Search

To maintain the downscaling of microelectronic devices with footprints less than one square millimeter, next-generation microbatteries should occupy the same area and deliver adequate energy for running a new generation of multi-functional microautonomous systems. However, the current microbattery technology fails in accomplishing this task because the micrometer-sized electrodes are not compatible with on-chip integration protocols and technologies. To tackle this critical challenge, an on-chip Swiss-roll microelectrode architecture is employed that exploits the self-assembly of thin films into ultra-compact device architectures. A twin-Swiss-roll microelectrode on a chip occupies a footprint of 0.045 mm

Understanding interactions between molecular transition and intense electromagnetic fields confined by plasmon nanostructures is of great significance due to their huge potential in fundamental cavity quantum electrodynamics and practical applications. Here, we report reorientable plasmon-enhanced fluorescence leveraging the flexibilities in densely-packed gold nanogap arrays by template-assisted depositions. By finely adjusting the symmetry of the unit structure, arrays of nanogaps along two nearly-orthogonal axes can be tailored collectively with spacing down to sub-10 nm on a single chip, facilitating distinct "inter-cell" and "intra-cell" plasmon couplings. Through engineering two sets of nanogaps, the varying hybridization-induced plasmonic bonding modes lead to adjustable splitting of the fluorescence emission peak with a width up to 81 nm and narrowing of linewidths up to a factor of 3. Besides, polarization anisotropy with a ratio up to 63% is obtained on the basis of spectrally separated local hotspots with discrepant oscillation directions. The developed plasmonic nanogap array is envisaged to provide a promising chip-scale, cost-effective platform for advancing fluorescence-based detection and emission technologies in both classical and quantum regimes.

Cellular micromotors are attractive for locally delivering high concentrations of drug, and targeting hard-to-reach disease sites such as cervical cancer and early ovarian cancer lesions by non-invasive means. Spermatozoa are highly efficient micromotors perfectly adapted to traveling up the female reproductive system. Indeed, bovine sperm-based micromotors have shown potential to carry drugs toward gynecological cancers. However, due to major differences in the molecular make-up of bovine and human sperm, a key translational bottleneck for bringing this technology closer to the clinic is to transfer this concept to human material. Here, we successfully load human sperm with Doxorubicin (DOX) and perform treatment of 3D cervical cancer and patient-representative ovarian cancer cell cultures, resulting in strong anticancer cell effects. Additionally, we define the subcellular localization of the chemotherapeutic drug within human sperm, using high-resolution optical microscopy. We also assess drug effects on sperm motility and viability over time, employing sperm samples from healthy donors as well as assisted reproduction patients. Finally, we demonstrate guidance and release of human drug-loaded sperm onto cancer tissues using magnetic microcaps, and show the sperm microcap loaded with a second anticancer drug, camptothecin (CPT), which unlike DOX is not suitable for directly loading into sperm due to its hydrophobic nature. This co-drug delivery approach opens up novel targeted combinatorial drug therapies for future applications. © 2020 The Royal Society of Chemistry.

Integrating nanostructured Si materials into a freestanding membrane with high mechanical strength and a continuous conductive network is a promising but challenging route to achieve high energy density lithium ion batteries (LIBs). Herein, we demonstrate that physical vapor deposition (PVD) customized two-dimensional (2D) porous amorphous Si nanoflakes, reinforced with ultralong multiwalled carbon nanotubes (MWCNTs), can be integrated into a freestanding film electrode with high volumetric/areal capacity and energy density. Owing to the special 1D/2D nanotube/nanoflake entangled architecture, the freestanding Si–MWCNT film is highly porous, electrically conductive, and mechanically robust. Moreover, the interconnected MWCNT network functions as a spacer to prevent adjacent Si nanoflakes from restacking, and the 2D porous Si nanoflakes provide a large electrode/electrolyte contact area, both of which enable fast Li+ transportation. Due to the existence of abundant pores in both amorphous Si nanoflakes (mesopores) and Si–MWCNT electrodes (macropores), the volume change is significantly suppressed, resulting in stable electrodes with tunable mass loadings from 1.7 to 5.4 mg cm−2. When directly used as an anode, the Si–MWCNT film with a mass loading of 2.9 mg cm−2 exhibits a high specific capacity of 1556 mA h g−1 and an areal capacity of 4.5 mA h cm−2. Remarkably, when this freestanding anode is coupled with a commercial LiNi1/3Co1/3Mn1/3O2 (NCM) cathode, the full battery delivers a high gravimetric energy density of ∼484.7 W h kg−1. This study offers a promising and general route to design freestanding electrodes by percolating CNTs with PVD generated 2D porous nanoflakes and provides significant insights for developing high energy battery systems.

