic bioanalysis.

This work is a result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., The University of Technology Sydney (group of Dr. Gungun Lin and Prof. Dayong Jin) and State Key Laboratory of Rare Earth Resource Utilization of the Chinese Academy of Sciences (group of Prof. Jun Lin).

G. Lin, Y. Liu, G. Huang, Y. Chen, D. Makarov, J. Lin, Z. Quan, and D. Jin
3D Rotation-Trackable and Differentiable Micromachines with Dimer-Type Structures for Dynamic Bioanalysis
Advanced Intelligent Systems 3, 2000205 (2021). URL PDF

We report that stray magnetic fields can code and decode a collection of hierarchically-assembled beads. By the microfluidic assembling of mesoscopic superparamagnetic cores, diverse and non-volatile stray magnetic field response can be built in the series of microscopic spheres, dumbbells, pears, chains and triangles. Remarkably, the set of stray magnetic field fingerprints are readily discerned by a compact giant magnetoresistance sensor for parallelised screening of multiple distinctive pathogenic DNAs. This opens up the magneto-multiplexing opportunity and could enable streamlined assays to incorporate magneto-mixing, washing, enrichment and separation of analytes. This strategy therefore suggests a potential point-of-care testing solution for efficient kinetic assays.

This work is a result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., The University of Technology Sydney (group of Dr. Gungun Lin and Prof. Dayong Jin) and Minomic International Ltd. (group of Bradley J. Walsh).

Y. Liu, G. Lin, Y. Chen, I. Mönch, D. Makarov, B. J. Walsh, and D. Jin
Coding and decoding stray magnetic fields for multiplexing kinetic bioassay platform
Lab Chip 20, 4561 (2020). URL   

We realized a droplet-based magnetofluidic platform based on planar Hall effect (PHE) sensors. We applied this platform for the detection and analysis of nanoliter-sized superparamagnetic droplets encapsulating a ferrofluid composed of 10 nm Fe3O4 nanoparticles at concentrations ranging from 0.04 to 5 mg/cm³. These concentrations are chosen due to their relevance for biological and medical applications like cancer thermotherapy and Magnetic Resonance Imaging (MRI). We examined the sensor response to moving superparamagnetic droplets even without external biasing just in the geomagnetic field and demonstrate the detection of droplets at concentrations down to 0.58 mg/cm³. With this performance, our detection platform with geomagnetic field biasing (50 µT) outperforms by 10 times the state-of-the-art devices in droplet-based magnetofluidics with integrated GMR sensors yet biased to 1 mT fields. The detection limit of our platform can be pushed down to 0.04 mg/cm³ when biased with an external magnetic field of 5 mT, which constitutes 2 orders of magnitude enhancement over the state-of-the-art in droplet-based magnetofluidics. These results open the route for new strategies of the utilization of ferrofluids in microfluidic geometries in e.g. bio(-chemical) or medical applications.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., Bar-Ilan University (group of Prof. Lior Klein), Ben-Gurion University of the Negev (group of Dr. Asaf Grosz) and Instituto Nacional de Technologia Industrial (group of Pablo N. Granell).

J. Schütt, R. Illing, O. Volkov, T. Kosub, P. N. Granell, H. Nhalil, J. Fassbender, L. Klein, A. Grosz, and D. Makarov
Two orders of magnitude boost in the detection limit of droplet-based micro-magnetofluidics with planar Hall Effect sensors
ACS Omega 5, 20609 (2020). URL PDF   

We introduced a novel strategy to fabricate Janus micromotors through a microfluidic method by adhering functional nanoparticles (NPs) onto microspheres functionalized with a photocurable hydrogel precursor. The proposed approach allows us to fabricate Janus particles with tunable coverage of a hydrogel sphere with functional NPs (including photocatalytic TiO2, magnetic Fe3O4 and catalytic MnO2), hence enabling a straightforward tailoring of physical and chemical responses of the capped spheres under external stimuli (UV light illumination, concentration of H2O2 and magnetic field). The method can be readily extended to prepare multifunctional Janus micromotors by using various kinds of functional NPs (e.g., catalytic MnO2 and magnetic Fe3O4) during the fabrication. In addition to the detailed study of the fundamentals of the complex motion dynamics of Janus spheres, we revealed the potential of our TiO2 Janus microspheres for performing useful tasks in environmental applications with the focus on water purification.

