STEOM, Explained: The French Implant Designed to Switch Off Sperm Flow

Published October 31, 2026 · Investigational · Not approved

On September 16, 2026, at a ceremony in Paris, a Lille project called STEOM won one of ten Grand Prix awards in France's national i-Lab innovation contest, worth €500,000, according to the French research ministry. French media have nicknamed it the "male IUD." STEOM is a medical device in development. It is investigational, it has not been tested in people, and it is not approved anywhere.

What STEOM is

The ministry describes STEOM as an implant for the vas deferens, the tubes that carry sperm: mechanical, hormone-free, designed to be reversible and to be placed in about 15 minutes. The University of Lille says it relies on micromechanical technology and is being developed by BeOm with the CHU de Lille (Lille's university hospital), the CIC-IT clinical investigation center and university labs, with support from the Eurasanté incubator. The idea came from Lille andrologist Dr. Julie Prasivoravong; her brother Dominique Prasivoravong leads the company being set up, according to actu.fr. A prototype was patented in 2025 [1].

How it's meant to work

The team's own shorthand is a faucet. "We like to say it's a tap," researcher Jessica Schiro told France 3. The device sits on the vas deferens and is designed to block sperm from passing through, rather than stopping the body from making sperm. Because it doesn't use hormones, the developers say it isn't meant to affect sperm production or libido [3]. That puts it in WHO's "sperm transport" category, alongside hydrogels like ADAM, RISUG and Plan A (see our injectable-race explainer). The difference is that STEOM is a mechanical device rather than a gel. These are design goals; none has been shown in a human study.

What the €500,000 is for

According to La Clé Publique, Dominique Prasivoravong says the money is meant to fund hiring, preclinical and then clinical testing, remaining technical hurdles, and regulatory, quality and manufacturing work. The outlet notes that the detailed budget and the exact milestone the grant should reach are not public. Grand Prix winners also get a year of support from Bpifrance, France's public investment bank, which runs the contest [4].

Where testing stands, and when humans might come

STEOM is in animal testing. France 3 reports that a first prototype is to be implanted in dogs, and La Clé Publique says the CIC-IT had announced the first preclinical tests for May 2026 with the University of Liège. Sources give different dates for a first human trial:

France 3: a first implantation in a man hoped for by 2030, in a clinical trial.
La Clé Publique: the CIC-IT mentions first clinical trials around 2031, depending on preclinical results, and calls this a team goal, not a fixed date.
actu.fr: the team hopes to start human testing by 2028 and to reach the market in 7 to 10 years, with 2033 mentioned as a possible earliest date if trials go well.

We'd treat all of these as hopes. Medical device timelines often slip, and the first real test is whether the animal data hold up.

Why it got attention in France

The ministry says the jury valued the project's social impact. France's health ministry also published a 2026–2030 sexual health roadmap on September 9 that aims to make no-scalpel vasectomy easier to get, which the STEOM team cites as a sign of demand for male methods [3][4]. For the bigger picture of what men say they'd use, see our look at the 14,000-man European survey.

The bottom line

STEOM is an early-stage idea with real backing and no human data. The questions that matter, whether it reliably blocks sperm, whether it can be removed without harming fertility, and whether it's safe long term, will only be answered in trials. STEOM is investigational and not approved. Track it alongside every other candidate on our status page.

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This article is news and education, not medical advice. No male contraceptive described here is approved. Get notified of updates.