Near-Infrared Light-Driven Controllable Motions of Gold-Hollow

Subscriber access provided by UNIV OF LOUISIANA

Functional Nanostructured Materials (including low-D carbon)

Near-Infrared Light-Driven Controllable Motions of Gold-Hollow-Microcone Array Hongxu Chen, Qilong Zhao, Yunlong Wang, Shilin Mu, Huanqing Cui, Juan Wang, Tengfei Kong, and Xuemin Du ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 11 Apr 2019 Downloaded from http://pubs.acs.org on April 11, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Near-Infrared Light-Driven Controllable Motions of Gold-Hollow-Microcone Array Hongxu Chen,1 Qilong Zhao,1 Yunlong Wang,1 Shilin Mu,2 Huanqing Cui,1 Juan Wang,1 Tengfei Kong,1 Xuemin Du*,1 1Institute

of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology

(SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China. 2State

Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin

University, Changchun, China. KEYWORDS: gold hollow microcone, plasmonic heating, light-driven, controllable motions, motor

ABSTRACT: Micro/nanomotors can effectively convert other forms of energy into mechanical energy, which have been widely used in microscopic fields. However, it is still challenging to integrate the micro/nanomotors to perform complex tasks for broad applications. Herein, a new mode for driving the collective motion behaviors of integrated micro/nanomotors in a liquid by plasmonic heating is reported. The integrated micro/nanomotors, constituted by gold hollow microcone array (AuHMA), are fabricated via colloidal lithography. Owing to the excellent plasmonic-heating property of AuHMA, the integrated micro/nanomotors can generate vapor bubbles in the liquid as exposure to near-infrared (NIR) irradiation, therefore inducing versatile motions via on/off NIR irradiation. The floating-diving motions are reversible for at least 60

ACS Paragon Plus Environment

1

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 28

cycles without fatigue. In addition, precise manipulation of the coordinated motion behaviors, including bending, convex, and jellyfish-like floating motions, can be realized by adjusting the irradiated positions of incident NIR light together with the sizes and shapes of AuHMA films. Moreover, the AuHMA film can act as a robust motor to drive a foam craft over 57 folds of its own weight as exposure to NIR irradiation. Our investigation into the NIR-driven AuHMA film provides a facile approach for obtaining integrated micro/nanomotors with controllable collective motions, which holds promise in remotely controlled smart devices and soft robotics in liquids.

INTRODUCTION Self-propelling micro/nanomotors can convert other forms of energy (light, magnetic, ultrasonic, electric or chemical energy) into mechanical properties, resulting in high-efficient propulsion and locomotion behaviors.1-6 The micro/nanomotors with different morphologies and various driven modes show excellent performances.7-14 In particular, some of them with asymmetrical structures/geometries (e.g., nanowires, Janus spheres, micro/nanorockets, etc.) can move to a predetermined destination through a predefined route, which have been applied in biomedical fields and environmental remediation, etc.15-19 Among them, the rocket-like micromotor with gold hollow microcone structure displays near-infrared (NIR) light-induced superfast propulsion capability, enabling NIR-triggered “on/off” motion in a remotely controllable manner. The asymmetrical morphology enables the rocket-like micromotor to efficiently move in cell culture media.20-21 Given the unique advantages of micro/nanomotors, particularly the NIR light controllable propulsion and motion manipulation of the rocket-like micromotors, it is therefore of great interest and promises to develop advanced remotely controllable locomotion systems for accomplishing complicated tasks in macroscopic field through the integration of these self-


2

Page 3 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


propelling units. The integrated micro/nanomotors are expected to possess controllable motion behaviors towards the target sites and programmable reconfiguration by site-specific stimuli of micro/nanomotor units, which can perform multiple tasks those are difficult or even impossible for conventional actuating systems. Recently, some efforts have been made for the assembly and collective motion manipulation of individual micro/nanomotor.22-26 Nevertheless, the integration of micro/nanomotors into one monolithic device remains challenging since the batch manufacturing and assembly of micro/nanomotors with complex asymmetrical geometries are difficult, which limits their application scopes in macroscopic fields. Our previous studies have demonstrated the facile assembly of micro/nanopillars into macroscopic well-arranged array by colloidal lithography.27-28 Herein, we extend this simple yet effective method for the assembly of rocket-like gold hollow microcones into one integrated film, which aims to achieve programmable actuation and motion of the film in macroscopic field manipulated by NIR light. In the current investigation, the film with well-arranged gold hollow microcone array (AuHMA) have been fabricated based on colloidal lithography. The gold hollow microcones as the propelling units enable effective photo-thermal energy conversion upon NIR irradiation, leading to plasmonic heating, which makes the temperature of the liquid inside the hollow microcones increasement, and subsequently the generation of bubbles and heat transfer to drive the floating-diving motions of the AuHMA film in the liquid. The AuHMA film shows high structural integrity and excellent recycle motion property with reversibly floating-diving vertical cycles for at least 60 times. In addition, a variety of collective motion behaviors, including bending, convex and jellyfish-like floating motions in the liquid, are realized by adjusting the incident NIR light positions with respect to the AuHMA film with different sizes and shapes (e.g., rectangular and cross shaped). Moreover, the AuHMA film can act as a robust motor to


