Here we show the use of a metal 3D printing system to fabricate bespoke electrochemical electrodes which can be used as platform for different electrochemical devices such as pseudocapacitor, catalytic setup for electrogeneration of oxygen, and pH sensor. We designed helicalshaped electrodes of different sizes to show the versatility of the technique able to accommodate complex shape designs. This represents a relatively simple geometry that can be easily printed, but at the same time reasonably complex that would require long process time to produce with standard methods (subtracting manufacturing) with large amount of material waste. These have been printed in stainless steel by means of selective laser melting (SLM) technique which consists of a high-energy laser beam that fuses a fi ne metal powder precisely distributed on a printing stage in a layer-by-layer fashion according to a predetermined design. [ 14 ] In one single fabrication process a series of electrodes of different sizes have been produced. The electrodes have then been functionalized by the electrochemical deposition of IrO 2 fi lms which conferred to the steel electrodes signifi cant capacitive properties, catalytic properties toward the oxygen evolution reaction (OER) and sensing properties toward proton concentration in solution (pH). Scanning electron microscopy combined with energy-dispersive X-ray (EDX) detectors were used to characterize the electrodes before and after the deposition of IrO 2 , prior the electrochemical testing for capacitive behavior and OER in alkaline solution and as potentiometric pH sensor.The use of such technology for electrochemical applications represents a breakthrough in on-site electrochemical device fabrication allowing the fabrication of specifi c electrode designs that can be tailored to facilitate specifi c functions and properties. Results and DiscussionIn this work, we intend to demonstrate the applicability of metal 3D printing to fabricate custom-made metal electrode of specifi c and desired shape to be used for electrochemical applications. As proof-of-concept, we designed a series of helical electrodes of different sizes also with the aim to test the range of sizes achievable with the printer employed. Helical 3D-Printed Metal Electrodes as Custom-Shaped 3D Platform for Electrochemical DevicesAdriano Ambrosi , * James Guo Sheng Moo , and Martin Pumera * 3D-printing represents an emerging technology that can revolutionize the way object and functional devices are fabricated. Here the use of metal 3D printing is demonstrated to fabricate bespoke electrochemical stainless steel electrodes that can be used as platform for different electrochemical applications ranging from electrochemical capacitors, oxygen evolution catalyst, and pH sensor by means of an effective and controlled deposition of IrO 2 films. The electrodes have been characterized by scanning electrode microscopy and energy dispersive X-ray spectroscopy before the electrochemical testing. Excellent pseudocapacitive as well as catalytic pr...

Synthetic autonomously moving nano and micromotors are in the forefront of nanotechnology. Different sizes of nano and micromotors have been prepared, but the systematic study of the influence of their sizes on motion is lacking. We synthesized different sizes of tubular micro/nanomotors by membrane template-assisted electrodeposition. The influence of dimensions on the dynamics of micro/nanotubes was studied at a significantly reduced scale than rolled-up microtubes, down to the nanometer regime. Both the geometric parameters and the chemical environment can affect the dynamics of micro/nanotubes. The bubble size and ejection frequency were investigated in correlation with the velocity of micro/nanotubes. The comparison between different sizes of micro/nanotubes showed that geometric parameters of micro/nanotubes will influence the velocity of micro/nanotubes at moderate fuel concentrations. Furthermore, it also affects the activity of micro/nanotubes at low fuel concentrations and imposes limitations on the velocity at very high fuel concentrations. Nanotubes with nanometer-sized openings need a higher concentration of H2O2 to be activated. Larger tubes can possess a higher absolute value of velocity than smaller tubes, but do not necessarily have a higher velocity by body lengths per unit time. Insight into bubble ejection/propulsion cycle is also provided. The results presented here provide important implications for the consideration of dimensions in the fabrication of tubular micro/nanomotors.

The rise of miniaturized artificial self-powered devices, demonstrating autonomous motion, has brought in new considerations from the environmental perspective. This review addresses the interplay between these nano/micro/macromotors and the environment, recent advances, and their applications in pollution management. Such self-propelled devices are able to actuate chemical energy into mechanical motion in situ, adding another powerful dimension towards solving environmental problems. Use of synthetic nano/micro/macromotors has demonstrated potential in environmental remediation, both in pollutant removal and contaminant degradation, owing to motion-induced mixing. At the same time, the chemical environment exerts influence on the locomotion of the motors. These sensitized self-powered devices demonstrate capabilities for being deployed as sensors and their chemotactic behaviors show efficacy to act as first responders towards a chemical leakage. Thus, the notion of a self-propelling entity also entails further investigation into its inherent toxicity and possible implications as a pollutant. Future challenges and outlook of the use of these miniaturized devices are discussed, with specific regard to the fields of environmental remediation and monitoring, as we move towards their wider acceptance. We believe that these tiny machines will stand up to the task as solutions for environmental sustainability in the 21st century.

The availability of drinking water is of utmost importance for the world population. Anthropogenic pollutants of water, such as heavy-metal ions, are major problems in water contamination. The toxicity assays used range from cell assays to animal tests. Herein, we replace biological toxicity assays, which use higher organisms, with artificial inorganic self-propelled microtubular robots. The viability and activity of these robots are negatively influenced by heavy metals, such as Pb(2+) , in a similar manner to that of live fish models. This allows the establishment of a lethal dose (LD50 ) of heavy metal for artificial inorganic microfish robots. The self-propelled microfish robots show specific response to Pb(2+) compared to other heavy metals, such as Cd(2+) , and can be used for selective determination of Pb(2+) in water. It is a first step towards replacing the biological toxicity assays with biomimetic inorganic autonomous robotic systems.

The miniaturization of energy storage microcapacitors to develop portable electronic devices has been of high recent interest. Here, microsupercapacitors microrobot is fabricated using membrane template‐assisted electrodeposition of WS2 nanoparticles (WS2NPs)/polyaniline (PANI) and platinum (Pt) layers. The microrobot navigates in the microchannel and attaches itself as part of the electrical circuit. The attached WS2NPs‐PANI/Pt microrobots enhance the capacitive behavior of the circuit significantly. The results presented in this work open the door for the development of smart and miniaturized functional micromotors that are able to self‐assemble to on‐demand circuits.