Cancer remains a tough challenge in modern medicine, affecting millions of lives each year. While clinical trials and research continue to advance, innovative approaches are essential to overcome the persistent challenges in cancer treatment. Millirobots are tiny machines designed to perform complex tasks inside the human body. These miniature devices have garnered significant attention for their potential to revolutionize medical procedures, particularly in the precise delivery of cancer treatments. However, ensuring their reliability and controllability remains a critical hurdle.

Traditional methods for creating microrobots, such as three-dimensional laser lithography, glancing angle deposition, biotemplates, laser ablation, and origami-based self-scrolling, have achieved some success. Yet, these techniques often suffer from low production throughput and material density issues, which can impede the millirobots' movement and accuracy. To tackle these limitations, our recent study introduces a innovative approach that leverages the unique properties of laser-induced graphene (LIG) to efficiently fabricate high-performance millirobots.

Our innovative LIG process utilizes beam shaping and defocusing to generate triangular laser spots that create a sloped intensity profile. This profile enables the local conversion of polymer surfaces into graphene, inducing uneven gas fluxes that cause the graphene sheets to twist into helical configurations as they peel off the substrate. The result is a millirobot scaffold that is both lightweight and hydrophobic, crucial for efficient movement and minimal drift in liquid environments. By coating these graphene-based structures with nickel, we harness magnetic guidance to achieve remarkable locomotion speed and precise trajectory tracking. These millirobots exhibit near-zero deviation from their programmed paths, a significant improvement over existing models. Additionally, they are capable of binding anticancer drugs through various interactions, including π–π stacking, electrostatic, and hydrophobic interactions. Controlled drug release is facilitated by near-infrared irradiation, ensuring deep tissue penetration and minimal organ damage.

We demonstrated the effectiveness of these graphene helical (GH) millirobots using gastric cancer drug delivery as a test case. Our findings show that GH millirobots excel in long-distance locomotion and targeted drug delivery within physiological environments. This research highlights the potential of GH millirobot technology to meet the demanding requirements of cancer treatment, offering superior performance, versatility, scalability, and cost-effectiveness.

Our study paves the way for large-scale production of millirobots, with a remarkable fabrication rate of 77 scaffolds per second. This high-throughput capability is a critical step towards the widespread deployment of millirobots in clinical settings, bringing us closer to a future where cancer treatment is more precise, effective, and accessible.

Figure 1. Design of and process for producing porous helical laser-induced graphene sheets. These graphene sheets with porous and dimensionally adjustable features. Then use of GH millirobots for therapeutic drug delivery.