Researchers at a Swiss University have come up with a tiny, wire-free capsule that can be swallowed to print living materials directly inside the body.
Two academics at the École Polytechnique Fédérale in Lausanne (EPFL) have published a study detailing their work creating MEDS (Magnetic Endoluminal Deposition System), the world’s first tether-less, swallowable bioprinter capable of depositing tiny amounts of biological “ink” inside the stomach.
The pill-sized device, could mark a turning point in minimally invasive medicine, paving the way for minimally invasive tissue repair, haemorrhage control, and other regenerative applications where robotics, materials, and electronics converge to create precision devices that act inside the body.
Measuring just 6 millimetres across and 14 millimetres long, MEDS contains a spring-loaded plunger, a small bio-ink reservoir, and a miniature effector magnet (EM) encased in a biocompatible resin shell.
Unlike existing medical capsules that are connected to external wires or catheters for power and control, the tether-less device operates entirely without physical connections, relying instead on magnetic and optical signals to guide and trigger it.
In the MEDS ‘pill’, external actuator magnets (AMs) mounted on robotic arms provide precise positioning, while a pulse of NIR light activates a precision mechanical plunger to release what the scientists calls ‘bio-ink’ – a gel-like material often used in tissue engineering which contains living cells and nutrients.
“By removing wires and batteries, we can control the device precisely from outside the body,” said Sanjay Manoharan, Doctoral Assistant at EPFL’s Laboratory for Advanced Fabrication Technologies. “This greatly simplifies the design and makes it far less invasive.”
Manoharan says that the capsule moves along the stomach wall using a novel stick-slip motion, allowing it to crawl and reposition over curved and uneven surfaces while keeping its bio-ink stream steady. The AM-EM configuration allows six degrees of freedom — including pitch, yaw, and roll — giving the capsule freedom that traditional tethered endoscopic tools cannot match.
“Tethered devices are limited by cables and sheaths. Our system can move more freely, reaching areas that were previously hard to access,” added Vivek Subramanian, co-author and supervisor at EPFL.
‘Dispense and daub’
To deposit bio-ink, MEDS uses a “dispense-and-daub” method where the capsule drops small volumes of bio-ink and then spreads them along a defined path. A specially designed barbed magnet tip helps smooth and merge the drops into a uniform layer.
According to the paper, the device successfully printed over ex vivo ulcers, artificial bleeding sites, and curved tissue surfaces. Tests found it could retain 73% of its mass under simulated stomach conditions, and even support living human gastric cells.
During testing, the scientists relied on real-time X-ray imaging for guidance but used pre-programmed magnet paths to ensure repeatable, precise motion. Flow rates, nozzle geometry, and gel viscosity were characterised using microfluidic sensors, helping the engineers fine-tune the system.
“From an engineering perspective, the innovation is how we integrate magnetic steering, NIR-triggered extrusion, and mechanical design in a device that weighs just 28 milligrams,” said Manoharan.
The researchers tested the device using live rabbits, demonstrating the full process: swallowing, magnetic steering to target areas, NIR-triggered deposition, patterning, and retrieval. They reported that the capsule moved reliably even in the variable environment of the stomach, showing that untethered micro-devices could work safely in living systems.
“Watching the capsule deposit bio-ink in a live animal was a key milestone — it proves this approach can work in real physiology,” said Subramanian.
The research highlights the growing convergence of miniaturised electronics, robotics, and materials engineering in medicine. Magnetic control replaces onboard electronics, NIR-triggered shape-memory polymers replace mechanical actuators, and surface-mediated navigation allows precision without wires. For engineers in robotics or electronics, the system shows how magnetic actuation, sensor feedback, and micro-scale design can enable completely new classes of medical tools.
“Our work shows that a pill can do more than deliver drugs — it can actively build tissue where it’s needed,” added Manoharan.
