Near-Infrared Light-Steered Graphene Aerogel Micromotor with High Speed and Precise Navigation for Active Transport and Microassembly

Abstract

Fuel-free light-driven micromotors have attracted increasing attention since the advantages of reversible, noninvasive, and remote maneuver are on demand with excellent spatial and temporal resolution. However, they suffer from a challenging bottleneck of the rather modest motion speed, which hinders their applications, needing to overcome the water flow movement in environmental water. Herein, we demonstrate a near-infrared (NIR) light-steered, precise navigation-controlled micromotor based on a reduced graphene oxide aerogel microsphere (RGOAM), which possesses an isotropic structure and is easily prepared by a one-step electrospray approach other than conventional light-propelled micromotors with the Janus structure. Benefiting from the ultralight weight of the aerogel and lesser fluid resistance on the water surface, the RGOAM motors show a higher motion speed (up to 17.60 mm/s) than that in the published literature, letting it overcome counterflow. Taking advantage of the photothermal conversion capacity of the RGOAM under an asymmetric light field, it is capable of moving both on the water driven by the Marangoni effect and under the water via light-manipulated density change. The motion direction and speed on water as well as the “start/stop” state can be precisely steered by NIR light even in a complicated maze. Due to its strong adsorption and loading capacity, the RGOAM can be applied for active loading-transport-release of dyes on demand as well as micropart assembling and shaping. Our work provides a strategy to achieve high speed, precise navigation control, and functional extensibility simultaneously for micromotors, which may offer considerable promise for the broad biomedical and environmental applications.

The Encoding of Light‐Driven Micro/Nanorobots: from Single to Swarming Systems

“…However, the UV light is not preferred for biological applications due to the potential damage to tissue and insufficient penetration depth, which encouraged the development of LMNRs powered by visible and NIR light via self-electrophoretic or photothermal effects (Figure 4b-d). [20,23,[63][64][65][66][67] Notably, the LMNR made of core-shell p-n junction silicon nanowire operate under both visible and NIR illuminations. [20] By engineering the photonic structure and the optical resonance inside this .…”

External Field‐Driven Untethered Microrobots for Targeted Cargo Delivery

“…Magnetic-driven microswimmers Acoustic-driven microstructures Main body component ♦ Emulsification [37,97] ♦ Drop-casting [79a] ♦ LbL self-assembly [38,79e] ♦ Electrospray [39] ♦ Chemical synthesis [12,33] ♦ Femtosecond laser [98] ♦ TPP/DLW/3D laser lithography [13,18b,31,59,95a] ♦ 3D template assisted electrodeposition [78a] ♦ UV polymerization [22b,24,74c,79b] ♦ Biotemplating synthesis [99] ♦ Microfluidic spinning technology [23a,70c] ♦ Laser etching [32,82a] ♦ GLAD [30,69g] ♦ Ion etching + ♦ Atomic layer deposition [88] ♦ Hydrophobic treatment [100] Functional component ♦ Sputter coating system [35e-g,37,69a] ♦ E-beam evaporation [79c,81c,e] ♦ Physical vapor deposition [80b] ♦ Thermal evaporation [81b] ♦ Dip-coating [19b] ♦ Embedded inside scaffold materials [23a,73,101] plenty of inspiration, such as the spiral motion of Escherichia coli. E. coli consists of a head and a spiral tail and can move like a screw even in a viscous environment where viscous forces play a dominant role.…”

“…Under the irradiation of NIR light, the temperature of the aqueous solution around the photothermal material rises, while the temperature on the other side of the micromotors is relatively low, thus creating a local temperature gradient and generating thermophoretic force that propels the micromotors forward. [39] The other kind of photocatalytic materials is mainly photodecomposable materials, such as silver halide, among which AgCl is widely selected in the literature. Herein, AgCl is used as an example to explain the self-diffusiophoresis mechanism.…”

Superfast Active Droplets as Micromotors for Locomotion of Passive Droplets and Intensification of Mixing

“…One of the crucial applications of microrobots is cargo transport. − Herein, both passive solid particles and droplets can be transported. The majority of studies on microscale cargo delivery have been based on attaching cargos to an active swimmer.…”