Microrobots have attracted considerable attention due to their extensive applications in microobject manipulation and targeted drug delivery. To realize more complex micro-/nanocargo manipulation ...(e.g., encapsulation and release) in biological applications, it is highly desirable to endow microrobots with a shape-morphing adaptation to dynamic environments. Here, environmentally adaptive shape-morphing microrobots (SMMRs) have been developed by programmatically encoding different expansion rates in a pH-responsive hydrogel. Due to a combination with magnetic propulsion, a shape-morphing microcrab (SMMC) is able to perform targeted microparticle delivery, including gripping, transporting, and releasing by “opening–closing” of a claw. As a proof-of-concept demonstration, a shape-morphing microfish (SMMF) is designed to encapsulate a drug (doxorubicin (DOX)) by closing its mouth in phosphate-buffered saline (PBS, pH ∼ 7.4) and release the drug by opening its mouth in a slightly acidic solution (pH < 7). Furthermore, localized HeLa cell treatment in an artificial vascular network is realized by “opening–closing” of the SMMF mouth. With the continuous optimization of size, motion control, and imaging technology, these magnetic SMMRs will provide ideal platforms for complex microcargo operations and on-demand drug release.
Rationally designed artificial chiral architectures have found broad applications in various fields. In article number 2002356, Yanlei Hu, Dong Wu, and co‐workers describe how highly ordered chiral ...microstructures can be spontaneously assembled by the meniscus‐directed capillary force arising in an evaporating liquid. The chirality is facilitated by rationally breaking the intrinsic symmetry through cooperative control of the geometry and spatial topology of the pillar unit cells.
For microscale 4D photoresponsive actuators, light is crucial in two ways. First, the underlying additive manufacturing techniques rely on photopolymerization processes triggered by the absorption of ...light. Second, the absorption of light serves as the actuation stimulus. The two absorptions can be conflicting. While the microstructure requires strong absorption at the actuation wavelength(s), this absorption should not interfere with that of the manufacturing process. Herein, a simple strategy is proposed to overcome these limitations and allow for the fabrication of multi‐photoresponsive 3D microstructures that can be actuated at different wavelengths of light. Two‐photon 3D laser printing is selected as the fabrication technique and liquid crystalline (LC) elastomers as the functional materials. In a first step, 3D microstructures are fabricated using an aligned LC ink formulation. Thereafter, up to five different dyes exhibiting absorptions that extend over the entire visible regime (400–700 nm) are successfully incorporated into the LC microstructures by an exchange process enabling a programmable actuation by irradiating with the suitable wavelength. Furthermore, by combining dyes exhibiting orthogonal absorptions, wavelength‐selective actuations are demonstrated.
A simple strategy allowing for the fabrication of multi‐phototoresponsive 4D microstructures using two‐photon laser writing that can be actuated at different wavelengths of light, is presented. In particular, three classes of dyes (azobenzenes, donor‐acceptor Stenhouse Adducts (DASAs), and anthraquinone) enabling actuation using blue, green or red light, respectively, are exploited.
The construction
of electrochemical energy-storage devices by scalable
thin-film microfabrication methods with high energy and power density
is urgently needed for many emerging applications. Herein, ...we demonstrate
an in-plane hybrid microsupercapacitor with a high areal energy density
by employing a battery-type CuFe-Prussian blue analogue (CuFe-PBA)
as the positive electrode and pseudocapacitive titanium carbide MXene
(Ti
3
C
2
T
x
) as the
negative electrode. A three-dimensional lignin-derived laser-induced
graphene electrode was prepared as the substrate by laser exposure
combined with an environmentally friendly water lift-off lithography.
The designed hybrid device achieved enhanced electrochemical performance
thanks to the ideal match of the two types of high-rate performance
materials in proton-based electrolytes and the numerous electrochemically
active sites. In particular, the device delivers a high areal capacitance
of 198 mF cm
–2
, a wide potential window (1.6 V),
an ultrahigh rate performance (75.8 mF cm
–2
retained
even at a practical/high current density of 100 mA cm
–2
), and a competitive energy density of 70.5 and 27.6 μWh cm
–2
at the power densities 0.74 and 52 mW cm
–2
, respectively. These results show that the Ti
3
C
2
T
x
/CuFe-PBA hybrid microsupercapacitors
are promising energy storage devices in miniaturized portable and
wireless applications.
The fluidity and high electrical conductivity of a liquid metal make it an excellent material for preparing flexible electronics. Here, we established a method utilizing a widespread laser-printing ...technique to manufacture 3D flexible electronics. Through digital constructing of liquid alloy-philic smooth toner on liquid alloy-phobic rough substrates, we have the liquid metal selectively adhered to the designed pattern. The liquid metal circuit can then be transferred to an uneven and deformable Ecoflex surface to form a 3D circuit. Computational fluid dynamics simulation was performed to interpret the printing mechanism of the liquid metal on a substrate with selected adhesion. Flexible electronics fabricated through this method reveal great performance and stability, opening up opportunities for office and home flexible electronics manufacture, especially for lighting, heating, and logistics. By making the full use of the laser printers, our method not only saves the cost and time in preparation but also identifies favorable prospects for the mature laser-printing industry to promote next-generation flexible electronics fabrication.
