One-step formation of polymorphous sperm-like microswimmers by vortex turbulence-assisted microfluidics

Chemically active colloidal superstructures

Mimicking biological systems, artificial active colloidal motors that continuously dissipate energy can dynamically self-assemble to form active colloidal superstructures with specific spatial configurations and complex functionalities, which offers a promising pathway for developing new active soft matter materials with adaptability, self-repair, and reconfigurability. Beyond merely propelling their own motion, chemically driven colloidal motors can also induce phoretic effects and osmotic flows to affect the motion of neighboring colloidal motors through local fluid fields generated by chemical reactions, thereby achieving spontaneous chemical communication and promoting dynamic self-assembly between motors. This review summarizes the latest progress in the dynamic self-assembly of chemically driven colloidal motors, ranging from single chemically driven colloidal motors to chemically driven colloidal motors with passive colloidal particles and then to different chemically driven colloidal motors, ultimately forming active colloidal superstructures with complex dynamic behaviors. Not only are the interactions between chemically driven colloidal motors with different self-propulsion mechanisms and passive colloidal particles focused on, but also the communication behaviors between chemically driven colloidal motors are explored. We explain the fundamental physicochemical mechanisms that regulate the assembly behavior of chemically driven colloidal motors, propose general strategies for the controlled construction of active colloidal superstructures, and discuss the potential applications that may emerge from the directed dynamic self-assembly of these superstructures.

Bioinspired Soft Robots with Integrated Biological Motion Mechanisms and Rigid-Flexible Coupling Systems

The inherent flexibility, safety, and biocompatibility of soft robots show significant potential for intelligent biomedical engineering applications. However, the unique operating environments of soft robots, including both in vivo and in vitro conditions, necessitate highly flexible movement capabilities. Optimizing the structural design to enable multi-degree-of-freedom motions is crucial to realize the expansion and deepening of soft robots in this field. Inspired by shape-morphing organisms in nature, researchers have recently developed a variety of bioinspired soft robots (BSR) with morphing capabilities that can realize motions such as bending, twisting, and stretching/contracting. The shape-morphing of organisms is determined by their unique motion mechanisms. This work comprehensively reviews the structure and morphology of typical biological prototypes with different shape-morphing behaviors, motion mechanisms, design strategies of the deformable BSR, and their vast applications in current biomedical engineering. Finally, this review also provides valuable insights into the current challenges and future opportunities for BSR.

Bacteria Flagella-Mimicking Polymer Multilayer Magnetic Microrobots

Mass production of biomedical microrobots demands expensive and complex preparation techniques and versatile biocompatible materials. Learning from natural bacteria flagella, the study demonstrates a magnetic polymer multilayer cylindrical microrobot that bestows the controllable propulsion upon an external rotating magnetic field with uniform intensity. The magnetic microrobots are constructed by template-assisted layer-by-layer technique and subsequent functionalization of magnetic particles onto the large opening of the microrobots. Geometric variables of the polymer microrobots, such as the diameter and wall thickness, can be controlled by selection of porous template and layers of assembly. The microrobots perform controllable propulsion through the manipulation of magnetic field. The comparative analysis of the movement behavior reveals that the deformation of microrobots may be attributed to the propulsion upon rotating magnetic field, which is similar to that of natural bacteria. The influence of actuation and frequency on the velocity of the microrobots is studied. Such polymer multilayer magnetic microrobots may provide a novel concept to develop rapidly delivering drug therapeutic agents for diverse practical biomedical uses.

Machine Learning Assisted-Intelligent Lactic Acid Monitoring in Sweat Supported by a Perspiration-Driven Self-Powered Sensor

Lactic acid has aroused increasing attention due to its close association with serious diseases. A real-time, dynamic, and intelligent detection method is vital for sensitive detection of lactic acid. Here, a machine learning (ML)-assisted perspiration-driven self-powered sensor (PDS sensor) is fabricated using Ni-ZIF-8@lactate oxidase and pyruvate oxidase (Ni-ZIF-8@LOx&POx)/laser-induced graphene (LIG), bilirubin oxidase (BOD)/LIG, and a microchannel for highly sensitive and real-time monitoring of lactic acid in sweat. Driven by the oxidation reaction of lactic acid, PDS sensors exhibit excellent sensitivity, a wide detection range, good reproducibility, and excellent selectivity for lactic acid detection in sweat. When subjects with different body mass index (BMI) undergo aerobic or anaerobic exercise or maintain a sedentary state, PDS sensors can monitor lactic acid in sweat wirelessly and in real-time. Moreover, a ML algorithm was employed to assist PDS sensors to detect lactic acid in the subjects' sweat with a high prediction accuracy of 96.0%.

Design and batch fabrication of anisotropic microparticles toward small-scale robots using microfluidics: recent advances

Small-scale robots with shape anisotropy have garnered significant scientific interest due to their enhanced mobility and precise control in recent years. Traditionally, these miniature robots are manufactured using established techniques such as molding, 3D printing, and microfabrication. However, the advent of microfluidics in recent years has emerged as a promising manufacturing technology, capitalizing on the precise and dynamic manipulation of fluids at the microscale to fabricate various complex-shaped anisotropic particles. This offers a versatile and controlled platform, enabling the efficient fabrication of small-scale robots with tailored morphologies and advanced functionalities from the microfluidic-derived anisotropic microparticles at high throughput. This review highlights the recent advances in the microfluidic fabrication of anisotropic microparticles and their potential applications in small-scale robots. In this review, the term 'small-scale robots' broadly encompasses micromotors endowed with capabilities for locomotion and manipulation. Firstly, the fundamental strategies for liquid template formation and the methodologies for generating anisotropic microparticles within the microfluidic system are briefly introduced. Subsequently, the functionality of shape-anisotropic particles in forming components for small-scale robots and actuation mechanisms are emphasized. Attention is then directed towards the diverse applications of these microparticle-derived microrobots in a variety of fields, including pollution remediation, cell microcarriers, drug delivery, and biofilm eradication. Finally, we discuss future directions for the fabrication and development of miniature robots from microfluidics, shedding light on the evolving landscape of this field.