ABSTRACT Semiconducting properties of nanoparticle coating on liquid metal marbles can present op... more ABSTRACT Semiconducting properties of nanoparticle coating on liquid metal marbles can present opportunities for an additional dimension of control on these soft objects with functional surfaces in aqueous environments. We show the unique differences in the electrochemical actuation mechanisms of liquid metal marbles with n- and p-type semiconducting nanomaterial coating. A systematic study on such liquid metal marbles shows voltage dependent nanoparticle cluster formation and morphological changes of the liquid metal core during electrochemical actuations and these observations are unique to p-type nanomaterial coated liquid metal marbles.
ABSTRACT Chaotic advection plays an important role in microplatforms for a variety of application... more ABSTRACT Chaotic advection plays an important role in microplatforms for a variety of applications. Currently used mechanisms for inducing chaotic advection in small scale, however, are limited by their complicated fabrication processes and relatively high power consumption. Here, a soft actuator is reported which utilizes a droplet of Galinstan liquid metal to induce harmonic Marangoni flow at the surface of liquid metal when activated by a sinusoidal signal. This liquid metal actuator has no rigid parts and employs continuous electrowetting effect to induce chaotic advection with exceptionally low power consumption. The theory behind the operation of this actuator is developed and validated via a series of experiments. The presented actuator can be readily integrated into other microfluidic components for a wide range of applications.
Quasi-two-dimensional (quasi-2D) molybdenum disulfide (MoS 2 ) is a photoluminescence (PL) materi... more Quasi-two-dimensional (quasi-2D) molybdenum disulfide (MoS 2 ) is a photoluminescence (PL) material with unique properties. The recent demonstration of its PL, controlled by the intercalation of positive ions, can lead to many opportunities for employing this quasi-2D material in ion-related biological applications. Here, we present two representative models of biological systems that incorporate the ion-controlled PL of quasi-2D MoS 2 nanoflakes. The ion exchange behaviors of these two models are investigated to reveal enzymatic activities and cell viabilities. While the ion intercalation of MoS 2 in enzymatic activities is enabled via an external applied voltage, the intercalation of ions in cell viability investigations occurs in the presence of the intrinsic cell membrane potential.
An improved method for electrochemical deposition (ED) of a novel precursor (peripheral carbazole... more An improved method for electrochemical deposition (ED) of a novel precursor (peripheral carbazole substituted 9,9 ′ -spirobifluorene (TCPC)) for fabricating highly efficient luminescent films and devices has been developed. Electrochemical deposition often leaves residual charged ion species within the film. These species can negatively impact the performance of these films in OLED applications. The amount of residual charged species in the films can be reduced by controlling the oxidation and reduction potentials, by using electrolytes with different counter anions, and by washing with solvents. An optimized ED process showed a significant decrease in the doping level; up to 0.07% in ED film. The films prepared under a scan potential range from 0.85 to −0.8 V, using TBAAsF 6 as the supporting electrolyte, and washed with solvent mixtures of acetonitrile and CH 2 Cl 2 (V/V = 2/3) demonstrated excellent device performance. Light-emitting devices fabricated by electrochemical deposition achieved deep blue emission (x, y) = (0.16, 0.06) in CIE coordinates. High luminance efficiencies of 2.3 cd A −1 were achieved for single-layer device; luminescence efficiencies of 4.4 cd A −1 were achieved for a double-layer device. Finally, the problem that ED films usually exhibit low electroluminescent efficiency is solved.
ABSTRACT An oligomer of polyfluorene, ter(9,9, 9″,9″-bihexyl-9′,9′-diphenyl)fluorenes (THPF), is ... more ABSTRACT An oligomer of polyfluorene, ter(9,9, 9″,9″-bihexyl-9′,9′-diphenyl)fluorenes (THPF), is used as a blue-emitting material to achieve efficient pure blue electroluminescence. Based on a 4,4′,4″-tri(N-carbazolyl)-triphenylamine hole-transporting layer, a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline hole-blocking layer, an (8-hydroxyquinoline) aluminum electron-transporting layer, and a LiF/Al cathode, the device has two emission peaks at 404 and 424 nm, chromaticity coordinates at (0.18, 0.09), and a maximum efficiency of 1.27 cd/A. By using a submonolayer of 5,6,11,12-tetraphenylnaphthacene as a carrier detector, we demonstrate that THPF functions well as an electron-transporting layer, similar to Alq.
On page 144, Kourosh Kalantar-zadeh, Arnan Mitchell, and co-workers introduce liquid metal marble... more On page 144, Kourosh Kalantar-zadeh, Arnan Mitchell, and co-workers introduce liquid metal marbles by encapsulating droplets of liquid metal in micro/nanoparticles that are insulating or semiconducting. The physical properties of the liquid metal marbles are investigated. The ability to form active electronic junctions using liquid metal marbles and its use as a highly sensitive, electrochemical-based, heavy metal ion sensor is demonstrated.
Abstract Liquid metal marbles that are droplets of liquid metal encapsulated by micro-or nanopart... more Abstract Liquid metal marbles that are droplets of liquid metal encapsulated by micro-or nanoparticles are introduced. Droplets of galinstan liquid metal are coated with insulators (including Teflon and silica) and semiconductors (including WO 3, TiO 2, MoO 3, In 2 O 3 and carbon nanotubes) by rolling over a powder bed and also by submerging in colloidal suspensions. It is shown that these marbles can be split and merged, can be suspended on water, and are even stable when moving under the force of gravity and impacting a flat ...