Quantitatively elucidating the reaction kinetics of Li–sulfur (Li–S) batteries is always crucial in optimizing cathode structures but challenging as well. Herein, we study and compare the reaction mechanism and kinetics of Li–S batteries via operando X-ray diffraction (XRD) and quantitative analysis based on several cathode structures. Operando XRD indicates that β-S8 has different nucleation orientations on MnO2 and carbon surfaces due to the different surface free energies. The quantitative analysis reveals that polysulfides encapsulated in MnO2 nanosheets result in fast Li2S and β-S8 nucleation in the discharge and charge processes, respectively. It also shows that open-hollow S@MnO2 exhibits faster S consumption and higher sulfur utilization than the solid core–shell S@MnO2 and carbon black/S. Our work provides deep insight into the reaction mechanism and kinetics of Li–S batteries and indicates that the cathode structures and host materials play critical roles in enhancing the reaction kinetics.

High-performance flexible lithium-ion batteries are leading candidates for power sources of wearable and foldable electronics. As a result, it is vital to design freestanding electrodes with high capacity and stability. Herein, we develop a novel strategy to significantly improve the performance of freestanding anodes by artificially introducing an ultrathin but robust interface based on polyacrylamide/gelatin gel with excellent mechanical durability and ionic conductivity. The artificial interface suppresses the formation of a thick solid electrolyte interface, facilitates charge transfer processes and strengthens the integrity of the electrode. Benefitting from these merits, our freestanding anode made of the nano/microstructured NiFe2O4–CNTs composite achieves a high capacity of 612 mA h g−1 based on the total mass of the electrode. The high-performance freestanding anode further enables a stable output capacity of 140 mA h g−1 over 1000 charge/discharge cycles for a full battery using commercial LiMn2O4 as the cathode material. Meanwhile, the excellent rate performance of the freestanding anode guarantees high energy output up to 255 W h kg−1 at a high power density of 12 000 W kg−1 for the full battery. Moreover, the intrinsic flexibility of the freestanding electrodes enables the fabrication of a flexible lithium-ion battery, which is highly stable even under harsh mechanical deformation. This work provides a new perspective to fabricate next-generation flexible batteries with high energy density and excellent stability, further advancing the development of foldable and wearable electronics toward practical applications.

Li–O2 batteries trigger worldwide interest as promising candidates for future energy supplies. One of the major challenges regarding current Li–O2 batteries is exploring highly efficient cathodes with sophisticated structures and compositions. Herein, highly dispersed metal (Pd) or oxide (RuO2) nanoparticles on ultra-polar carbon are synthesized and employed as cathode materials for Li–O2 batteries. The hierarchically porous structure of the carbon facilitates the oxygen diffusion and electrolyte impregnation and provides enough space to accommodate the discharge products. More importantly, the porous carbon with the ultra-polar surface serves as an efficient support for distinct dispersion of Pd or RuO2 nanoparticles which not only greatly enhances the catalytic activity but also eases side reactions by passivating the carbon defects. By virtue of the hierarchical structure associated with the extremely high dispersion of active particles, the battery performance is effectively enhanced by greatly prolonging the cycle life and significantly lowering the overvoltages especially for the charging process. The encouraging results suggest that such ultra-polar hierarchical carbon-based composites can be appealing materials for rechargeable Li–O2 batteries.

