ETH Zurich magnetic microrobot

Overview

A drug-carrying capsule built to reach blood clots in the brain, with stroke as the first target. The sphere is a soluble gelatin gel holding zinc-doped iron oxide nanoparticles for magnetic steering and tantalum nanoparticles for X-ray visibility. A custom catheter, built on a commercial 7 Fr model, carries it into an artery or the spinal fluid. A small polymer gripper opens to release it. Two electromagnetic units around the head then steer it three ways. It can roll along the vessel wall, get pulled against the flow, or ride the flow while a gradient pushes it into the chosen branch, called in-flow navigation. At the target, a high-frequency field heats the nanoparticles, a process called magnetic hyperthermia, and the gel melts to release the drug.

The Science paper (Landers et al., November 2025) loaded the capsules with a clot-dissolving enzyme (rtPA), an antibiotic (ciprofloxacin) and a cancer drug (doxorubicin). In-flow steering hit the right branch in over 95% of tests, at flows up to 84 cm/s. In a silicone model of a patient's brain arteries, an rtPA capsule began dissolving a human blood clot within 7.5 minutes. In pigs the capsules stayed visible on X-ray as they were steered through the head arteries. In sheep they were guided through spinal fluid into a brain cavity. The vessel models are now sold by ETH spin-off Swiss Vascular. No human trials had started as of the November 2025 coverage, and no 2026 trial news was found.