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Magnetic millirobots deliver drugs directly to a beating heart

Magnetic millirobots deliver drugs directly to a beating heart

New Capabilities

Johns Hopkins engineers aim to replace weeks of IV antibiotics and risky open-heart surgery for heart infections

October 14th, 2026: Researchers explore cancer applications for millirobots

Overview

Updated Oct 26

Johns Hopkins University engineers built a pair of magnetic robots the size of a pencil tip that are designed to travel through the bloodstream and put antibiotics directly on infected heart tissue. The robots carry no batteries or motors; coils outside the body, working on the same principle as an MRI machine, steer them. If it works in patients, the team says the procedure could take under an hour.

The aim is to replace the standard treatment for infective endocarditis, an infection of the heart's lining or valves: four to six weeks of IV antibiotics that often fails, with risky open-heart surgery as the fallback. In lab tests the robots crossed a heart phantom under simulated pulsing flow, docked all 15 times, undocked 13 of 13 times and released 22 microliters of blue dye over three hours. No infection was treated and no living heart has been tested yet.

Why it matters

A month of IV antibiotics for a heart infection could become one hour-long procedure, with no open-heart surgery.

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Key Indicators

66.7%
Tissue penetration force reduction
Barbed needle module cut the force needed to anchor in cardiac tissue-mimicking gel.
100%
Magnetic docking success rate
Drug module docked with the needle module on all 15 attempts in the heart phantom.
93%
Undocking success rate
Drug module released on demand in 12 of 13 attempts in the heart phantom.
22 µL
Payload delivered over 180 min
Drug module released 22 microliters of liquid, in tests run with dye rather than an antibiotic.

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People Involved

Axel Krieger
Axel Krieger
Senior author; head, Intelligent Medical Robotic Systems and Equipment Lab, Johns Hopkins University
Leading the millirobot research team; exploring cancer applications
 Anuruddha Bhattacharjee
Anuruddha Bhattacharjee
First author; assistant professor, University of Alabama at Birmingham
Former Johns Hopkins postdoctoral fellow

Organizations Involved

Johns Hopkins University
Johns Hopkins University
Research university
Research institution where the millirobots were developed

The Baltimore-based research university where the millirobots were designed, built, and tested.
University of Alabama at Birmingham
University of Alabama at Birmingham
University
Bhattacharjee's current institution

The academic home of first author Anuruddha Bhattacharjee.

Timeline

2 events Latest: October 14th, 2026 · 4 weeks ago

  1. Researchers explore cancer applications for millirobots

    Latest Research announcement

    Krieger and Bhattacharjee told Inside Precision Medicine the platform could be adapted to deliver chemotherapy to hard-to-reach liver, pancreas, or brain tumors. No cancer models have been tested.

  2. Johns Hopkins announces magnetic millirobots for cardiac drug delivery

    Research announcement

    Engineers unveiled a two-robot system that delivers antibiotics directly to infected heart tissue. Study published in Advanced Materials Technologies.

Scenarios

1

Millirobots pass dynamic beating-heart tests

Likely Resolves by Q2 2027

Discussed by: The Johns Hopkins research team

The team's next announced step is testing in phantom hearts that mimic the muscle contraction and beating motion of a real heart. If the robots navigate, dock, and deliver drugs under those conditions, and later in living animal models, the technology moves one step closer to clinical use.

2

Human trials begin for targeted cardiac drug delivery

Possible Resolves by End of 2028

Discussed by: The research team; NSF-funded program

If phantom and animal tests succeed, the team would seek regulatory approval and begin human trials. A first-in-human study would test whether the robots can be injected through a standard IV line, guided magnetically to the heart, and safely retrieved in living patients.

3

Millirobots stall at the bench; clinical path unclear

Possible Resolves by End of 2028

Discussed by: Skeptics of early-stage implantable robotics

The technology could fail to advance beyond phantom and ex vivo tests. Open challenges include scaling to a living beating heart, ensuring safe retrieval of the drug module, and winning regulatory approval for a magnetically controlled device inside the bloodstream.

4

Millirobots adapted to deliver cancer drugs directly to tumors

Possible

Discussed by: Krieger and Bhattacharjee, in interviews with Inside Precision Medicine

The researchers say the platform could be adapted for hard-to-reach tumors in the liver, pancreas, or brain, delivering repeated doses or combinations of drugs locally. No cancer models have been tested; the team says robots would need adjustments to size, structure, and drug release.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

2000s

Stereotaxis magnetic navigation (2000s)

Stereotaxis developed catheter systems steered by external magnets to treat heart arrhythmias, eliminating the need for manual catheter manipulation inside the heart.

Then

Cardiologists gained a way to guide flexible catheters to precise spots in the heart using magnetic fields.

Now

External magnetic steering of cardiac instruments became an established clinical tool, though it still relies on rigid catheters threaded through blood vessels.

Why this matters now

The millirobots use the same principle of external magnetic guidance but in a free-floating, untethered form, far smaller than any catheter-based system.

2001

Capsule endoscopy / PillCam (2001)

The PillCam, a pill-sized camera, became the first ingestible capsule to travel the gastrointestinal tract and transmit images wirelessly, approved for use in the early 2000s.

Then

Doctors gained a non-invasive way to inspect the small intestine without sedation or scopes.

Now

It proved miniature untethered devices could safely travel inside the human body, opening the field of ingestible and injectable medical devices.

Why this matters now

The millirobots extend that principle — but unlike the passively drifting PillCam, they are actively steered and can dock, deliver a drug over hours, and be replaced.

Sources

(9)
+3
Johns Hopkins University Hub Advanced Materials Technologies heise online Forbes / Yahoo Tech The Engineer Inside Precision Medicine Johns Hopkins Technology Ventures Johns Hopkins Data Science and AI Institute TechNews