Engineered nanomembranes are of great interest not only for large-scale energy storage devices, but also for on-chip energy storage integrated microdevices (such as microbatteries, microsupercapacitors, on-chip capacitors, etc.) because of their large active surfaces for electrochemical reactions, shortened paths for fast ion diffusion, and easy engineering for microdevice applications. In addition, engineered nanomembranes provide a lab-on-chip electrochemical device platform for probing the correlations of electrode structure, electrical/ionic conductivity, and electrochemical kinetics with device performance. This review focuses on the recent progress in engineered nanomembranes including tubular nanomembranes and planar nanomembranes, with the aim to provide a systematic summary of their fabrication, modification, and energy storage applications in lithium-ion batteries, lithium-oxygen batteries, on-chip electrostatic capacitors and micro-supercapacitors. A comprehensive understanding of the relationship between engineered nanomembranes and electrochemical properties of lithium ion storage with engineered single-tube microbatteries is given, and the flexibility and transparency of micro-supercapacitors is also discussed. Remarks on challenges and perspectives related to engineered nanomembranes for the further development of energy storage applications conclude this review.

We propose an effective strategy to engineer a unique kind of porous carbon cuboid with tightly anchored cobalt/cobalt oxide nanoparticles (PCC–CoOx) that exhibit outstanding electrochemical performance for many key aspects of lithium-ion battery electrodes. The host carbon cuboid features an ultra-polar surface reflected by its high hydrophilicity and rich surface defects due to high heteroatom doping (N-/O-doping both higher than 10 atom%) as well as hierarchical pore systems. We loaded the porous carbon cuboid with cobalt/cobalt oxide nanoparticles through an impregnation process followed by calcination treatment. The resulting PCC–CoOx anode exhibits superior rate capability (195 mA h g−1 at 20 A g−1) and excellent cycling stability (580 mA h g−1 after 2000 cycles at 1 A g−1 with only 0.0067% capacity loss per cycle). Impressively, even after an ultra-long cycle life exceeding 10000 cycles at 5 A g−1, the battery can recover to 1050 mA h g−1 at 0.1 A g−1, perhaps the best performance demonstrated so far for lithium storage in cobalt oxide-based electrodes. This study provides a new perspective to engineer long-life, high-power metal oxide-based electrodes for lithium-ion batteries through controlling the surface chemistry of carbon host materials.

Luminescent nanoparticles (NPs) are deposited onto two dimensional (2D) pre-strained TiO2 nanomembranes by spin-coating. After rolling up the 2D differentially strained TiO2 nanomembranes into 3D microtube structures, the NPs are embedded within the tube windings. The embedded NPs serve as a light source for optical whispering-gallery-mode resonances under laser excitation, and therefore allow the TiO2 microtube to work as an active microcavity operating in emission mode. The spectral range of resonant modes can be tuned from the visible to the near infrared by embedding the proper NPs in the TiO2 tube wall. Rolled-up TiO2 microcavities combined with luminescent NPs could offer interesting opportunities in a variety of research fields, such as bio- and nanophotonics, optoelectronics, and optofluidics.

The search for new stable and efficient cathode materials for nonaqueous Li–O2 batteries has become an urgent task to satisfy the ever-growing needs for high capacity and high energy efficiency. To circumvent above issues, we have designed and synthesized isolated Au and Pd decorated MnOx nanomembranes, which act as bifunctional catalysts for Li–O2 batteries with a high specific capacity of 3200 mA h g−1 at 500 mA g−1 which is 9.8 and 3.2 times that of Super P and bare MnOx, respectively. In addition, with such novel structured catalysts, lithium ions, electrons and oxygen-containing intermediates can be rapidly transported, thus greatly improving the performance of Li–O2 batteries by significantly lowering the polarization and extending the cycle life to 120 times. The encouraging electrochemical property of such Au–Pd decorated MnOx nanomembranes leads to potential applications of the materials for high-performance Li–O2 batteries.

We demonstrate here a facile one-step hydrothermal synthesis to prepare molybdenum disulfide nanosheets decorated with gold nanoparticles (MoS2/AuNPs) for rechargeable Li–O2 batteries. The fabricated Li–O2 battery exhibits enhanced specific capacity and cycle efficiency, which are ascribed to the two-dimensional structure of MoS2/AuNP nanohybrids and the synergistic catalytic effects of both MoS2 nanosheets and AuNPs.