This work is a result of a fruitful cooperation between the HZDR and the group of Prof. Yongfeng Mei at the Fudan University in Shanghai, China.

X. Lin, H. Zhu, Z. Zhao, C. You, Y. Kong, Y. Zhao, J. Liu, H. Chen, X. Shi, D. Makarov, and Y. F. Mei
Hydrogel-based Janus Micromotors Capped with Functional Nanoparticles for Environmental Applications
Adv. Mater. Technol. 5, 2000279 (2020). URL PDF   

Synthetic nano- and micromotors interact with each other and their surroundings in a complex manner. We quantitatively investigate a repulsive behavior between immobile yet photocatalytic Ag/AgCl capped Janus particles embedded in a dense matrix of passive silica beads in pure water. As a result of the photocatalytic reaction, passive beads are repelled away from active Janus particles which can perform rotational but no translational motion. These results will be helpful for deeper understanding of complex interactions between active and passive particles in various soft matter systems, including those containing synthetic and biological active microswimmers like sperm cell, algae, bacterial or motor proteins, under realistic conditions.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden University of Technology (group of Dr. Larysa Baraban), Vrije Universiteit Brussel (Dr. Vyacheslav R. Misko), RIKEN Cluster for Pioneering Research (Prof. Franco Nori).

T. Huang, S. Gobeil, X. Wang, V. Misko, F. Nori, W. De Malsche, J. Fassbender, D. Makarov, G. Cuniberti, and L. Baraban
Anisotropic exclusion effect between photocatalytic Ag/AgCl Janus particles and passive beads in a dense colloidal matrix
Langmuir 36, 7091 (2020). URL   

Here we realize periodic magnetic domain structures in sub-200 nm wide linear as well as curved magnets, embedded within a flat non-ferromagnetic thin film. The nanomagnets are produced within a non-ferromagnetic B2-ordered Fe60Al40 thin film, where local irradiation by a focused ion beam causes the formation of disordered and strongly ferromagnetic regions of A2 Fe60Al40. We study anisotropic lattice relaxation, which generates a magnetic easy-axis parallel to the short axis. The competing effect of the strain and shape anisotropies stabilizes a periodic domain pattern in linear as well as spiral nanomagnets, providing a versatile and geometrically controllable path to engineering the strain and thereby the magnetic anisotropy at the nanoscale.

This work is a result of a fruitful cooperation of the HZDR team with the University of Glasgow and University of Antwerp.

M. Nord, A. Semisalova, A. Kákay, G. Hlawacek, I. MacLaren, V. Liersch, O. M. Volkov, D. Makarov, G. W. Paterson, K. Potzger, J. Lindner, J. Fassbender, D. McGrouther, and R. Bali
Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets
Small 15, 1904738 (2019). URL PDF   

Numerous flexible diagnostic or therapeutic devices have been already successfully demonstrated. However, cancer treatment remains rather unexplored in the field of flexible electronics. Here, we propose an approach to targeted cancer treatment which relies on the implantation at the tumor site of an ultra-thin flexible device comprising a resistive heater and temperature sensor. The device is fabricated on a 6 micrometer thick polymeric foil, which seamlessly conforms to the very soft liver tissue and allows for precisely controlled thermal treatment. We demonstrate a proof-of-concept prototype and evaluate its electrical and mechanical performance when applied to murine models. The presented multifunctional and highly compliant device paves the way for targeting of exophytic tumor nodules via thermal destruction of tissue, targeted drug release, or enhancement of anti-tumor immune responses. In addition, it raises the possibility to further study the effects of thermal treatment in enhancing the development of the new cancer therapies, especially for severe malignancies as liver cancer.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V. and Hannover Medical School (groups of Dr. T. Yevsa and Dr. Dr. A. Potthoff).