3


Page 4 of 28

drive a foam craft over 57 folds of its own weight as exposure to NIR irradiation. Our study provides a new strategy for the direct integration of micro/nanomotors into one monolithic device, of which multiple motion behaviors in the liquid can be manipulated in a remote manner by combining with smart materials.29-34 These novel integrated micro/nanomotors will create new opportunities for photothermal motors, paving the way for developing the next generation of fuel-free smart devices and soft robotics for biomedical and environmental applications.35-38 EXPERIMENTAL SECTION Materials. Monodispersed polystyrene microspheres (5 μm) were obtained from Janus New Materials Co., Ltd. PCL. Silicon (100) wafers were cleaned by immersion into a solution of concentrated 98% H2SO4: 30% H2O2 (v/v: 7/3) at 80 °C for 4 h, then rinsed repeatedly with Milli-Q water (18.2 MΩ cm) and ethanol, and finally dried by N2 stream. Sodium dodecylsulfate (SDS), sulfuric acid, hydrogen peroxide, dichloromethane, acetone, chloroform and ethanol were purchased from Beijing Chemical Works. Fabrication of AuHMA Films. A layer of photoresist (AZ4620) was spincoated onto the silicon substrate and heated at 100 °C for 2 min to form flat film. Then the surface of film was treated into hydrophilic by oxygen plasma. Next, a monolayer of PS microspheres (5 μm) was deposited on the as-prepared substrate by the established interface method.39 Oxygen reactive ion etching, performed on an ICP-RIE DSE200S system, was applied for 420 s, eliminating the PS microspheres and generating the microcone array of the photoresist with an average height of ~ 4.88 μm. The etching procedure was performed at a pressure of 20 mTorr, a flow rate of 100 sccm, Src RF power of 300 W, and Bis RF Power of 100 W. Afterwards, the samples were


4

Page 5 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


vertically deposited 300 nm by a layer of Au (99.99%). The AZ4620 was washed away by ethanol, finally resulting in the AuHMA film. Fabrication of AuHMA Films with Different Shapes. For fabricating AuHMA films with square or rectangular shapes, the initial silicon substrate was pre-cut into certain shapes, followed by fabrication process described above. The AuHMA films with the identical shapes to those of the substrate were therefore prepared. In addition, the AuHMA film with cross shape was fabricated by sticking two rectangular shapes together. Finite-Difference Time-Domain Simulations. A commercial software package (FDTD Solutions v8.6.3, Lumerical Solutions Inc.) was used to perform the simulations of electromagnetic fields with the same structural parameters as obtained from the experimental samples. The structure was excited by a normally incident, unit magnitude plane wave propagating in the z direction with an electric field polarization along the x-axis. The optical parameters of Au were obtained from Johnson and Christy’s handbook. Characterizations. The morphology and structure of as-prepared films were characterized using a field-emission scanning electron microscope (Sigma, Carl Zeiss, Germany). All samples for SEM characterization were coated with thin layers of gold. The photographs and motion videos of AuHMA films were recorded using a digital camera (Canon, EOS Kiss X4). The reflection spectra of the AuHMA film was recorded using an optical microscope (Nikon Ni−U, Japan) and a fiber optic spectrometer (HR 2000+, Ocean Optics, United States). The infrared thermal images were recorded using an infrared thermometer (NEC R300SR). The AuHMA films were illuminated under an 808 nm NIR laser (5 W, Nanjing Laichuang Laser Technology Co., Ltd.).


5


Page 6 of 28

NIR-Controlled Motion Behaviors. The AuHMA film with a certain geometry was placed on the bottom of the cuvette filling with a liquid (typically ethanol), which was kept flat and straight. A laser beam is vertically irradiated onto the sample. For the square and rectangular AuHMA films, the distance between the NIR laser and the film to be irradiated was set as 1.0 cm. As for the cross-shaped the AuHMA film, the distance between the NIR laser and the film to be irradiated was set as 0.8 cm. RESULTS AND DISCUSSION Fabrication of AuHMA Film. The AuHMA film enabling NIR-triggered programmable motion was fabricated based on a colloidal lithography (Figure 1).40-41 In brief, hexagonal-close-packed polystyrene (PS) microspheres with a diameter of 5 μm were transferred onto the surface of a silicon substrate with a layer of photoresist via an interfacial method (Figure 2A), which were employed as the mask for etching the photoresist film. A reactive ion etching (RIE) treatment was then performed. With an increasing etching time, the diameters of PS microspheres gradually decreased (Figure S1, Supporting Information). After the PS mask was completely removed, the synchronic etching process on the photoresist resulted in periodically arranged microcone structures with an average height of approximately 4.88 μm and an average base diameter of approximately 2.85 μm (Figure 2B). Rather than smooth surface, but shallow grooves were exhibited in these microcones. A layer of gold film with a thickness of 300 nm was then vertically deposited onto the substrate by sputtering to completely cover the microcones of photoresist, resulting in intact and well-preserved gold microcone structures (Figure 2C). Subsequently, the resulting samples were immersed into ethanol to remove the photoresist film between the Au film and the silicon substrate, where the Au film was released. The resulting Au film presents well-arranged microcone array morphology (Figure 2D), of which structure is