In this tutorial we review recent progress in the design and growth of epitaxial semiconductor nanostructures in lattice-mismatched material systems. We focus on the Ge on Si model system after pointing out the similarities to III-V and other growth systems qualitatively as well as quantitatively. During material deposition, the first layers of the epitaxial film wet the surface before the formation of strain-driven three-dimensional nanostructures. In particular, we stress that the supersaturation of the wetting layer (WL), whose relevance is often neglected, plays a key role in determining the nucleation and growth of nanodots (NDs), nanodot-molecules and nanowires (NWs). At elevated growth temperatures the Ge reservoir in the planar, supersaturated WL is abruptly consumed and generates NDs with highly homogeneous sizes - a process mainly driven by elastic energy minimization. Furthermore, the careful control of the supersaturated Ge layer allows us to obtain perfectly site-controlled, ordered NDs or ND-molecules on pit-patterned substrates for a broad range of pit-periods. At low growth temperatures subtle interplays between surface energies of dominant crystal facets in the system drive the material transfer from the supersaturated WL into the elongating NWs growing horizontally, dislocation- and catalyst-free on the substrate surface. Due to the similarities in the formation of nanostructures in different epitaxial semiconductor systems we expect that the observation of the novel growth phenomena described in this Tutorial Review for Ge/Si should be relevant for other lattice-mismatched heterostructure systems, too.

Amorphous SnO2 nanomembranes as anodes for lithium ion batteries demonstrate a long cycling life of 1000 cycles at 1600 mA g(-1) with a high reversible capacity of 854 mA h g(-1) and high rate capability up to 40 A g(-1). The superior performance is because of the structural features of the amorphous SnO2 nanomembranes. The nanoscale thickness provides considerably reduced diffusion paths for Li(+). The amorphous structure can accommodate the strain of lithiation/delithiation, especially during the initial lithiation. More importantly, the mechanical feature of deformation can buffer the strain of repeated lithiation/delithiation, thus putting off pulverization. In addition, the two-dimensional transport pathways in between nanomembranes make the pseudo-capacitance more prominent. The encouraging results demonstrate the significant potential of nanomembranes for high power batteries.

Artificial microvasculature, particularly as part of the blood-brain barrier, has a high benefit for pharmacological drug discovery and uptake regulation. We demonstrate the fabrication of tubular structures with patterns of holes, which are capable of mimicking microvasculatures. By using photolithography, the dimensions of the cylindrical scaffolds can be precisely tuned as well as the alignment and size of holes. Overlapping holes can be tailored to create diverse three-dimensional configurations, for example, periodic nanoscaled apertures. The porous tubes, which can be made from diverse materials for differential functionalization, are biocompatible and can be modified to be biodegradable in the culture medium. As a proof of concept, endothelial cells (ECs) as well as astrocytes were cultured on these scaffolds. They form monolayers along the scaffolds, are guided by the array of holes and express tight junctions. Nanoscaled filaments of cells on these scaffolds were visualized by scanning electron microscopy (SEM). This work provides the basic concept mainly for an in vitro model of microvasculature which could also be possibly implanted in vivo due to its biodegradability.

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence., The development of artificial micromotors is one of the greatest challenges of modern nanotechnology. Even though many kinds of motors have been published in recent times, systematic studies on the influence of components of the fuel solution are widely missing. Therefore, the autonomous movement of Pt-microtubes and Pt-covered silica particles is comparatively observed in the presence and absence of surfactants in the medium. One representative of each of the three main surfactant classes-anionic (sodium dodecyl sulfate, SDS), cationic (benzalkonium chloride, BACl) and non-ionic (Triton X)-has been chosen and studied., This research was partially supported by grant from Ministerio de Economía y Competitividad; MINECO (grant number MAT2012-38318-C03-02) and the ERC grant “Lab-in-a-tube and Nanorobotics biosensors” (grant number #311529).

