Systems capable of precise motion in the vasculature can offer exciting possibilities for applications in targeted therapeutics and non-invasive surgery. So far, the majority of the work analysed ...propulsion in a two-dimensional setting with limited controllability near boundaries. Here we show bio-inspired rolling motion by introducing superparamagnetic particles in magnetic and acoustic fields, inspired by a neutrophil rolling on a wall. The particles self-assemble due to dipole-dipole interaction in the presence of a rotating magnetic field. The aggregate migrates towards the wall of the channel due to the radiation force of an acoustic field. By combining both fields, we achieved a rolling-type motion along the boundaries. The use of both acoustic and magnetic fields has matured in clinical settings. The combination of both fields is capable of overcoming the limitations encountered by single actuation techniques. We believe our method will have far-reaching implications in targeted therapeutics.Devising effective swimming and propulsion strategies in microenvironments is attractive for drug delivery applications. Here Ahmed et al. demonstrate a micropropulsion strategy in which a combination of magnetic and acoustic fields is used to assemble and propel colloidal particles along channel walls.
Superparamagnetic nanoparticles and a functional, degradable polymer matrix based on poly(ethylene glycol) are combined to enable fully degradable magnetic microdevices for minimally invasive ...biomedical applications. A bioinspired helical microrobot platform mimicking Escherichia coli bacteria is fabricated and actuated using weak rotating magnetic fields. Locomotion based on corkscrew propulsion, targeted drug delivery, and low‐degradation‐product cytotoxicity are demonstrated.
We performed whole-genome sequencing (WGS) of 208 genomes from 53 families affected by simplex autism. For the majority of these families, no copy-number variant (CNV) or candidate de novo ...gene-disruptive single-nucleotide variant (SNV) had been detected by microarray or whole-exome sequencing (WES). We integrated multiple CNV and SNV analyses and extensive experimental validation to identify additional candidate mutations in eight families. We report that compared to control individuals, probands showed a significant (p = 0.03) enrichment of de novo and private disruptive mutations within fetal CNS DNase I hypersensitive sites (i.e., putative regulatory regions). This effect was only observed within 50 kb of genes that have been previously associated with autism risk, including genes where dosage sensitivity has already been established by recurrent disruptive de novo protein-coding mutations (ARID1B, SCN2A, NR3C2, PRKCA, and DSCAM). In addition, we provide evidence of gene-disruptive CNVs (in DISC1, WNT7A, RBFOX1, and MBD5), as well as smaller de novo CNVs and exon-specific SNVs missed by exome sequencing in neurodevelopmental genes (e.g., CANX, SAE1, and PIK3CA). Our results suggest that the detection of smaller, often multiple CNVs affecting putative regulatory elements might help explain additional risk of simplex autism.
Mobile micro‐ and nanorobots are proposed for future biomedical applications, such as diagnostics and targeted delivery. For their translation to clinical practice, biocompatibility and ...biodegradability of micro‐ and nanorobots are required aspects. The fabrication of small‐scale robots with non‐cytotoxic biodegradable soft components will allow for enhanced device assimilation, optimal tissue interaction and minimized immune reactions. The 3D microfabrication of biodegradable soft helical microswimmers via two‐photon polymerization of the non‐toxic photocrosslinkable hydrogel gelatin methacryloyl (GelMA) is reported. GelMA microswimmers are fabricated with user‐defined geometry and rendered magnetically responsive by decorating their surface with magnetic nanoparticles. In contrast to previous rigid helical microrobots, the soft helical microswimmers can corkscrew above the step‐out frequency with relatively high values of forward velocity, suggesting an unprecedented self‐adaptive behavior. Cytotoxicity assays show the toxicity of GelMA is at least three orders of magnitude lower than that of poly(ethyleneglycol) diacrylates, which are widely used for fabricating hydrogel‐based microswimmers. GelMA microswimmers are fully degradable by collagenases. Furthermore, they support cell attachment and growth, and are gradually digested by cell‐released enzymes during culture. These non‐cytotoxic biodegradable hydrogel microswimmers will greatly expand their applications in medicine by eliminating the concerns of retrieving microrobots after fulfilling tasks in body.
Biodegradable soft helical microswimmers are successfully developed based on two‐photon photopolymerization of a gelatin derivative, GelMA. By decorating their surface with magnetic nanoparticles, these microswimmers can be manipulated by magnetic field. Because of the proteolytic cleavage of peptide domains in gelatin, microswimmers made of GelMA can be fully degraded by cell‐secreted proteases.
Robotics is a forward-looking discipline. Attention is focused on identifying the next grand challenges. In an applied field such as medical robotics, however, it is important to plan the future ...based on a clear understanding of what the research community has recently accomplished and where this work stands with respect to clinical needs and commercialization. This Review article identifies and analyzes the eight key research themes in medical robotics over the past decade. These thematic areas were identified using search criteria that identified the most highly cited papers of the decade. Our goal for this Review article is to provide an accessible way for readers to quickly appreciate some of the most exciting accomplishments in medical robotics over the past decade; for this reason, we have focused only on a small number of seminal papers in each thematic area. We hope that this article serves to foster an entrepreneurial spirit in researchers to reduce the widening gap between research and translation.