6

Page 7 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


flexible and uniform over a large area (Figure 2E). In particular, the rocket-like hollow structures of the Au microcones could be clearly observed in the scanning electron microscopy (SEM) image at a high magnification (Figure 2F), demonstrating the successful formation of the AuHMA film with integrating and monolithic structure. Optical Properties of AuHMA Film. To demonstrate the plasmonic heating of the resulting AuHMA film, its surface plasmon resonance (SPR) property was firstly studied. As shown in Figure 3A, the reflection spectrum of the AuHMA film possesses two distinct featured troughs. The trough at 524 nm is attributed to Au nanoparticles, which were formed during the Au deposition. The characteristic trough at 790 nm is attributed to the hollow microcone structure.21, 42 To

better understand the optical properties of AuHMA film in the NIR region, finite-difference

time-domain (FDTD) simulations for the distribution of electric field have been performed. The results show that the electric fields are dominated in the tip region of the Au hollow microcone (Figure 3B, C), which further verified that the featured trough at 790 nm of the AuHMA film is generated by the gold hollow microcone structure. The field distribution diagram of a Au hollow microcone correlates to the temperature distribution, indicating that the temperature increases as close to the tip of the microcone.21 To verify the plasmonic heating of the AuHMA film upon NIR irradiation, infrared images were captured using an infrared thermal imaging spectrometer, and the detailed temperature changes of the AuHMA film immersed in the liquid upon exposure to a NIR laser beam were mapped (Figure 3D). The temperature of the illumination position increases with an increase of the irradiation time, which reaches 80 °C within 8 s and drops to 30 °C after removing the NIR light. In contrast, the temperature change of a flat gold film under the same condition was negligible since the temperature of the film reaches only 35 °C within 8 s NIR irradiation (Figure S2), further confirming the dominating role of the AuHMA on the


7


Page 8 of 28

plasmonic heating. The excellent photothermal property of the AuHMA makes the AuHMA film promising to realize controllable motions triggered by NIR light. Floating-Diving Vertical Motions. Owing to the unique structural and photothermal properties of AuHMA, the AuHMA film was found to obtain interesting NIR light-triggered motion capabilities in the liquid. First, the floating-diving vertical motions of a AuHMA film with a square shape (0.75 cm × 0.75 cm, Figure S4A) in ethanol have been achieved by on/off switchable NIR light (Figure 4B). The typical whole process of the floating-diving vertical motions of the AuHMA film was recorded (Movie S1, Supporting Information), of which stepwise images illustrate the conditions of the film at its original, NIR-on situations, respectively. To be specific, the AuHMA film initially sunk at the bottom of a cuvette. Upon NIR illumination, the film rapidly floated to the surface of liquid, travelling a distance of 0.8 cm in 2 s, while many bubbles could be observed during the floating process (indicated by red arrow in Figure 4B). After removing the NIR laser, the bubbles disappeared and the AuHMA film dived back to the bottom of the container in 6 s. The floating-diving motions of the film are supposed to be determined by the buoyancy force from the bubbles generated by the plasmonic heating of the AuHMA and the heat transfer between the cold and hot solvent molecules.21 Upon NIR irradiation, the AuHMA was able to convert the absorbed light energy into heat owing to its plasma resonance absorption in the NIR region. The induced plasmonic heating rapidly raised the temperature inside the hollow microcones, which resulted in vast amounts of vapor bubbles. Additionally, the hot microcones acted as heating sources which generate local temperature gradients both outside and inside of the microcones as further exposure to NIR irradiation. Thus, the temperature gradients cause convection between cold and hot solvent molecules. The generated bubbles together with convection effect enhanced the buoyancy of the microcone


8

Page 9 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


array, which leading to the floating motion of the AuHMA film when the buoyancy beyond the gravity of the film.21 Once the NIR light was turned off, the buoyancy force decreased accordingly. Thus, the gravity pulled the AuHMA film back to the bottom (Figure 4A). In contrast, the flat gold film with similar thickness to the AuHMA film yet without microcone array structures did not show NIR-driven floating-diving motion properties due to its isotropic homogeneity and limited photothermal effects. In addition, the floating-diving vertical motions of the AuHMA film in the ethanol could be repeated for at least 60 cycles without any fatigue controlled by the on/off switchable NIR light (Figure 4C), suggesting excellent durability of the film, as well as good structural integrity and flexibility of such film consisting of integrating gold hollow microcones. The floating speed of the AuHMA film with respect to the light intensity was then studied. The light intensity was tuned by changing the distance between the NIR light source and the film at an range from 34 W/cm2 to 7.9 W/cm2. The decreasing NIR light intensity causes an according decrease in the floating speed of the AuHMA film from 6 mm/s to 1 mm/s (Figure 4D). It is reasonable that the floating speed is varied by different energy inputs. Importantly, the AuHMA film possess the ability to deliver macroscopic object in a directional manner at a high NIR irradiation intensity (Figure 4E and Movie S2, Supporting Information). Specifically, a blue film with 4.5 times of the AuHMA film’s weight was loaded on the AuHMA film, which could be delivered in ethanol from the bottom to the upper surface under the 16 s illumination of NIR light. Decreasing the weight of the cargo increases the floating velocity (Figure S3). Moreover, the NIR light-triggered floating-diving vertical motion behaviors of the AuHMA film in various liquids with different boiling points, such as dichloromethane, acetone and chloroform were investigated. Noting that the floating speed decreases with an increase in the boiling point of the


9


Page 10 of 28

liquids (Figure 4F), resulting from the faster generation of vapor bubbles in lower boiling point liquid as exposure to NIR irradiation, and thus ensuring the faster floating speed, which further verifies the bubble-driving mechanism of the motion of the film and may also provide a potential approach for distinguishing different solvents using the NIR-driven floating speeds of the AuHMA film as an indicator.

