In vivo imaging and actuation of a swarm of magnetic helical microswimmers by external magnetic fields (less than 10 mT) in deep tissue is demonstrated for the first time. This constitutes a major ...milestone in the field, yielding a generation of micrometer‐scale transporters with numerous applications in biomedicine including synthetic biology, assisted fertilization, and drug/gene delivery.
A simple and general fabrication method for helical swimming micromachines by direct laser writing and e‐beam evaporation is demonstrated. The magnetic helical devices exhibit varying magnetic shape ...anisotropy, yet always generate corkscrew motion using a rotating magnetic field. They also exhibit good swimming performance and are capable of pick‐and‐place micromanipulation in 3D. Cytotoxicity of the devices was investigated using mouse myoblasts.
Functional compound micromachines are fabricated by a design methodology using 3D direct laser writing and selective physical vapor deposition of magnetic materials. Microtransporters with a ...wirelessly controlled Archimedes screw pumping mechanism are engineered. Spatiotemporally controlled collection, transport, and delivery of micro particles, as well as magnetic nanohelices inside microfluidic channels are demonstrated.
Magnetic Helical Micromachines Peyer, Kathrin E.; Tottori, Soichiro; Qiu, Famin ...
Chemistry : a European journal,
January 2, 2013, Letnik:
19, Številka:
1
Journal Article
Recenzirano
Helical microrobots have the potential to be used in a variety of application areas, such as in medical procedures, cell biology, or lab‐on‐a‐chip. They are powered and steered wirelessly using ...low‐strength rotating magnetic fields. The helical shape of the device allows propulsion through numerous types of materials and fluids, from tissue to different types of bodily fluids. Helical propulsion is suitable for pipe flow conditions or for 3D swimming in open fluidic environments.
Helices, screws or twists transform rotational motion into translations in soft tissue or fluidic environments. The actuation occurs wirelessly through low‐strength rotating magnetic fields. These swimming microrobots can be used for micro‐object or microfluidic manipulation tasks or as transport platforms for targeted delivery in medical applications.
A series of V(2)O(5)/TiO(2)-carbon nanotube (CNT) catalysts were synthesized by sol-gel method, and their activities for NO(X) removal were compared. A catalytic promotional effect was observed by ...adding CNTs to V(2)O(5)/TiO(2). The catalyst V(2)O(5)/TiO(2)-CNTs (10wt.%) showed an NO(X) removal efficiency of 89% at 300°C under a GHSV of 22,500h(-1). Based on X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, NH(3)-temperature-programmed desorption, temperature-programmed reduction, Brunauer-Emmett-Teller surface area measurements, differential scanning calorimetry, and thermogravimetric analysis, the increased acidity and reducibility, which could promote NH(3) adsorption and oxidation of NO to NO(2), respectively, contributed to this promotion.
Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub-micrometer precision under low-strength rotating magnetic fields (<10 mT). Since magnetic fields with ...low strengths are harmless to cells and tissues, magnetic helical micro/nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.
Catalysts V2O5/TiO2–carbon nanotubes (CNTs) were prepared by hydrothermal method and their activity for catalytic oxidation of chlorobenzene (CB) was studied. A CB conversion efficiency of 45% with a ...CO2 selectivity of 80% was achieved over V2O5 (1.2 wt %)/TiO2–CNTs(8.6 wt %) at a temperature as low as 200 °C. It also has the highest removal efficiency of 95% at 300 °C. From the analysis of XRD, SEM, TEM, and TPR, the low-temperature activity of V2O5/TiO2–CNTs could be ascribed to the high S BET, good dispersion of V2O5, and the possible adsorption of CB by free surface of CNTs.
Manipulation and transport of microscale objects in 3D with high spatiotemporal resolution require precise control over the applied forces. We report a strategy that uses specially engineered ...microbars having engagement points and multiple helical microcarriers that can apply reversible loads onto these holders. The helical microcarriers are actuated by externally generated, low strength magnetic fields. By optimizing the design of helical structures for precise manipulation, we fabricated microcarriers that swim with little wobbling even at low rotating frequencies. The cooperation of microcarriers generates higher propulsive forces while application of forces at multiple locations results in motion control with multiple degrees of freedom (DOF). The microbar loaded with multiple microcarriers can be employed as a single mobile device for the realization of higher order manipulation tasks.
Herein, we assess the functionality of magnetic helical microswimmers as basic tools for the manipulation of soft materials, including microdroplets and single cells. Their ability to perform a range ...of unit operations is evaluated and the operational challenges associated with their use are established. In addition, we also report on interactions observed between the head of such helical swimmers and the boundaries of droplets and cells and discuss the possibilities of assembling an artificial swimming microorganism or a motorized cell.
MnO
x
/Al
2
O
3
-carbon nanotubes (CNTs) composites prepared by hydrothermal method were characterized by XRD, SEM, TEM, TGA, BET, XPS and H
2
-TPR. Catalytic oxidation of chlorobenzene (CB) was ...conducted over the composites under gas hourly space velocity (GHSV) of 36000 h
−1
and CB concentration of 2800 ppmv. For the catalyst with approximately 25 wt% CNTs and 10 at.% Mn, CB removal efficiencies reached up to 83.3 and 97.7% at 150 and 300 °C, respectively. Moreover, no Cl species was detected over the used MnO
x
/Al
2
O
3
-CNTs catalyst implying that the release of chlorine element from the catalyst surface was facilitated by CNTs introduction.
Graphical Abstract
MnO
x
/Al
2
O
3
-carbon nanotubes (CNTs) composites were prepared by hydrothermal method. Catalytic oxidation of chlorobenzene (CB) was conducted over the composites in a continuous fixed bed flow reactor. CB removal efficiencies at different temperatures were obtained over various catalysts with different CNTs concentrations under a gas space velocity of 36000 h
−1
and CB concentration of 2800 ppmv. For the catalyst Mn/Al-C-2 with approximately 25 wt% CNTs and 10 at.% Mn, CB removal efficiencies of 83.3% at 150 °C and 97.7% at 300 °C were obtained. Our results suggest that the introduction of CNTs could significantly promote the catalytic oxidation of CB in low temperature region.
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