Micro-/nanoscale robotics for chemical and biological sensing.

The field of micro-/nanorobotics has attracted extensive interest from a variety of research communities and witnessed enormous progress in a broad array of applications ranging from basic research to global healthcare and to environmental remediation and protection. In particular, micro-/nanoscale robots provide an enabling platform for the development of next-generation chemical and biological sensing modalities, owing to their unique advantages as programmable, self-sustainable, and/or autonomous mobile carriers to accommodate and promote physical and chemical processes. In this review, we intend to provide an overview of the state-of-the-art development in this area and share our perspective in the future trend. This review starts with a general introduction of micro-/nanorobotics and the commonly used methods for propulsion of micro-/nanorobots in solution, along with the commonly used methods in their fabrication. Next, we comprehensively summarize the current status of the micro/nanorobotic research in relevance to chemical and biological sensing (e.g., motion-based sensing, optical sensing, and electrochemical sensing). Following that, we provide an overview of the primary challenges currently faced in the micro-/nanorobotic research. Finally, we conclude this review by providing our perspective detailing the future application of soft robotics in chemical and biological sensing.

Micro-/Nanostructured Interface for Liquid Manipulation and Its Applications.

Understanding the relationship between liquid manipulation and micro-/nanostructured interfaces has gained much attention due to the wide potential applications in many fields, such as chemical and biomedical assays, environmental protection, industry, and even daily life. Much work has been done to construct various materials with interfacial liquid manipulation abilities, leading to a range of interesting applications. Herein, different fabrication methods from the top-down approach to the bottom-up approach and subsequent surface modifications of micro-/nanostructured interfaces are first introduced. Then, interactions between the surface and liquid, including liquid wetting, liquid transportation, and a number of corresponding models, together with the definition of hydrophilic/hydrophobic, oleophilic/olephobic, the definition and mechanism of superwetting, including superhydrophobicity, superhydrophilicity, and superoleophobicity, are presented. The micro-/nanostructured interface, with major applications in self-cleaning, antifogging, anti-icing, anticorrosion, drag-reduction, oil-water separation, water collection, droplet (micro)array, and surface-directed liquid transport, is summarized, and the mechanisms underlying each application are discussed. Finally, the remaining challenges and future perspectives in this area are included.

Efficient isolation and sensitive quantification of extracellular vesicles based on an integrated ExoID-Chip using photonic crystals.

Extracellular vesicles (EVs), involved in many diseases and pathophysiological processes, have emerged as potential biomarkers for cancer diagnosis. However, efficient isolation and detection of EVs still remain challenging. Here, we report an integrated chip for isolation of EVs with a double-filtration unit and ultrasensitive detection using photonic crystal (PC) nanostructure. Nanofiltration membranes were integrated into the device to isolate and enrich the EVs of 20-200 nm in size based on size-exclusion. Then, CD63 aptamers were used to combine the EVs on the nanofiltration membrane with a pore size of 20 nm, and excess aptamers passed through the membrane to bind with CD63 immobilized on the PC nanostructure. Benefitting from the fluorescence enhancement effect of the PC nanostructure in competition assays, the EVs could be quantified sensitively by analyzing the concentration of excess aptamers. Due to the high sensitivity, the limit of detection was as low as 8.9 × 103 EVs per mL with a low sample consumption of only 20 µL. Furthermore, serum samples from breast cancer patients and healthy donors could be successfully distinguished. Thus, this microfluidic chip provides an effective method for pre-screening of cancer in clinical samples.