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A new speed and scale for fibre development

A “Moore’s Law for fibres”, in which their applications multiply rapidly in the next few years as technologies get smaller, is foreseen by Professor Yoel Fink, the MIT professor of materials science and electrical engineering and CEO of AFFOA – Advanced Functional Fibers of America.

Moore’s Law was the observation made back in 1965 by Gordon Moore, co-founder of Intel, that the number of transistors per square inch on integrated circuits had doubled every year since the integrated circuit was invented. Moore predicted that this trend, allowing the ongoing miniaturisation of technologies, would continue for the foreseeable future.

He turned out to be right, and Fink believes the same is now happening in fibres.

“The fabrics we wear have remained functionally unchanged for thousands of years, but recent breakthroughs in fibre materials and manufacturing processes will soon allow us to design and wear fabrics that see, hear, sense, communicate, store and convert energy, regulate temperature, monitor health and change colour,” he says, adding that fibres are primarily a single material but nothing that functions is a single material.

“The magic number is three, to turn fibres into semiconductors – typically consisting of separate filaments acting as insulators, conductors and semiconductors. These will turn fabrics into prime real estate.”


Nanofibres

If this seems a little unlikely, consider the impact that nanotechnology is already having on materials science and the miniaturisation of fibre processing.

Bryan Haynes of Kimberly-Clark has famously observed that a sugar cube of polypropylene with sides of 1.58cm, weighing 3.5 grams, will suffice for the production of 15-micron spunbond fibres stretching some 14 miles. The same amount of polypropylene employed to make 3-micron meltblown fibres, meanwhile, results in 350 miles of fibre.

That same sugar lump employed to make 300-nanometre nanofibres, would result in enough material to stretch 35,000 miles, although how to produce these fibres cost-effectively and then turn them into nonwovens on a mass scale remains the million-dollar question.


SpinCare

One example of the acceleration of miniaturisation is SpinCare, the latest electrospinning technology which has just been launched by Nanomedic of Israel.

This portable bedside device enables immediate wound care treatment through the creation of customised nanofibrous dressings based on a patient’s wound condition. The dressings are fine-tuneable to surfaces, shapes, thicknesses, skin sites and the areas to be covered. They can be applied from a short distance, eliminating contact between the caregiver and the wound, reducing the potential of infection.

“This technology enhances the inherent characteristics of the electrospun nanofibres, mimicking the structure of the body tissue and as a result providing an excellent medium for tissue integration and regeneration and facilitating the body healing process,” says Professor Josef Halik, Director of Plastic and Reconstruction Surgery and The National Care Burn Centre in Shelpa, Israel, who has been working with the SpinCare technology.

SpinCare is in effect the smallest commercially-available nonwoven manufacturing machine.


Semiconductors

AFFOA came into existence in April 2016 after winning the contract to run a US government-funded National Network for Manufacturing Innovation (NNMI) Institute focused on technical textiles.
With total funding of some $317 million for its first five years of existence, AFFOA is a partnership involving 72 companies, 32 universities, 25 start-ups and five state government and regional organisations across the USA.

Among key developments reported by AFFOA and MIT are the embedding during 2018, of high-speed optoelectronic semiconductor devices, including light-emitting diodes (LEDs) and diode photodetectors, into fibres.

Optical fibres have been traditionally produced by making a cylindrical preform which is essentially a scaled-up model of the fibre, then heating it. The softened material is then drawn or pulled downward under tension and the resulting fibre is collected on a spool.

The key breakthrough for producing these new fibres was to add light-emitting semiconductor diodes the size of a grain of sand, and a pair of copper wires a fraction of a hair’s width to the preform. When heated in a furnace during the fibre-drawing process, the polymer preform partially liquifies, forming a long fibre with the diodes lined up along its centre and connected by the copper wires.

The solid components were two types of electrical diodes made using standard microchip technology – light-emitting diodes (LEDs) and photo-sensing diodes.

The resulting fibres have already been integrated into fabrics and can withstand ten domestic washing cycles.

Fink says the first commercial products incorporating this technology are already near to reaching the marketplace.

“Such rapid lab-to-market development was a key part of the reason for creating an academic-industry-government collaborative such as AFFOA,” he says. “These initial applications will be specialised products involving communications and safety and we are now in the process of transitioning the technology to domestic manufacturers and industry at an unprecedented speed and scale.”

 


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