Compared to 3D laser nanoprinting of polymers, the mechanisms in laser nanoprinting of metals are rather poorly understood. For the example of platinum investigated here, the printing process starts ...with the formation of metal nanoparticles by photo‐reduction of metal salts in aqueous solution in a diffraction‐limited laser focus. To investigate the printing process in situ, a weak continuous‐wave probe laser is co‐focused in addition to the focused femtosecond printing laser. The light of the probe laser is backscattered off the emerging metal structures, and recorded with a temporal resolution of 1 µs. It is found that the formed metal nanoparticles are quickly ejected from the focus on a timescale of some 10 µs. Once a nanoparticle randomly adheres to the substrate surface, it serves as a seed from which structures can be built‐up. The following nanoparticles are sintered onto that seed to form a metallic voxel on a timescale of some 10 ms. By polarization‐dependent experiments and full‐wave optical simulations, it is shown that light‐induced forces onto the nanoparticles play a significant role. The improved understanding of the microscopic processes in metal nanoprinting is a prerequisite for further process optimizations and applications, for example in terms of printed optoelectronics.
By co‐focusing a weak continuous‐wave probe laser together with the intense femtosecond printing laser and time‐resolving the scattered light of the probe, the microscopic processes during sub‐micrometer laser printing of platinum are investigated in situ. Experiment and full‐wave simulations point to the importance of light‐induced forces onto the metal nanoparticles during the laser printing process.
We report an anomalous structural transformation of a Cu(I) cluster into two different types of copper‐silver (CuAg) alloy nanoclusters. Different from previous reports, we demonstrate that under ...specifically designed reaction conditions, the Ag‐doping could induce a substantial growth of the starting Cu15 and a Ag13Cu20 nanocluster was obtained via the unexpected insertion of an Ag13 kernel inside the Cu(I)‐S shell. Ag13Cu20 demonstrates high activity to initiate the photopolymerization of previously hard‐to‐print inorganic polymers in 3D laser microprinting. Interestingly, a slight modification of the reaction condition leads to the formation of another Ag18‐xCuxS (8≤x) nanocluster templated by a central S2− anion, which possesses a unique electronic structure compared to conventional template‐free CuAg nanoclusters. Overall, this work unveils the intriguing doping chemistry of Cu clusters, as well as their capability to create different types of alloy nanoclusters with previously unobtainable structures and multifunctionality.
We demonstrate a doping‐induced, anomalous structural transformation in Cu nanoclusters and uncovered its capability to create different types of alloy nanoclusters with previously unreported structures, properties and functionalities.
Porous SiC ceramics are preferable materials for industrial applications such as hot gas filtration and microfiltration, some areas of fine filtration exist where complex structures of ceramic ...components are required. In this study, a novel method was employed for preparing high‐flux ceramic membranes via selective laser printing. The powder used for laser printing is a laboratory‐prepared polysiloxane powder, which can be pyrolyzed under relatively lower temperatures to obtain SiOC ceramic membranes. From the results of characterization and testing, the obtained ceramic membranes exhibited inimitable pore microstructure, high porosity, and outstanding filtering performance. Laser printing demonstrated good potential to be a strong candidate for the next generation of ceramic membrane fabrication technology.
Nanogap plasmonic structures, which can strongly enhance electromagnetic fields, enable widespread applications in surface‐enhanced Raman spectroscopy (SERS) sensing. Although the directed ...self‐assembly strategy has been adopted for the fabrication of micro/nanostructures on open surfaces, fabrication of nanogap plasmonic structures on complex substrates or at designated locations still remains a grand challenge. Here, a switchable self‐assembly method is developed to manufacture 3D nanogap plasmonic structures by combining supercritical drying and capillary‐force driven self‐assembly (CFSA) of micropillars fabricated by laser printing. The polymer pillars can stay upright during solvent development via supercritical drying, and then can form the nanogap after metal coating and subsequent CFSA. Due to the excellent flexibility of this method, diverse patterned plasmonic nanogap structures can be fabricated on planar or nonplanar substrates for SERS. The measured SERS signals of different patterned nanogaps in fluidic environment show a maximum enhancement factor ≈8 × 107. Such nanostructures in microchannels also allow localized sensing for anticancer drugs (doxorubicin). Resulting from the marriage of top‐down and self‐assembly techniques, this method provides a facile, effective, and controllable approach for creating nanogap enabled SERS devices in fluidic channels, and hence can advance applications in precision medicine.
A method to fabricate a nanogap‐enabled microfluidic surface‐enhanced Raman spectroscopy (SERS) device is proposed by combining supercritical drying with capillary‐force driven self‐assembly (CFSA) of pillars prepared by laser printing. A model is built to analyze the CFSA of a Au‐polymer compound structure. The SERS sensing ability of different patterned nanogap structures in a microfluidic environment is demonstrated.
Direct laser scribing, an advanced printing technique, has been recently developed to enable the carbonization of carbonaceous precursors in a rapid, precise, and cost‐effective manner. Herein, it is ...reported that metal−organic frameworks (MOFs) can be converted into patterned derived carbon with desired structural features using a CO2 infrared laser system. Metal species in MOFs play a key role in the morphology, porous structure, and crystallinity of the resulting laser‐induced products by studying six representative MOFs. Diverse features such as ordered porous structure and continuous network microstructure can be obtained in the laser‐induced MOF‐derived carbon, which is influenced by the melting and boiling points of metals and their magnetic and catalytic behaviors. Furthermore, a core–shell structured composite (MOF‐199@ZIF‐67) has been designed and prepared for the fabrication of 12‐interdigital electrodes derived from the composite by laser‐assisted printing. The as‐obtained electrodes with highly porous and hierarchical structure show an enhanced specific capacitance for micro‐supercapacitors (MSCs). This work provides a complementary heat treatment method to produce MOF‐derived carbon nanomaterials with desired structural features and patterns for MSCs and micro‐device‐related applications.
Interdigital electrodes that exhibit ordered mesopores and hierarchical architecture are fabricated from metal–organic frameworks (MOFs) using a direct laser‐assisted printing technique. Based on metal species in MOFs, this technique can be used to prepare MOF‐derived carbon materials with diverse morphology and porous structure in a rapid, precise, and cost‐effective manner.
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