A core–sheath fibre with pores that taper from 10 micrometres to under 3 detects carbon monoxide and temperature at once, and refuses to burn — a textile-integrated approach to early fire warning.

Most domestic fire detectors wait for one signal. A smoke alarm waits for particles; a heat detector waits for a temperature threshold. Each is reliable in its own failure mode and blind in the other, which is why kitchens set off smoke alarms and why smouldering fires can burn for a long time before a heat detector notices. A team working across Wuhan Textile University, Donghua University and the University of Southern Queensland has built a fibre that watches two signals simultaneously, and that can be woven into fabric.

The work, published in Nano-Micro Letters, describes a core–sheath fibre made by coaxial wet spinning — a process in which two materials are extruded together through concentric nozzles, so that one emerges as a continuous skin around the other. The core senses temperature. The sheath senses carbon monoxide. Neither function interferes with the other, because they are physically separated by design.

Pores that get smaller as they go in

The distinctive feature is in the sheath, and it is the reason the researchers describe the structure as biomimetic. The pores are not uniform. They measure more than 10 micrometres at the outer surface and taper to under 3 micrometres on the inside, producing a gradient that runs through the thickness of the skin.

The logic is the same logic that governs a lung or a leaf: wide openings at the surface admit gas quickly, while narrower channels further in increase the surface area available for the gas to interact with. Gas sensors are limited by how fast the target molecule can reach the sensing material and by how much sensing material it can touch once it arrives. A graded pore structure addresses both at once rather than trading one against the other.

The effect is measurable. The gradient raises the fibre’s carbon monoxide response by about 15 per cent compared with a fibre whose pores are uniform. That is a modest but real improvement attributable purely to geometry, with no change in the sensing chemistry — which makes it the kind of result that could in principle transfer to other gas sensors built the same way.

The numbers

For carbon monoxide, the fibre reports a sensitivity of 0.95 per cent per part per million, a detection limit of 10 ppm and a response time of 19.28 seconds. The temperature-sensing core, built from MXene — a family of two-dimensional transition metal carbides that conduct well and survive heat — operates between 50 and 300 °C with a Seebeck coefficient of 20.6 microvolts per kelvin and a linearity of R² = 0.99 across that range.

The Seebeck coefficient describes how much voltage a material generates per degree of temperature difference, which means the temperature sensing requires no power supply of its own: the heat itself produces the signal. Linearity of 0.99 across a 250-degree span is good, and it matters practically, because a sensor whose response curves unpredictably needs calibration at many points rather than two.

The temperature response also survived repeated bending, which is the test that separates a flexible sensor from a rigid one that happens to be thin. A fibre destined for clothing or upholstery will be flexed thousands of times.

It does not burn

A fire sensor that fails in a fire is of limited use, and this is where the fibre’s material choice pays off. Its limiting oxygen index is 41.5 per cent — meaning it will not sustain combustion unless the surrounding atmosphere is more than 41.5 per cent oxygen. Air is about 21 per cent. Materials above roughly 28 per cent are generally classed as flame-retardant; 41.5 per cent puts this fibre well into that territory.

In a wireless prototype, the researchers held an alcohol-lamp flame to the fibre and recorded an alarm in about three seconds. Carbon monoxide at 10 ppm was detected within 19 seconds. Signals were transmitted over Bluetooth or Wi-Fi, which is what makes the device a warning system rather than a laboratory measurement.

The three-second figure and the 19-second figure measure different things, and the gap between them is instructive. Heat arrives by radiation and convection, essentially at once. Carbon monoxide has to diffuse through the pore network to reach the sensing material, which takes time no matter how cleverly the pores are arranged. A dual-mode sensor gets the fast signal from one channel and the specific signal from the other.

Why carbon monoxide is the right gas

Carbon monoxide is produced by incomplete combustion, which is characteristic of smouldering and oxygen-starved fires — precisely the fires that kill people in their sleep and that a heat detector is slowest to catch. It is also the gas that does most of the killing: in residential fire deaths, carbon monoxide poisoning is a more common cause than burns. A sensor that detects it at 10 ppm is operating well below the concentrations that cause symptoms, which in adults begin to appear in the low hundreds of parts per million over hours of exposure.

Pairing that with temperature covers the other case. A fast-flaming fire produces heat immediately and may produce relatively little carbon monoxide early on. One channel catches each.

What the release leaves out

This release is unusually bare of the context that would let a reader judge the work. It contains no direct quotations from any of the authors, so none appear here. It lists no funding sources and no conflict-of-interest statement. It credits the research as “led by” three named professors — Hualing He, Siqi Huo and Zhicai Yu — without identifying a first or corresponding author, so the endnote below carries the paper title alone.

The technical gaps matter more. There is no information on selectivity: a carbon monoxide sensor that also responds to cooking vapours, cigarette smoke, alcohol or humidity would produce false alarms, and a laboratory test against an alcohol lamp does not address this. Nothing is reported about long-term stability, how the sensor behaves after weeks or months of exposure to ordinary air, or whether it drifts. Nor is there any account of what it would take to manufacture the fibre at textile scale, how it would be powered in a woven garment, or what it costs.

The release also carries a date inconsistency worth noting: it is dated 7 October 2026 while giving the paper’s publication date as 3 August 2026, two months earlier.

What the work establishes is a clean piece of materials engineering — a single fibre that reports two independent fire signals, resists burning, and bends without losing function. Whether it belongs in a wall or in a shirt is a question the paper does not have to answer yet.

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Notes

1. “Biomimetic Gradient Porous Core–Shell Fibers with Enhanced Gas Sensing for CO-Temperature Dual-Mode Early Fire Warning.” Nano-Micro Letters, 3 August 2026. DOI: 10.1007/s40820-026-02292-8.
2. Shanghai Jiao Tong University Journal Center. “Biomimetic gradient fiber enables dual-mode sensing for rapid and intelligent fire warning.” EurekAlert!, 7 October 2026. https://www.eurekalert.org/news-releases/1147108.