G. S. Cãnón Bermudez, A. Kruv, T. Voitsekhivska, I. Hochnadel, A. Lebanov, A. Potthoff, J. Fassbender, T. Yevsa, and D. Makarov
Implantable Highly Compliant Devices for Heating of Internal Organs: Toward Cancer Treatment
Adv. Eng. Mater. 21, 1900407 (2019). URL    

We here demonstrate the experimental and theoretical study of the curvature effects in planar magnetic parabolic stripes. We show that a proper design of magnetic patterns reveal curvature-driven changes of static magnetic properties in parabolic nanostripes. The shape of a parabolic stripe is tuned to cover broad range of widths and curvatures allowing to construct a phase diagram of magnetic equilibrium states. For this, joint experimental, i.e. soft X-ray imaging, and theoretical studies are carried out. Analytical calculations in the framework, when non-local magnetostatic effects are neglected, coincide with the experimental and simulation results in a broad range of parameters. Our results give confidence in the applicability of the existing theoretical framework for further analytical considerations of equilibrium magnetization states of curvilinear nanomagnets.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V. and Helmholtz-Zentrum Berlin für Materialien und Energie (group of Dr. Florian Kronast).

O. M. Volkov, F. Kronast, I. Mönch, M.-A. Mawass, A. Kakay, J. Fassbender, and D. Makarov
Experimental and theoretical study of curvature effects in parabolic nanostripes
Physica Status Solidi (RRL) - Rapid Research Letters 13, 1800309 (2019) URL PDF   

We demonstrate plasmonic Ag/AgCl based spherical Janus motors that reveal efficient propulsion when illuminated by visible light. We show that a proper design of an AgCl based microswimmer can boost the mean squared displacements (MSD) reaching 800 µm2 within 8 s, which is 100x higher compared to previous visible light-driven Janus micromotors and 7x higher than reported ultraviolet (UV) light-driven AgCl micromotors. The application potential of Ag/AgCl micromotors in various physiological solutions and polluting agents is addressed.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden University of Technology (group of Dr. Larysa Baraban), University of Antwerpen (Dr. Vyacheslav R. Misko), RIKEN Cluster for Pioneering Research (Prof. Franco Nori) and Leibniz Institute of Polymer Research Dresden (Dr. P. Formanek).

X. Wang, L. Baraban, A. Nguyen, J. Ge, V. R. Misko, J. Tempere, F. Nori, P. Formanek, T. Huang, G. Cuniberti, J. Fassbender, and D. Makarov
High-motility visible light-driven Ag/AgCl Janus micromotors
Small 14, 1803613 (2018).  URL   

We here demonstrated for the first time electronic skins capable of perceiving direction in space based on the interaction with geomagnetic field exclusively. In this respect, we realized a highly compliant e-skin compass relying on geometrically conditioned anisotropic magnetoresistive (AMR) sensors fabricated on ultra-thin polymeric foils. Our highly compliant magnetosensory system enables real time tracking of the position of a body in space as well as the touchless manipulation of virtual objects based on the biomagnetic orientation as needed for virtual and augmented reality applications.

G. S. Cañón Bermúdez, H. Fuchs, L. Bischoff, J. Fassbender, and D. Makarov
Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics
Nature Electronics 1, 589 (2018).  URL  Link    

Inspired by the active matter in biological systems, there is an intensive research of the collective behavior between self-propelled artificial objects and nonmotile passive beads. Here, we show that visible-light-actuated plasmonic Ag/AgCl-based Janus micromotors reveal efficient exclusion effect to the surrounding passive polystyrene (PS) beads in pure water. We demonstrate experimentally, that the exclusion efficiency is controlled by the number of single Janus PS/Ag/AgCl particles that compose a cluster. The clear-cut comparison between the theoretical analysis of motion and experimental observation allows us to determine not only the diffusion constants, but also the system-specific interaction parameter between Janus motors and passive beads. This parameter is absolutely crucial as it provides predictive power for the further theoretical insights in the complex dynamics of these active-passive systems. The observed efficient visible light-driven exclusion in the active-passive system can be further applied for biological studies, such as the investigation of the interaction between motile micromotors and bio objects.