NIR-Triggered Local Actuations. In addition to the above-mentioned floating-diving vertical motions, multiple programmable motion behaviors can be facilely realized by the site-specific NIR stimuli on the AuHMA films with various sizes and shapes. For instance, once NIR irradiating at different positions of a rectangular AuHMA film (0.75 cm × 2 cm, Figure S4B), the corresponding positions bend upward within several seconds (Figure S5 and Movie S3, Supporting Information). To be specific, only the left side of rectangular AuHMA film bends upward as the NIR laser spot irradiates the left position of the film, while only the right side of the film bends upward upon NIR irradiation in the right side. After removing the NIR source, the bended part recovers to the initial state. Such AuHMA film exhibits reversible bending/flatting actuation behaviors upon on-off NIR irradiation. Due to the intriguing actuation properties, the large-area rectangular AuHMA film can float in ethanol via continuous NIR irradiation at different sites (Figure 5A and Movie S4 in the Supporting Information). As the middle position exposure to NIR irradiation, the rectangular AuHMA film floats upward to form an arch in 22 s. Subsequently, the left side of the rectangular AuHMA film floats in 2 s upon NIR irradiation. Shortly after, the laser spot is moved to the right side of the film, leading to the floating of the rectangular AuHMA film to the surface of ethanol in 3 s. The floating middle position resulted from the enhancement of buoyancy of the AuHMA film, which is beneficial to the floating motions of the left and right positions as exposure to NIR irradiation. After removing NIR


10

Page 11 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


irradiation, the floating film gradually sinks to the bottom of the cuvette in 7 s. In order to better demonstrate the floating process, the moving heights of different positions of the rectangular AuHMA film at different times under NIR irradiation, captured from Movie S4 (Supporting Information), are shown in Figure 5B, which are well consistent with the results shown in Figure 5A. Moreover, the actuating speed of different locations irradiated by NIR light is further investigated, as shown in Figure 5C. Compared the actuating speed of the film with NIR irradiation at left or right side, the speed of irradiation at the middle position is the slowest. The speed decreases as decreasing the distance between the irradiated position and the middle position because of the higher driving force to against gravity and the resistance of the whole film during the floating process (Figure 5C, Figure S5, Supporting Information).

The precise manipulation of AuHMA film with a complex shape could be also realized by adjusting the incident NIR light positions with respect to the film. As shown in Figure 6 and Movie S5 (Supporting Information), when NIR laser irradiated at the center (position 1) of the AuHMA film, the central hollow microcones absorb NIR light to drive the center of the film upward floats. Similarly, once the NIR laser sequentially irradiating other four sides of the AuHMA film, the corresponding positions of the film float upwards in the same sequence. Finally, the AuHMA film completely floats from the bottom of cuvette to the liquid surface (Figure 6B). These intriguing results reveal the promising prospect of the NIR-triggered local actuations for the construction of advanced biomimetic devices in diverse practical application fields.

Versatile Motions. The superior NIR light-triggered actuating and site-specific responsive properties of the AuHMA film with well-defined geometries bring the possibility to realize the


11


Page 12 of 28

remotely controlled motion of artificial materials resembling the freestanding swimming of biological systems such as jellyfish. In our investigation, a cross shaped AuHMA film was constructed to imitate the jellyfish, consisting of a body part and four tentacles-like structures (Figure S4C). NIR irradiation was applied onto the body part of the jellyfish-like film. The film initially could not float at a low NIR light intensity (the distance between the laser and the film was 1.2 cm) since the driving force was insufficient (Movie S6, Supporting Information). After the distance between the laser and the film was shortened from 1.2 cm to 0.8 cm, vast amount of bubbles was generated at the irradiating site (i.e., the body site) of the jellyfish-like film, resulting in higher buoyancy to drive this part of the film float (Figure 7A and Movie S7, Supporting Information). Under continuous illumination, the partial floating of the jellyfish-like film would make the body part of the film float higher with prolonged irradiation time, which would drive the four “tentacles” gradually move closer to the centered body part and subsequently the floating of the entire film (Figure 7B). The stepwise states of the jellyfish-like film during floating from its initially relax state to the following contractile state mimic the floating motion of a living jellyfish. Moreover, the motion was not limited in organic solvents but was also demonstrated on the water surface. As shown in Figure 7C, a 0.4 cm × 0.4 cm AuHMA film (0.3 mg) was adhered onto the back surface of a foam craft (17.1 mg). Notably, it acted as a robust motor to drive over 57 folds of its own weight towards a specific direction at an average speed of 3.2 mm/s as exposure to NIR irradiation. The on/off motion of the foam craft can be controlled by the on/off states of the NIR light source (Movie S8). These novel integrated micro/nanomotors will create new opportunities for photothermal motors via a combination of 3D printing, paving the way for developing the next generation of fuel-free smart devices and soft robotics for biomedical and environmental applications.43