ABSTRACT Semiconducting properties of nanoparticle coating on liquid metal marbles can present op... more ABSTRACT Semiconducting properties of nanoparticle coating on liquid metal marbles can present opportunities for an additional dimension of control on these soft objects with functional surfaces in aqueous environments. We show the unique differences in the electrochemical actuation mechanisms of liquid metal marbles with n- and p-type semiconducting nanomaterial coating. A systematic study on such liquid metal marbles shows voltage dependent nanoparticle cluster formation and morphological changes of the liquid metal core during electrochemical actuations and these observations are unique to p-type nanomaterial coated liquid metal marbles.
ABSTRACT Chaotic advection plays an important role in microplatforms for a variety of application... more ABSTRACT Chaotic advection plays an important role in microplatforms for a variety of applications. Currently used mechanisms for inducing chaotic advection in small scale, however, are limited by their complicated fabrication processes and relatively high power consumption. Here, a soft actuator is reported which utilizes a droplet of Galinstan liquid metal to induce harmonic Marangoni flow at the surface of liquid metal when activated by a sinusoidal signal. This liquid metal actuator has no rigid parts and employs continuous electrowetting effect to induce chaotic advection with exceptionally low power consumption. The theory behind the operation of this actuator is developed and validated via a series of experiments. The presented actuator can be readily integrated into other microfluidic components for a wide range of applications.
Quasi-two-dimensional (quasi-2D) molybdenum disulfide (MoS 2 ) is a photoluminescence (PL) materi... more Quasi-two-dimensional (quasi-2D) molybdenum disulfide (MoS 2 ) is a photoluminescence (PL) material with unique properties. The recent demonstration of its PL, controlled by the intercalation of positive ions, can lead to many opportunities for employing this quasi-2D material in ion-related biological applications. Here, we present two representative models of biological systems that incorporate the ion-controlled PL of quasi-2D MoS 2 nanoflakes. The ion exchange behaviors of these two models are investigated to reveal enzymatic activities and cell viabilities. While the ion intercalation of MoS 2 in enzymatic activities is enabled via an external applied voltage, the intercalation of ions in cell viability investigations occurs in the presence of the intrinsic cell membrane potential.
An improved method for electrochemical deposition (ED) of a novel precursor (peripheral carbazole... more An improved method for electrochemical deposition (ED) of a novel precursor (peripheral carbazole substituted 9,9 ′ -spirobifluorene (TCPC)) for fabricating highly efficient luminescent films and devices has been developed. Electrochemical deposition often leaves residual charged ion species within the film. These species can negatively impact the performance of these films in OLED applications. The amount of residual charged species in the films can be reduced by controlling the oxidation and reduction potentials, by using electrolytes with different counter anions, and by washing with solvents. An optimized ED process showed a significant decrease in the doping level; up to 0.07% in ED film. The films prepared under a scan potential range from 0.85 to −0.8 V, using TBAAsF 6 as the supporting electrolyte, and washed with solvent mixtures of acetonitrile and CH 2 Cl 2 (V/V = 2/3) demonstrated excellent device performance. Light-emitting devices fabricated by electrochemical deposition achieved deep blue emission (x, y) = (0.16, 0.06) in CIE coordinates. High luminance efficiencies of 2.3 cd A −1 were achieved for single-layer device; luminescence efficiencies of 4.4 cd A −1 were achieved for a double-layer device. Finally, the problem that ED films usually exhibit low electroluminescent efficiency is solved.
ABSTRACT An oligomer of polyfluorene, ter(9,9, 9″,9″-bihexyl-9′,9′-diphenyl)fluorenes (THPF), is ... more ABSTRACT An oligomer of polyfluorene, ter(9,9, 9″,9″-bihexyl-9′,9′-diphenyl)fluorenes (THPF), is used as a blue-emitting material to achieve efficient pure blue electroluminescence. Based on a 4,4′,4″-tri(N-carbazolyl)-triphenylamine hole-transporting layer, a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline hole-blocking layer, an (8-hydroxyquinoline) aluminum electron-transporting layer, and a LiF/Al cathode, the device has two emission peaks at 404 and 424 nm, chromaticity coordinates at (0.18, 0.09), and a maximum efficiency of 1.27 cd/A. By using a submonolayer of 5,6,11,12-tetraphenylnaphthacene as a carrier detector, we demonstrate that THPF functions well as an electron-transporting layer, similar to Alq.
On page 144, Kourosh Kalantar-zadeh, Arnan Mitchell, and co-workers introduce liquid metal marble... more On page 144, Kourosh Kalantar-zadeh, Arnan Mitchell, and co-workers introduce liquid metal marbles by encapsulating droplets of liquid metal in micro/nanoparticles that are insulating or semiconducting. The physical properties of the liquid metal marbles are investigated. The ability to form active electronic junctions using liquid metal marbles and its use as a highly sensitive, electrochemical-based, heavy metal ion sensor is demonstrated.
Abstract Liquid metal marbles that are droplets of liquid metal encapsulated by micro-or nanopart... more Abstract Liquid metal marbles that are droplets of liquid metal encapsulated by micro-or nanoparticles are introduced. Droplets of galinstan liquid metal are coated with insulators (including Teflon and silica) and semiconductors (including WO 3, TiO 2, MoO 3, In 2 O 3 and carbon nanotubes) by rolling over a powder bed and also by submerging in colloidal suspensions. It is shown that these marbles can be split and merged, can be suspended on water, and are even stable when moving under the force of gravity and impacting a flat ...
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