Interest in untethered mini and micro-robots has shown a significant increase lately, especially magneto-responsive swimmers. In this study, a soft sub-millimeter sized swimmer and a magnetic actuation system was developed. An extrusion-based 3D printer was used to form swimmers with three different types of magnetic content, Fe micro flakes and nanoparticles, and Nd-Fe-B micro flakes, were incorporated into polymeric bounder material. Using milli- and micro-swimmers in biological environments demands the use of cyto-compatible materials that would disguise the magnetic materials from the immune system. In this study, particles were encapsulated in a gelatin-alginate-cellulose based hydrogel. Next, these microswimmers were steered along a path via the magnetic gradient created by a custom-made electromagnetic system. The base of the electromagnetic system was designed using a CAD computer program and three dimensionally (3D)-printed. Consisting of four independent solenoids, each two controlling the movement on an axis, the system was designed to move the microswimmers in a certain path. The solenoids were controlled by Arduino microcontroller board. The electrical current applied to the electromagnetic device in all the trials was 2 amperes, which generates a magnetic field in between 100 to 376 Gauss throughout the experiment area. Thus, a magnetic gradient from the center to the pole of the solenoid was established. The magnetic and chemical behavior of these materials were compared based on their magnetic responsiveness and 3d printability. Developed magneto-responsive microswimmers could be used in biomedical robotics and drug delivery applications.

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Trapping/separating bio-entities via magnetic field gradients created a vast number of possibilities to develop biosensors for the early detection of diseases without the need for expensive equipment or physician/lab technicians. Thus, opening a window for at-home disposable rapid test kits. In the scope of the current work, an innovative and cost-effective technique to form well-organized arrays of Nd–Fe–B patterns was successfully developed. High aspect ratio Nd–Fe–B flakes were synthesized by surfactant-assisted ball milling technique. Nd–Fe–B flakes were distributed and patterned into a PDMS matrix by the aforementioned technique. A microfluidic channel was integrated on the fabricated Nd–Fe–B/PDMS patch with a high magnetic field gradient to form a microfluidic device. Fe nanoparticles, suspended in hexane, were flowed through the microfluidic channel, and trapping of the magnetic nanoparticles was observed. More experiments would be needed to quantitatively study efficiency. Ergo, the microfluidic device with high trapping efficiency was developed. The established technique has the potential to outperform the precedents in trapping efficiency, cost, and ease of production. The developed device could be integrated into disposable test kits for the early detection of various diseases.