12

Page 13 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CONCLUSIONS In summary, we demonstrated a novel colloidal lithography-based method for integrating rocketlike gold hollow microcones into one flexible monolithic film that enables NIR-triggered programmable motion in macroscopic field. Upon the site-specific stimuli of the gold hollow microcones on the film via NIR irradiation, bubbles and convection heat transfer are generated by plasmonic heating at the irradiating regions of the film, which drive the film programmable motion in various patterns. Not only floating-diving vertical motions, but also site-specific bending, convex and jellyfish-like floating motions are realized using the AuHMA film with different geometries by adjusting the irradiating position of the NIR laser. Furthermore, the AuHMA film can act as a robust motor to drive over 57 folds of its own weight towards a specific direction as exposure to NIR irradiation. The on/off motion of the foam craft can be controlled by the on/off states of the NIR light source. The film enabling multiple controllable motions via a remote route has great potential to act as advanced actuating devices for various practical applications. And the film with the special NIR- responsive AuHMA structure can be further coupled with other smart materials, which will be promising to obtain multifunctional actuating systems with superior controllability and multi-modal responsiveness. These novel integrated motors will pave the way for developing the next generation of fuel-free smart devices and soft robotics for biomedical and environmental applications.

Supporting Information


13


Page 14 of 28

SEM images of PS microsphere array with an increase of etching time (Figure S1), infrared thermal images of the flat gold film without hollow microcone structure under NIR illumination (Figure S2), the speed of the AuHMA film loaded by cargos with different weights (Figure S3), optical photographs of the top view of the AuHMA films (Figure S4), optical photographs of the shape deformation of the rectangular AuHMA film upon the NIR irradiation at different positions (Figure S5), and the movies of NIR light-driven motions of a AuHMA film in ethanol (Movie S1-S7) and on the water surface (Movie S8).

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. (X. D.) ORCID Hongxu Chen: 0000-0003-2377-5733 Qilong Zhao: 0000-0001-5346-3656 Yunlong Wang: 0000-0001-7455-8064 Shilin Mu: 0000-0003-0066-8038 Huanqing Cui: 0000-0002-0804-5890 Juan Wang: 0000-0001-5254-5772 Tengfei Kong: 0000-0002-0981-7346


14

Page 15 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Xuemin Du: 0000-0002-0200-5759 Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by National Key R&D Program of China (2017YFA0701303), the Youth Innovation Promotion Association of CAS, CAS Key Laboratory of Health Informatics, Shenzhen Institutes of Advanced Technology, the Special Support Project for Outstanding Young Scholars of Guangdong Province (2015TQ01R292), Guangdong-Hong Kong Technology Cooperation Funding (2017A050506040), Shenzhen Science and Technology Innovation Committee (JCYJ20170413152640731), and Shenzhen Peacock Plan. REFERENCES (1) Paxton, W. F.; Kistler, K. C.; Olmeda, C. C.; Sen, A.; Angelo, S. K.; Cao, Y.; Mallouk, T. E.; Lammert, P. E.; Cresp, V. H. Catalytic Nanomotors: Autonomous Movement of Striped Nanorods. J. Am. Chem. Soc. 2004, 126, 13424-13431. (2) Medina-Sánchez, M.; Magdanz, V.; Guix, M.; Fomin, V. M.; Schmidt, O. G. Swimming Microrobots: Soft, Reconfigurable, and Smart. Adv. Funct. Mater. 2018, 28, 1707228. (3) Sanchez, S.; Soler, L.; Katuri, J. Chemically Powered Micro- and Nanomotors. Angew. Chem., Int. Ed. 2015, 54, 1414-1444. (4) Xu, L.; Mou, F.; Gong, H.; Luo, M.; Guan, J. Light-Driven Micro/Nanomotors: From Fundamentals to Applications. Chem. Soc. Rev. 2017, 46, 6905-6926. (5) Xu, T.; Gao, W.; Xu, L.; Zhang, X.; Wang, S. Fuel-Free Synthetic Micro-/Nanomachines. Adv. Mater. 2017, 29, 1603250.