This work is the result of a fruitful cooperation between the Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden University of Technology (group of Dr. Larysa Baraban), University of Antwerpen (Dr. Vyacheslav R. Misko), RIKEN Cluster for Pioneering Research (Prof. Franco Nori).

X. Wang, L. Baraban, V. R. Misko, F. Nori, T. Huang, G. Cuniberti, J. Fassbender, and D. Makarov
Visible light actuated efficient exclusion between plasmonic Ag/AgCl micromotors and passive beads
Small 14, 1802537 (2018).  URL      

Among a wide choice of fundamental biosensing principles, magnetic sensing technologies enabled by magnetic field sensors and magnetic particles offer attractive advantages. Key features of a magnetic sensing format include the use of commercially-available magnetic field sensing elements, e.g. magnetoresistive sensors bearing huge potential for compact integration, a magnetic field sensing mechanism that is free from interference by complex biomedical samples, and an additional degree of freedom for the on-chip handling of biochemical species rendered by magnetic labels. In this review, we highlight the historical basis, routes, recent advances and applications of magnetic biosensing platform technologies based on magnetoresistive sensors.

G. Lin, D. Makarov, and O. G. Schmidt
Magnetic sensing platform technologies for biomedical applications
Lab Chip 17, 1884 (2017).  URL      

Self-propelled Janus particles, acting as microscopic vehicles, have the potential of performing complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on chip chemical computer, or in vivo drug delivery. Development of these smart nano-devices requires a better understanding of how synthetic swimmers move in crowded and confined geometry that mimic actual microenvironment. We demonstrate experimentally and in simulations the intriguing transport phenomena, observed while placing both, catalytic Janus swimmers and passive particles into narrow channels confinement. This work represents an important milestone towards understanding and further fabrication of realistic bioinspired complex networks, containing synthetic autonomous micro- and nano- machines to perform the tasks in a mixture with passive objects.

This work is the result of a fruitful cooperation between the Dresden University of Technology (group of Dr. Larysa Baraban), University of Antwerpen (group of Dr. Misko), Tongji University (Prof. Marchesoni), University of Michigan (Prof. Nori), and Helmholtz-Zentrum Dresden-Rossendorf e.V.

H. Yu, A. Kopach, V. R. Misko, A. A. Vasylenko, D. Makarov, F. Marchesoni, F. Nori, L. Baraban, and G. Cuniberti
Confined catalytic Janus swimmers in a crowded channel: Geometry-driven rectification transients and directional locking
Small 12, 5882 (2016).  URL      

We demonstrated a logic-controlled magnetic flow cytometric system for controlled synthesis of magnetic encoded microcarriers in multiphase flow networks. The system provides a first solution for the quality administration and screening of magnetic suspension arrays and addresses the universal need of process control in microfluidic networks.

G. Lin, D. D. Karnaushenko, G. S. Cañón Bermúdez, O. G. Schmidt, D. Makarov
Magnetic suspension array technology: Controlled synthesis and screening in microfluidic networks
Small 12, 4553 (2016)  URL PDF     

We realized the first entirely flexible integrated magnetic field sensor system consisting of a flexible giant magnetoresistive bridge on-site conditioned using high-performance IGZO-based readout electronics. With the remarkable sensitivity of 25 V/V/kOe, the system outperforms commercial fully integrated rigid magnetic sensors by at least one order of magnitude, whereas all components stay fully functional when bend to a radius of 5 mm.

