Machining swarf formation–inspired fabrication of ferrofluidic helical miniature robots with multimodal locomotion capability

Magnetic helical robots (MHRs) have shown notable potential for targeted therapy. However, traditional fabrication methods are usually complex and expensive, and the prepared MHR's locomotion is monotonous with limited capacity. Here, we present a cost-effective, customizable, and scalable fabrication craft of MHR, via using bent needle tips to engrave helical structures onto polymethyl methacrylate substrates and incorporating nanoparticle alignment strategies to create ferrofluidic helical miniature robots (FHMRs) with cross-scale size scopes. We then propose strategic magnetic driving methods that enable FHMRs with five powerful motion modes for negotiating various application scenarios. Experimental results show that FHMRs can move flexibly and effectively simulate thrombus removal within a vascular model by integrating multiple motion modes. Furthermore, modified FHMRs can swiftly deliver drugs to targeted areas, with the capability for phased release on surfaces of wrinkled physiological tissues. These advancements highlight the considerable potential of FHMRs for future applications in the biomedical field.