15


Page 16 of 28

(6) Chen, H.; Zhao, Q.; Du, X. Light-Powered Micro/Nanomotors. Micromachines 2018, 9, 41. (7) Zhang, L.; Petit, T.; Lu, Y.; Kratochvil, B. E.; Peyer, K. E.; Pei, R.; Lou, J.; Nelson, B. J. Controlled Propulsion and Cargo Transport of Rotating Nickel Nanowires Near a Patterned Solid Surface. ACS Nano 2010, 4, 6228-6234. (8) Xuan, M.; Wu, Z.; Shao, J.; Dai, L.; Si, T.; He, Q. Near Infrared Light-Powered Janus Mesoporous Silica Nanoparticle Motors. J. Am. Chem. Soc. 2016, 138, 6492-6497. (9) Li, T.; Li, J.; Morozov, K. I.; Wu, Z.; Xu, T.; Rozen, I.; Leshansky, A. M.; Li, L.; Wang, J. Highly Efficient Freestyle Magnetic Nanoswimmer. Nano Lett. 2017, 17, 5092-5098. (10) Lee, T.-C.; Alarcón-Correa, M.; Miksch, C.; Hahn, K.; Gibbs, J. G.; Fischer, P. SelfPropelling Nanomotors in the Presence of Strong Brownian Forces. Nano Lett. 2014, 14, 24072412. (11) Li, T.; Zhang, A.; Shao, G.; Wei, M.; Guo, B.; Zhang, G.; Li, L.; Wang, W. Janus Microdimer Surface Walkers Propelled by Oscillating Magnetic Fields. Adv. Funct. Mater. 2018, 28, 1706066. (12) Xu, T.; Soto, F.; Gao, W.; Dong, R.; Garcia-Gradilla, V.; Magana, E.; Zhang, X.; Wang, J. Reversible Swarming and Separation of Self-Propelled Chemically Powered Nanomotors under Acoustic Fields. J. Am. Chem. Soc. 2015, 137, 2163-2166. (13) You, M.; Chen, C.; Xu, L.; Mou, F.; Guan, J. Intelligent Micro/nanomotors with Taxis. Acc. Chem. Res. 2018, 51, 3006-3014. (14) Chen, C.; Mou, F.; Xu, L.; Wang, S.; Guan, J.; Feng, Z.; Wang, Q.; Kong, L.; Li, W.; Wang, J.; Zhang, Q. Light-Steered Isotropic Semiconductor Micromotors. Adv. Mater. 2017, 29, 1603374.


16

Page 17 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(15) Li, J.; de Ávila, B. E.-F.; Gao, W.; Zhang, L.; Wang, J. Micro/Nanorobots for Biomedicine: Delivery, Surgery, Sensing, and Detoxification. Sci. Robot. 2017, 2, eaam6431. (16) Soler, L.; Magdanz, V.; Fomin, V. M.; Sánchez, S.; Schmidt, O. G. Self-Propelled Micromotors for Cleaning Polluted Water. ACS Nano 2013, 7, 9611-9620. (17) Uygun, M.; Singh, V. V.; Kaufmann, K.; Uygun, D. A.; de Oliveira, S. D.; Wang, J. Micromotor-Based Biomimetic Carbon Dioxide Sequestration: Towards Mobile Microscrubbers. Angew. Chem., Int. Ed. 2015, 54, 12900-12904. (18) Guix, M.; Mayorga-Martinez, C. C.; Merkoci, A. Nano/Micromotors in (Bio)Chemical Science Applications. Chem. Rev. 2014, 114, 6285-6322. (19) Ma, X.; Jang, S.; Popescu, M. N.; Uspal, W. E.; Miguel-López, A.; Hahn, K.; Kim, D.-P.; Sánchez, S. Reversed Janus Micro/Nanomotors with Internal Chemical Engine. ACS Nano 2016, 10, 8751-8759. (20) Wu, Z.; Lin, X.; Wu, Y.; Si, T.; Sun, J.; He, Q. Near-Infrared Light-Triggered “On/Off” Motion of Polymer Multilayer Rockets. ACS Nano 2014, 8, 6097-6105. (21) Wu, Z.; Si, T.; Gao, W.; Lin, X.; Wang, J.; He, Q. Superfast Near-Infrared Light-Driven Polymer Multilayer Rockets. Small 2016, 12, 577-582. (22) Ismagilov, R. F.; Schwartz, A.; Bowden, N.; Whitesides, G. M. Autonomous Movement and Self-Assembly. Angew. Chem., Int. Ed. 2002, 41, 652-654. (23) Dai, B.; Wang, J.; Xiong, Z.; Zhan, X.; Dai, W.; Li, C.-C.; Feng, S.-P.; Tang, J. Programmable Artificial Phototactic Microswimmer. Nat. Nanotechnol. 2016, 11, 1087-1092. (24) Lin, Z.; Si, T.; Wu, Z.; Gao, C.; Lin, X.; He, Q. Light-Activated Active Colloid Ribbons. Angew. Chem., Int. Ed. 2017, 56, 13517-13520.


