Reprogrammable Magnetic Soft Actuators with Microfluidic Functional Modules via Pixel-Assembly.

Magnetic soft actuators and robots have attracted considerable attention in biomedical applications due to their speedy response, programmability, and biocompatibility. Despite recent advancements, the fabrication process of magnetic actuators and the reprogramming approach of their magnetization profiles continue to pose challenges. Here, a facile fabrication strategy is reported based on arrangements and distributions of reusable magnetic pixels on silicone substrates, allowing for various magnetic actuators with customizable architectures, arbitrary magnetization profiles, and integration of microfluidic technology. This approach enables intricate configurations with decent deformability and programmability, as well as biomimetic movements involving grasping, swimming, and wriggling in response to magnetic actuation. Moreover, microfluidic functional modules are integrated for various purposes, such as on/off valve control, curvature adjustment, fluid mixing, dynamic microfluidic architecture, and liquid delivery robot. The proposed method fulfills the requirements of low-cost, rapid, and simplified preparation of magnetic actuators, since it eliminates the need to sustain pre-defined deformations during the magnetization process or to employ laser heating or other stimulation for reprogramming the magnetization profile. Consequently, it is envisioned that magnetic actuators fabricated via pixel-assembly will have broad prospects in microfluidics and biomedical applications.

Full integration of nucleic acid extraction and detection into a centrifugal microfluidic chip employing chitosan-modified microspheres.

Microfluidic devices especially centrifugal ones have attracted great attention in the nucleic acid testing field, due to their automation, high efficiency, and simple operation. In which, nucleic acid extraction is the basic step, laying a foundation for the downstream amplification and detection procedures. Therefore, the integration of nucleic acid extraction on the chip is expected to achieve cost-efficiency, high-speed automation, diagnostic accuracy, and reaction robustness with the respect to real-time detection. In this work, we employ chitosan-modified magnetic microspheres for pH-induced nucleic acid extraction and integrate this approach into a centrifugal microfluidic chip. The microfluidic system comprises cell lysis, nucleic acids capture and release, isothermal amplification, and real-time fluorescence detection, which is manipulated by centrifugal force and magnetic control. The system exhibits comparable extraction and detection performance in respect of acceptable nucleic acid concentration and purity, high detection specificity and stability, as well as fast detection duration. These efforts to improve the integrated microfluidic detection chip could benefit the portable, efficient and simple nucleic acid diagnosis, especially under the resource-limited circumstance.