A compostable industrial earplug that production-line X-ray inspection can still find, with no embedded metal.
From the Greek sigē (silence) + phylax (guardian).
Plants need hearing protection that won't pollute and won't contaminate product. The earplug industry could deliver one or the other — never both at once.
Bio-foam and mycelium plugs return to the earth — but carry no detection feature. A lost plug in a food or drug batch goes unseen.
Detectable plugs work by embedding a steel bead or metal particles — exactly what makes them impossible to compost, and unusable where metal is banned.
Detectability is carried by a non-metallic, compost-compatible radiographic contrast built into the material itself — preferably covalently-bound iodine that gives X-ray density without a restricted heavy-metal filler. The plug shows up under inspection in use, then disintegrates without leaving metal behind.
The detection function lives in the whole body of the plug — not in a single bead — so even a sheared fragment stays findable.
A biodegradable polymer or cellulosic matrix — designed to meet recognized compostability standards.
Covalently-bound iodine confers radiographic density — detectable by inspection equipment, with no embedded metal.
Contrast is dispersed throughout, so a fragment as small as ~2 mm still trips rejection.
Disintegrates under composting — with an optional thermal trigger set well above any in-use temperature.
Production lines catch foreign objects two ways. Sigephylax is engineered around the one that doesn't require metal — and that's the whole trick.
X-ray inspection reads density contrast. A constituent built from high-atomic-number atoms attenuates X-rays strongly — so the plug shows up as a clear shadow, the same way a bone does, without containing any metal.
Metal detectors sense a disturbance in an electromagnetic field caused by conductive or magnetic material. A compostable, metal-free plug has none — so a metal-only line can't see it. That's exactly why the industry resorted to embedded steel. Sigephylax targets X-ray lines instead, or adds a biodegradable conductive carbon for dual-mode lines.
Iodine is dense enough to cast an X-ray shadow but, covalently bound into the matrix, it isn't a free heavy metal. The plug is visible in use and leaves nothing restricted behind when it breaks down.
The obvious way to make plastic X-ray-visible is a dense mineral like barium or bismuth. But compost standards — EN 13432, ASTM D6400 — cap heavy metals and ecotoxicity. The very thing that makes a plug detectable is what fails certification. Bound iodine is the way around it.
Because the contrast is dispersed through the whole body rather than parked in one bead, a plug sheared in a mixer or auger still rejects — every fragment carries its share of the signal.
A dislodged plug — or a piece of one — enters the product on the belt. X-ray inspection reads its density contrast and diverts the batch. No metal detector required.
Illustrative simulation of density-based detection.
Every figure below is a design target for the platform, not a measured or certified result. Validation comes before any of these becomes a claim.
Slow-recovery compostable foam for high-noise, single-use settings.
Triple-flange seal that earns attenuation from geometry as well as material.
For intermittent noise and quick on-off use on the floor.
Detectable cotton-fiber cord — so a severed cord rejects too.
HACCP / FSMA foreign-material control.
Sterile and inspected production.
Fill lines with contamination limits.
Plastic- and metal-free; repulpable.
High-noise plants cutting plastic waste.
| Metal-detectable plug | Compostable plug | Sigephylax | |
|---|---|---|---|
| Detectable on the line | Yes | No | Yes |
| Compostable at end of life | No | Yes | Yes |
| No embedded metal | No | Yes | Yes |
| Fits plastic-/metal-free lines | No | Partly | Yes |
| Detectable even as a fragment | Bead only | No | Throughout |
Sigephylax is early. Here's the path from a drafted provisional to plugs on a line — and the exact step we're on.
42 claims across composition, device, methods, and system.
DoneTargeted at the detectable-PPE + biodegradable-radiopacifier intersection.
In progressFoam feasibility, attenuation, and a validated minimum fragment size.
NextFollowing a clean search and validated data.
PlannedWith plants already running X-ray inspection.
PlannedComposition, device, methods, and system.
Independent claim families across the four-way intersection.
Single-inventor provisional filing posture.
Affiliated holding under the HeOntotita group.
Sigephylax is at the provisional-patent stage. Stated performance characteristics — attenuation, detectable fragment size, and compostability — are design targets pending laboratory validation and certification, not measured or certified results. A professional prior-art and freedom-to-operate search precedes any non-provisional filing.
Yes — on X-ray inspection lines, which read density rather than magnetism. The contrast comes from high-atomic-number atoms bound into the material. For lines that run only metal detectors, a dual-mode variant adds a biodegradable conductive carbon.
It does, if you use a loose mineral filler like barium or bismuth — those run into the heavy-metal limits in EN 13432 and ASTM D6400. That's the whole reason the preferred design uses covalently-bound iodine, which delivers density without a restricted free metal.
The target is an NRR of at least 25 dB, and at least 30 dB in the flanged form. These are design goals pending laboratory validation, not certified ratings yet.
That's a lead use case. The pulp-and-paper variant is free of both plastic and metal, repulpable, and supplied in film-free paper packaging — compatible with environments that prohibit plastic contaminants.
Not yet. The technology is at the provisional-patent stage. We're scoping pilots with facilities that already run X-ray inspection — reach out if that's you.
Sigephylax is a HeOntotita-affiliated venture. A provisional application has been drafted; a non-provisional follows validation and a freedom-to-operate search.
We're looking for plants that run X-ray inspection and want to cut earplug waste without losing detectability.