17


Page 18 of 28

(25) Chen, J.-X.; Chen, Y.-G.; Kapral, R. Chemically Propelled Motors Navigate Chemical Patterns. Adv. Sci. 2018, 5, 1800028. (26) Singh, D. P.; Choudhury, U.; Fischer, P.; Mark, A. G. Non-Equilibrium Assembly of LightActivated Colloidal Mixtures. Adv. Mater. 2017, 29, 1701328. (27) Chen, H.; Wang, T.; Shen, H.; Liu, W.; Wang, S.; Liu, K.; Zhang, J.; Yang, B. Ag Nanoparticle/Polymer Composite Barcode Nanorods. Nano Res. 2015, 8, 2871-2880. (28) Chen, H.; Mu, S.; Fang, L.; Shen, H.; Zhang, J.; Yang, B. Polymer-Assisted Fabrication of Gold Nanoring Arrays. Nano Res. 2017, 10, 3346-3357. (29) Zhao, Q.; Wang, J.; Cui, H.; Chen, H.; Wang, Y.; Du, X. Programmed Shape-Morphing Scaffolds Enabling Facile 3D Endothelialization. Adv. Funct. Mater. 2018, 28, 1801027. (30) Lv, J.; Liu, Y.; Wei, J.; Chen, E.; Qin, L.; Yu, Y. Photocontrol of Fluid Slugs in Liquid Crystal Polymer Microactuators. Nature 2016, 537, 179-184. (31) Zhang, L.; Naumov, P.; Du, X.; Hu, Z.; Wang, J. Vapomechanically Responsive Motion of Microchannel Programmed Actuators. Adv. Mater. 2017, 29, 1702231. (32) Du, X.; Cui, H.; Sun, B.; Wang, J.; Zhao, Q.; Xia, K.; Wu, T.; Humayun, M. S. Photothermally Triggered Shape-Adaptable 3D Flexible Electronics. Adv. Mater. Technol. 2017, 2, 1700120. (33) Wang, J.; Zhao, Q.; Cui, H.; Wang, Y.; Chen, H.; Du, X. Tunable Shape Memory Polymer Mold for Multiple Microarray Replications. J. Mater. Chem. A 2018, 6, 24748-24755. (34) Du, X.; Cui, H.; Zhao, Q.; Wang, J.; Chen, H.; Wang, Y. Inside-Out 3D Reversible IonTriggered Shape-Morphing Hydrogels. Research 2019, DOI: 10.1155/2019/6398296. (35) Park, S.-J.; Gazzola, M.; Park, K. S.; Park, S.; Di Santo, V.; Blevins, E. L.; Lind, J. U.; Campbell, P. H.; Dauth, S.; Capulli, A. K.; Pasqualini, F. S.; Ahn, S.; Cho, A.; Yuan, H.; Maoz,


18

Page 19 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


B. M.; Vijaykumar, R.; Choi, J.-W.; Deisseroth, K.; Lauder, G. V.; Mahadevan, L.; Parker, K. K.; Phototactic Guidance of A Tissue-Engineered Soft-Robotic Ray. Science 2016, 353, 158-162. (36) Li, T.; Li, G.; Liang, Y.; Cheng, T.; Dai, J.; Yang, X.; Liu, B.; Zeng, Z.; Huang, Z.; Luo, Y.; Xie, T.; Yang, W. Fast-Moving Soft Electronic Fish. Sci. Adv. 2017, 3, e1602045. (37) Nawroth, J. C.; Lee, H.; Feinberg, A. W.; Ripplinger, C. M.; McCain, M. L.; Grosberg, A.; Dabiri, J. O.; Parker, K. K. A Tissue-Engineered Jellyfish with Biomimetic Propulsion. Nat. Biotechnol. 2012, 30, 792-797. (38) Qiu, T.; Lee, T.-C.; Mark, A. G.; Morozov, K. I.; Münster, R.; Mierka, O.; Turek, S.; Leshansky, A. M.; Fischer, P. Swimming by Reciprocal Motion at Low Reynolds Number. Nat. Comm. 2014, 5, 5119. (39) Rybczynski, J.; Ebels, U.; Giersig, M. Large-Scale, 2D Arrays of Magnetic Nanoparticles. Colloids Surf. A 2003, 219, 1-6. (40) Zhang, J.; Li, Y.; Zhang, X.; Yang, B. Colloidal Self-Assembly Meets Nanofabrication: From Two-Dimensional Colloidal Crystals to Nanostructure Arrays. Adv. Mater. 2010, 22, 42494269. (41) Zhang, J.; Yang, B. Patterning Colloidal Crystals and Nanostructure Arrays by Soft Lithography. Adv. Funct. Mater. 2010, 20, 3411-3424. (42) Ai, B.; Yu, Y.; Möhwald, H.; Wang, L.; Zhang, G. Resonant Optical Transmission through Topologically Continuous Films. ACS Nano 2014, 8, 1566-1575. (43) Wu, L.; Dong, Z.; Du, H.; Li, C.; Fang, N. X.; Song, Y. Bioinspired Ultra-Low Adhesive Energy Interface for Continuous 3D Printing: Reducing Curing Induced Adhesion. Research 2018, 4795604.


19


Page 20 of 28

FIGURES

Figure 1. A schematic illustration of fabrication and floating-diving motions of AuHMA film. First, a photoresist film was spin-coated onto a silicon substrate, hexagonal-close-packed PS microspheres were then transferred to the surfaces of the photoresist via the interfacial method. Then reactive ion etching was conducted to completely etch the microspheres, resulting in photoresist film with a periodic microcone array. Subsequently, a gold film was vertically deposited onto the substrate. Later, the AuHMA film was obtained by immersing the sample into ethanol to remove the photoresist film between the Au film and the substrate. Finally, the AuHMA film is put into a cuvette containing ethanol, the film sinks to the bottom of the cuvette. Then the AuHMA film floated on the liquid surface under the NIR illumination.


20

Page 21 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. The morphologies of fabrication process of the AuHMA film are characterized by SEM. (A) The hexagonal-close-packed PS microspheres with a diameter of 5 μm. (B) The PS microspheres were used as a mask, reactive ion etching was used to completely etch away the microspheres and results in a periodic microcone array with a height of 4.88 μm and a base diameter of 2.85 μm. (C) A gold film with a thickness of 300 nm was vertically deposited onto the polymer microcone array. (D-F) The sample was immersed into ethanol to remove the photoresist film between Au film and the substrate, releasing the AuHMA film, which present well-defined uniformly hollow microcone structure over a large area.


