The manufacturing process for FibroTend is based on an electrospinning technique.In its simplest form a polymer solution is passed through a nozzle which is subjected to a high voltage field. A cone of polymer will form on the outlet of the nozzle referred to as a Taylor cone. A jet of fibre is ejected from the cone which will split into hundreds of fibres in the sub-micron scale. These fibres are then manipulated to form an array of parallel fibres while simultaneously being stretched.
The process is robust and can accommodate most thermoplastics. Produced at room temperature, FibroTend requires no further thermal input. The fibres are streched whilst still in a gel-like state and can be stretched up to 800%.
The fibres produced by an electrospinning process contain a large degree of molecular chain alignment initially due to so called confinement. The polymer chain is further aligned as the fibres progress through the MTL process to form FibroTend.
These fibres exhibit higher tensile modulus compared to non-aligned fibres and results show a two fold increase in value.
FibroTend is produced in a range of fibre orientations from 0 to almost 90 degrees. A multi-layer laminate can be manufactured by overlaying fibres at designed orientations similar to an advanced fibre reinforced composite laminate.
The inherent properties of FibroTend, a highly aligned polymer chain with polarised atoms, exactly match the requirements for making piezoelectric film sensors. We have called this sensor TremoGen as it responds more efficiently to a bending force rather than a compressive force as is the case with ceramic based piezoelectric materials.
The most commonly used polymer for manufacturing piezoelectric film is Polyvinylidene Fluoride (PVDF).
The main requirements for PVDF to gain piezoelectric properties are the polymer chain alignment and the polerisation of the atoms to transform the polymer chain from the α to β phase.
FibroTend achieves these requirements as a matter of course and has enabled MTL to produce piezoelectric PVDF fibres. An array of FibroTend can form a sheet which is then sandwiched between suitable electrodes and over wrapped with a protective flexible and transparent laminate which also helps distribute the bending force uniformly over the entire sensor.
TremoGen is a flexible sensor capable of producing sufficient voltage to be used in many applications such as wearable technology, personal health monitoring devices and as standalone actuators. A typical TremoGen sheet thickness is 200 – 500 nanometres making it ideal for incorporation into textiles or applications that require a high degree of flexibility.
A biaxial FibroTend spun on a low gsm substrate can produce efficient filters. Unlike traditionally spun nanofibres that produce a mat of random fibres and relies on the build up of fibre layers to achieve high filtration efficiency, FibroTend can achieve the same performance through regular pore sizes akin to wire mesh.
The pore size can be regulated for a given particle size so that only one layer of biaxial FibroTend will be sufficient to achieve high filtration efficiency. This will enable thinner filters to be manufactured, minimising pressure drop as well as reducing material usage. These factors will contribute to a lower cost and higher efficiency filtration system.
The FibroTend can be functionalised to be an active filter and due to its inherently large surface area the active ingredients readily interact with contaminates.