N. Münzenrieder, D. Karnaushenko, L. Petti, G. Cantarella, C. Vogt, L. Büthe, D.D. Karnaushenko, O. G. Schmidt, D. Makarov, G. Tröster
Entirely flexible on-site conditioned magnetic sensorics
Adv. Electron. Mater. 2, 1600188 (2016).  URL PDF     

We introduced smart biomimetics – a unique class of devices combining mechanical adaptivity of soft actuators with the imperceptibility of microelectronics. Due to the inherent ability to self-assemble, biomimetic microelectronics can firmly yet gently attach to an inorganic or biological tissue enabling enclosure of, e.g. nervous fibers, or guiding the growth of neuronal cells during regeneration.

D. Karnaushenko, N. Münzenrieder, D. D. Karnaushenko, B. Koch, A. K. Meyer, S. Baunack, L. Petti, G. Tröster, D. Makarov, O. G. Schmidt
Biomimetic microelectronics for regenerative neuronal cuff implants
Adv. Mater. 27, 6797 (2015).  URL PDF     

A flexible light weight diagnostic platform is realized on cost-efficient large-area flexible foils enabling its cost-efficient high-volume delivery to medical institutions worldwide. The devices allow the timely diagnosis of viral or infectious diseases, for example, the here demonstrated H1N1 subtype of the Avian Influenza Virus. 

D. Karnaushenko, B. Ibarlucea, S. Lee, G. Lin, L. Baraban, S. Pregl, M. Melzer, D. Makarov, T. Mikolajick, O. G. Schmidt, G. Cuniberti
Light weight and flexible high-performance diagnostic platform
Adv. Healthcare Mater. 4, 1517 (2015) URL PDF

Highly flexible bismuth Hall sensors on polymeric foils are fabricated, and the key optimization steps that are required to boost their sensitivity to the bulk value are identified. The sensor can be bent around the wrist or positioned on the finger to realize an interactive pointing device for wearable electronics. Furthermore, this technology is of great interest for the rapidly developing market of ­eMobility, for optimization of eMotors and magnetic bearings.

M. Melzer, D. Karnaushenko, G. Lin, S. Baunack, D. Makarov, O. G. Schmidt
Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics
Adv. Mater. 27, 1333 (2015) URL PDF

High-performance giant magnetoresistive (GMR) sensorics are realized, which are printed at predefined locations on flexible circuitry. Remarkably, the printed magnetosensors remain fully operational over the complete consumer temperature range and reveal a giant magnetoresistance up to 37% and a sensitivity of 0.93 T?1 at 130 mT. With these specifications, printed magnetoelectronics can be controlled using flexible active electronics for the realization of smart packaging and energy-efficient switches.

D. Karnaushenko, D. Makarov, M. Stöber, D. D. Karnaushenko, S. Baunack, O. G. Schmidt
High-performance magnetic sensorics for printable and flexible electronics
Adv. Mater. 27, 880 (2015) URL PDF

We fabricated permalloy (Fe19Ni81) nanomembranes rolled-up into compact three-dimensional architectures. Our experimental study highlights the dominant influence of the magnetostatic interaction between multiple windings of rolled-up nanomembranes inducing the anti-parallel alignment of the magnetic moments between adjacent layers of the rolled-up tube. This leads to geometrically induced complex spiral-like magnetic domains.

R. Streubel, D. Makarov, J. Lee, C. Müller, M. Melzer, R. Schäfer, C. C. B. Bufon, S.-K. Kim, O. G. Schmidt
Rolled-up permalloy nanomembranes with multiple windings
SPIN 3, 1340001 (2013) URL PDF

A large variety of electronic components assembled as printable optoelectronic devices and communication modules are already commercially available. However, the element responding to a magnetic field has been realized only very recently. Here, we position the novel topic of printable magnetic sensorics in a family of printable electronics and highlight possible application directions of this technology.

D. Makarov, D. Karnaushenko, O. G. Schmidt
Printable magnetoelectronics
ChemPhysChem 14, 1771 (2013) URL PDF