Magnetically actuated microrobots showed increasing potential in various fields, especially in the biomedical area, such as invasive surgery, targeted cargo delivery, and treatment. However, it remains a challenge to incorporate biocompatible natural polymers that are favorable for practical biomedical applications. In this work, bilayer magnetic microrobots with an achiral planar design were fabricated using a biocompatible natural polymer and Fe₃O₄ nanoparticles through the photolithography by applying the layer-by-layer method. The microrobots consisted of a magnetic bottom layer and a photo-crosslinked chitosan top layer. The SEM results showed that the microrobot processed the L-shaped planar structure with the average width, length, and thickness of 99.18 ± 5.11 μm, 189.56 ± 11.37 μm, and 23.56 ± 4.08 μm, respectively. Moreover, microrobots actuated using a three-dimensional (3D) Helmholtz coil system was characterized and reached up to an average maximum velocity of 325.30 μm/s and a step-out frequency of 14 Hz. Furthermore, the microrobots exhibited excellent cell biocompatibility towards L929 cells in the CCK-8 assay. Therefore, the development of bi-layered chitosan-based microrobots offers a general solution for using magnetic microrobots in biomedical applications by providing an easy-to-fabricate, highly mobile microrobotic platform with the incorporation of biocompatible natural polymers for enhanced biocompatibility.

Long-acting oral delivery of macromolecular therapeutics remains difficult, as most oral delivery devices focus on improving gastrointestinal absorption but do not adequately address sustained drug release and frequent dosing. In parallel, many gastric-retentive systems rely on nondegradable structural components, raising concerns regarding retained-device burden and postuse medical waste. Here, we report a biodegradable oral capsule device for long-lasting drug delivery, termed the sustainable gastric self-triggered device (SGSTD), inspired by the stinging mechanism of Apis mellifera . After reaching the stomach, SGSTD autonomously deploys a biodegradable barbed drug-loaded needle into the gastric wall, while the remaining carrier body is subsequently excreted, establishing a bioinspired “deploy-and-separate” strategy for long-acting gastric delivery. The embedded needle enables microchannel-mediated sustained release, with structurally tunable release behavior. Ex vivo and in vivo porcine studies confirmed gastric deployment, tissue retention, systemic safety, and localized tissue repair around the insertion region. In vivo, SGSTD maintained insulin delivery for over 7 days, achieving a relative bioavailability of 63.8%, approximately 17.2-fold higher than conventional oral administration. SGSTD is cost-effective, scalable, and composed of biodegradable materials, providing a sustainable strategy for long-acting oral biologics delivery.

A simple terahertz oscillator with corrugated cylindrical waveguide is presented in this paper. Using the simple unified theory, the beam-wave interactions are analyzed in the corrugated periodic metal slow-wave structure (SWS).