Soft Micro- and Nanorobotics Hu, Chengzhi; Pané, Salvador; Nelson, Bradley J
Annual review of control, robotics, and autonomous systems,
05/2018, Letnik:
1, Številka:
1
Journal Article
Recenzirano
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Micro- and nanorobots can perform a number of tasks at small scales, such as minimally invasive diagnostics, targeted drug delivery, and localized surgery. During the past decade, the field has been ...transformed in many ways, one of the most significant being a transition from hard and rigid micro- and nanostructures to soft and flexible architectures. Inspired by the dynamics of flexible microorganisms, researchers have focused on developing miniaturized soft components such as actuators, sensors, hinges, joints, and reservoirs to create soft micro- and nanoswimmers. The use of organic structures such as polymers and supramolecular ensembles as functional components has brought more complex features to these devices, such as advanced locomotion strategies and stimulus-triggered shape transformations, as well as other capabilities. A variety of microorganisms and contractile mammalian cells have also been utilized as microengines and integrated with functional synthetic materials, producing bending or deformation of the functional materials to initiate motion. In this review, we consider several types of soft micro- and nanorobots in terms of their architecture and design, and we describe their locomotion mechanisms and applications.
Magnetic control of continuum devices Edelmann, Janis; Petruska, Andrew J; Nelson, Bradley J
The International journal of robotics research,
01/2017, Letnik:
36, Številka:
1
Journal Article
Recenzirano
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In this paper we apply Cosserat rod theory to catheters with permanent magnetic components that are subject to spatially varying magnetic fields. The resulting model formulation captures the ...magnetically coupled catheter behavior and provides numerical solutions for rod equilibrium configurations in real-time. The model is general, covering cases with different catheter geometries, multiple magnetic components, and various boundary constraints. The necessary Jacobians for quasi-static, closed-loop control using an electromagnetic coil system and a motorized advancer are derived and incorporated into a visual-feedback controller. We address the issue of solution bifurcations caused by the magnetic field by proposing an additional, stabilizing control method that makes use of system redundancies. We demonstrate the effectiveness of the model by performing 3D tip-position trajectories with root-mean-square distance errors of 2.7 mm in open-loop, 0.30 mm in closed-loop, and 0.42 mm in stabilizing closed-loop modes. The stabilizing controller achieved on average a factor of 1.6 increase in the restoring wrenches for the least stable direction.
Minimally invasive neurosurgery does not require large incisions and openings in the skull to access the desired brain region, which often results in a faster recovery with fewer complications than ...traditional open neurosurgery. For disorders treated by the implantation of neurostimulators and thermocoagulation probes, current procedures incorporate a straight rigid needle, which restricts surgical trajectories and limits the number of possible targets and degrees of freedom at the respective target. A steerable needle with a flexible body could overcome these limitations. In this paper, we present a flexible needle steering system with magnetic and fluoroscopic guidance for neurosurgical procedures. A permanent magnet at the proximal end of a flexible needle is steered by an external magnetic field, and the resultant tip-deflection angle bends the flexible body like a bevel-tip needle. We implemented a kinematic model for the magnetic needle derived from a nonholonomic bicycle model and a closed-loop control strategy with feed-forward and feed-back components using a chained-form transformation. The proposed needle steering method was investigated through in vitro and ex vivo experiments.
Shape-morphing systems, which can perform complex tasks through morphological transformations, are of great interest for future applications in minimally invasive medicine
, soft robotics
, active ...metamaterials
and smart surfaces
. With current fabrication methods, shape-morphing configurations have been embedded into structural design by, for example, spatial distribution of heterogeneous materials
, which cannot be altered once fabricated. The systems are therefore restricted to a single type of transformation that is predetermined by their geometry. Here we develop a strategy to encode multiple shape-morphing instructions into a micromachine by programming the magnetic configurations of arrays of single-domain nanomagnets on connected panels. This programming is achieved by applying a specific sequence of magnetic fields to nanomagnets with suitably tailored switching fields, and results in specific shape transformations of the customized micromachines under an applied magnetic field. Using this concept, we have built an assembly of modular units that can be programmed to morph into letters of the alphabet, and we have constructed a microscale 'bird' capable of complex behaviours, including 'flapping', 'hovering', 'turning' and 'side-slipping'. This establishes a route for the creation of future intelligent microsystems that are reconfigurable and reprogrammable in situ, and that can therefore adapt to complex situations.
An FeGa@P(VDF‐TrFE) wire‐shaped magnetoelectric nanorobot is designed and fabricated to demonstrate a proof‐of‐concept integrated device, which features wireless locomotion and on‐site triggered ...therapeutics with a single external power source (i.e., a magnetic field). The device can be precisely steered toward a targeted location wirelessly by rotating magnetic fields and perform on‐demand magnetoelectrically assisted drug release to kill cancer cells.
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