For transportation of molecules or biological cells using artificial motors, the control over their motion, i.e. direction and speed of transfer, is important. Here, we demonstrate that modification of the velocity and orientation of a magnetic Janus particle can be efficiently controlled by tuning the strength of an applied homogeneous magnetic field. Interestingly, by keeping the same orientation of the magnetic field but changing its magnitude not only the velocity of capped particles can be altered but even their direction of motion can be reversed. We put forth a simple qualitative model, which allows us to explain this intriguing observation.

Biocompatible, multifunctional large arrays of transparent SiO/SiO2 microtubes are fabricated by rolled-up nanotech. The outer tubular diameter as a function of thicknesses of SiO and SiO2 has been systematically studied and the roll-up parameters have been optimized to deterministically achieve a yield of nearly 100%. A macroscopic continuum mechanical model is in good agreement with the experimental data. The relative ease in functionalization of the “glass” microtubes with different biomaterials renders rolled-up nanotech an excellent option for various on- and off-chip applications, including optofluidic sensors, micro-engines and pre-patterned 3D scaffolds for cell culturing.

Transparent oxide rolled-up microtube arrays were constructed on Si substrates by the deposition of a pre-stressed oxide layer on a patterned photoresist sacrificial layer and the subsequent removal of this sacrificial layer. These microtubes as well as their arrays can be well positioned onto a chip for further applications, while their dimensions (e.g. length, diameter and wall thickness) are controlled by tunable parameters of the fabrication process. Due to the unique tubular structure and optical transparency, such rolled-up microtubes can serve as well-defined two-dimensionally (2D) confined cell culture scaffolds. In our experiments, yeast cells exhibit different growth behaviors (i.e. their arrangement) in microtubes with varied diameters. In an extremely small microtube the yeast cell becomes highly elongated during growth but still survives. Detailed investigations on the behavior of individual yeast cells in a single microtube are carried out in situ to elucidate the mechanical interaction between microtubes and the 2D confined cells. The confinement of tubular channels causes the rotation of cell pairs, which is more pronounced in smaller microtubes, leading to different cellular assemblies. Our work demonstrates good capability of rolled-up microtubes for manipulating individual and definite cells, which promises high potential in lab-on-a-chip applications, for example as a bio-analytic system for individual cells if integrated with sensor functionalities.

Moving towards the realization of ultra-compact diagnostic systems, we demonstrate the design, realization and characterization of rolled-up nanomembrane-based chemical sensing elements operating at room temperature. The tube-shaped devices with a final diameter of ∼15 μm rely on a fabrication process which combines top-down and bottom-up approaches and is compatible with standard processing technologies. Arrays of sensors are created in parallel on-a-chip, consequently, the integration of such elements into lab-in-a-tube devices as sensing units certainly seems feasible. The sensing properties of the devices are created by the selective incorporation of thin organic active layers in the inner wall of the microtubes. While the sensitivity towards volatile organic compounds is observed to be similar to previously reported sensors, indicating that the integration of the organic layer is efficiently achieved, the occupied footprint area of the tube-shaped devices is at least one order of magnitude smaller than its planar counterpart. This particular feature makes this procedure an attractive pathway to condense sensing elements for ultra-compact devices.

Sulfphur containing compounds, such as extracellular thiols (glutathione, cysteine, methionine) or organic solvents (DMSO) can cripple drastically the motion of Pt catalytic microjets even at very small concentrations., Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing –SH, –SSR, and –SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.

In this work, we introduce a new concept to fabricate on chip, all solid-state and flexible micro-supercapacitors based on MnOx/Au multilayers, which are compatible with current microelectronics. The micro-supercapacitor exhibits a maximum energy density of 1.75 mW h cm−3 and a maximum power density of 3.44 W cm−3, which are both much higher than the values obtained for other solid-state supercapacitors. At a scan rate of 1 V s−1, a volumetric capacitance of 32.8 F cm−3 is obtained for MnOx/Au multilayer electrodes, which is much higher than the bare MnOx electrode. Electrochemical impedance spectroscopy (EIS) and evolution complex capacitance confirm that the electrical conductivity of MnOx is improved due to the incorporation of gold, and a low relaxation time constant around 5 ms is observed. The MnOx/Au multilayer micro-supercapacitor also shows good long-term cycling stability, with a capacitance retention rate of 74.1% after a large cycling number of 15000 times. Compared with other supercapacitors, which are not portable and are relatively bulky, the device demonstrated here allows fast and reliable applications in a portable and smart fashion. Furthermore, the nature of the process allows the micro-supercapacitor to be integrated with other micro-devices, to meet the need for micro-scale energy storage.