21


Page 22 of 28

Figure 3. The optical properties of the AuHMA film. (A) Reflection spectrum of the Au hollow microcone array film. (B-C) The field distribution diagram of Au hollow microcone array using FDTD simulation. Normalized near-field electric field distribution simulated at the 790 nm wavelengths of hollow microcone array. The structure was excited by a normally incident, unit magnitude plane wave propagating in the z direction with an electric field polarization along the x-axis. (D) Infrared thermal images of the AuHMA film with NIR irradiation on and off. Temperature change of the AuHMA film upon exposure to a laser (808 nm, the distance between the NIR light source and the film is 1.0 cm), the temperatures reaches 80 °C in 8 s, and subsequently drops to 30 °C in 2 s upon turning off the NIR light (fast cooling).


22

Page 23 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. (A) Schematic illustration of motion mechanism of the AuHMA film in the liquid. Upon NIR irradiation, the induced plasmonic heating of gold hollow microcones results in the generation of vast amounts of vapor bubbles, which provide a propulsion for the motion of AuHMA film. (B) The characterization of the floating-diving process of AuHMA film in the ethanol. The AuHMA film sinks to the bottom of the cuvette without the NIR illumination, then gradually floats on the ethanol surface under the NIR illumination. Bubbles can be observed


23


Page 24 of 28

during the floating process (red arrow). (C) The floating-diving vertical motions for at least 60 cycles in the ethanol triggered by NIR. The inset pictures are the positions of AuHMA film in the liquid. (D) The floating speed of the AuHMA film under the NIR irradiation with different light intensity. The floating speed of the AuHMA film gradually increases with an increase of the NIR light intensity. The speed is 1 mm/s at 7.9 W/cm2 and increases to 6 mm/s at 34 W/cm2. The insets are the optical images of the corresponding NIR laser positions. (E) The floating-diving process of blue film-loaded AuHMA film by the NIR on/off in the liquid. This AuHMA film could drive an object (4.5 times of its weight) to float to ethanol surface after NIR irradiation for 16 s. (F) The responsive speed of AuHMA film in different solvents. Black line represents the speed, and the red line indicates the boiling point of the different solvents. The floating speed increases with the decrease in the boiling point of the liquids. The AuHMA film is 0.75 cm × 0.75 cm, the distance between the NIR light source and the film is 1.0 cm.


24

Page 25 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. (A) NIR light-driven floating-diving cycle motions of rectangular AuHMA film. When the middle position of rectangular AuHMA film is irradiated by NIR light, the rectangular AuHMA film floats upward to form an arch. Then the left of the rectangular AuHMA film subsequent floats upon NIR irradiation the left side. Shortly after, the laser is moved from left to right side, the rectangular AuHMA film completely floats on the surface of the ethanol. After removing NIR irradiation, the floating film gradually sinks to the bottom of the cuvette. (B) Moving height of rectangular AuHMA film on different positions under NIR irradiation, the floating heights are obtained from the Movie S4 (Supporting Information). The inset picture shows seven sites used to record the height variation in different NIR irradiating times. (C) The responsive speed of rectangular AuHMA film irradiated at different positions. The left is 5.3 mm away from the middle position and the right is 6.7 mm away from the middle position. The inset pictures are motion schematic illustration of AuHMA film irradiated at different position. The rectangular AuHMA film is 0.75 cm × 2 cm, the distance between the NIR light source and the film is 1.0 cm.


25


Page 26 of 28

Figure 6. (A) Schematic diagram of NIR light precisely controlled the motion of AuHMA film. (B) The floating motion of AuHMA film under the NIR irradiation. When NIR laser irradiated at the center (position 1) of the AuHMA film, the hollow microcones in center region absorb NIR light and upward floats. Similarly, the NIR laser sequential irradiated onto the four sides of AuHMA film, the corresponding positions float upwards in sequence. Finally, the whole AuHMA film achieves the completely floating from the bottom of cuvette to ethanol surface. The sample is prepared by adhering two pieces of rectangular AuHMA film together (1.6 cm × 0.6 cm), the distance between the NIR light source and the film is 0.8 cm.


26

Page 27 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. (A) Optical images of the jellyfish-like floating motion under the NIR irradiation. Without NIR irradiation, the film keeps stable. When exposed to the NIR irradiation, the body part (center) of the biomimetic jellyfish begins to absorb energy and generate bubbles, which lead to the body of biomimetic jellyfish upward float, thereby driving four tentacles gradually move closer to the center. Under continuous illumination, the body of the jellyfish upward floats higher, the four tentacles move closer, thus contributing to the completely float of the jellyfish, which mimicking the floating behavior of jellyfish. (B) The height changes of center position of jellyfish under NIR irradiation. The inset pictures show schematic illustration of the motion state of jellyfish at the corresponding height. (C) The AuHMA film (0.4 cm × 0.4 cm) can be used as a


27


Page 28 of 28

robust motor to drive a foam craft over 57 folds of its own weight towards a specific direction on the water surface as exposure to NIR irradiation.

Table of Contents Graphic


28

Near-Infrared Light-Driven Controllable Motions of Gold-Hollow

Recommend Documents