Biology widely employs catalytic reactions to power biomotors and cells. These dynamic entities can self-organize into swarms or self-assemble into functional micro- or nanostructures. Synthetic micro-/nanojet engines and nanomotors, driven by catalytic reactions, can move with high power and perform multiple tasks. Collective behavior of these microengines has recently been observed which includes swarming activities and the formation of multiconstituent entities. This feature article discusses recent developments, presents new discoveries on collective motion of self-propelled microjet engines and suggests next steps to undertake in the field of collective micromachines.

Compact rolled-up Co-Cu nanomembranes of high quality with different numbers of windings are realized by strain engineering. A profound analysis of magnetoresistance (MR) is performed for tubes with a single winding and a varied number of Co-Cu bilayers in the stack. Rolled-up nanomembranes with up to 12 Co-Cu bilayers are successfully fabricated by tailoring the strain state of the Cr bottom layer. By carrying out an angular dependent study, we ruled out the contribution from anisotropic MR and confirm that rolled-up Co-Cu multilayers exhibit giant magnetoresistance (GMR). No significant difference of MR is found for a single wound tube compared with planar devices. In contrast, MR in tubes with multiple windings is increased at low deposition rates of the Cr bottom layer, whereas the effect is not observable at higher rates, suggesting that interface roughness plays an important role in determining the GMR effect of the rolled-up nanomembranes. Furthermore, besides a linear increase of the MR with the number of windings, the self-rolling of nanomembranes substantially reduces the device footprint area.

We present a conceptually new approach for the detection of magnetic objects flowing through a fluidic channel. We produce an elastic and stretchable magnetic sensor and wrap it around capillary tubing. Thus, the stray fields induced by the flowing magnetic objects can be detected virtually in all directions (isotropic sensitivity), which is unique for elastic sensors when compared to their rigid planar counterparts.

The fabrication of tubular rolled-up optofluidic ring resonators (RU-OFRRs) based on glass (SiO(2)) material with high quality factors is reported. A novel methodology combining lab-on-a-chip fabrication methods and rolled-up nanotech is presented for the fabrication of fully integrated tubular optofluidic sensors. The microfluidic integration of several RU-OFRRs on one chip is solved by enclosing the microtubes with a patterned robust SU-8 polymeric matrix. A viewport on each microtube enables exact excitation and monitoring of whispering gallery modes with a photoluminescence spectroscopy system under constant ambient conditions, while exchanging the content of the RU-OFRR with liquids of different refractive indices. The refractrometric sensor capabilities are investigated regarding signal stability, sensitivity and reliability. The sensitivity of the integrated RU-OFRR, which is the response of the modes to the change in refractive index of the liquid, is up to 880 nm/refractive index units (RIU).

A review of present and future on-chip rolled-up devices, which can be used to develop lab-in-a-tube total analysis systems, is presented. Lab-in-a-tube is the integration of numerous rolled-up components into a single device constituting a microsystem of hundreds/thousands of independent units on a chip, each individually capable of sorting, detecting and analyzing singular organisms. Such a system allows for a scale-down of biosensing systems, while at the same time increasing the data collection through a large, smart array of individual biosensors. A close look at these ultracompact components which have been developed over the past decade is given. Methods for the capture of biomaterial are laid out and progress of cell culturing in three-dimensional scaffolding is detailed. Rolled-up optical sensors based on photoluminescence, optomechanics, optofluidics and metamaterials are presented. Magnetic sensors are introduced as well as electrical components including heating, energy storage and resistor devices.

A method which eliminates the need for a sacrificial layer in rolled-up systems is put forth. Instead, the self-assembly relies solely on the delamination of a patterned polymer layer. This polymer layer can contain any of a number of inorganic active nanomembranes which exhibit a variety of material properties for numerous system functionalities.