Ceramic SHaping: extrusion of glAss Preforms for new fibres in hEalthcare (SHAPE)

Ceramic SHaping: extrusion of glAss Preforms for new fibres in hEalthcare (SHAPE)


The Aim of this Project is to achieve unprecedented advances in novel glass extrusion in order to make brand new shapes of glass preforms. These preforms are needed for drawing to next-generation structured glass fibres for two targeted healthcare applications - bioimplant glass fibre for therapeutics and MIR (mid-infrared) glass fibre lasers for cancer detection.

1. Glass extrusion

What is glass extrusion? Heat glass above its glass transition temperature (Tg) and a viscous liquid forms. This liquid has treacle-like consistency and can be shaped by forcing it through a shaped metal die. For instance, a die with a hole
produces a rod-shaped extrudate. The extruded rod is allowed to cool, and stiffens at Tg to form a glass-rod preform, which is taken to a draw tower and, in a separate operation, drawn to form glass fibre of the ~ diameter of a human hair.

Co-extrusion, through the hole in the die, of two glass billets of different glass composition, but with matched thermal properties, forms a glass-rod preform with an internal core of different glass through it. Along part of the preform length, the internal core of glass occupies approx. constant 85 % of the diameter. When this is drawn to fibre, the fibre similarly has a large core of glass occupying 85 % of the diameter. The core/cladding interface is excellent optical quality, having mated during the extrusion itself. However, only 20% of the extruded rod preform is usable, as the core inside the rest of the preform is too tapered.

Extrusion through a spider-die can produce a glass preform in the shape of a small-orificed tube. If a cane of different glass is now threaded through this tube, this whole can be drawn to fibre with a small core running through it and occupying less than ~ 20 % of the fibre diameter. Such small core fibre is vital to achieve fibre lasing. However, this processing route makes inferior optical quality core/cladding interfaces and can take several weeks.


2. MIR fibre

This Project will enable straightforward manufacture of high quality small-core fibre vital for MIR-glass fibre lasers. We will extrude small-core glass-rod preforms with core less than or equal to 20 % diameter, constant over least 50 % of the preform, with core/cladding mating during extrusion to give excellent optical quality of the core/cladding interface. To achieve this breakthrough, we will invoke, for the first time, extrusion of pre-shaped glass billets, and also indirect glass extrusion - overlooked since its invention ~50 years' ago.

MIR light distinguishes diseased tissue, including cancer, by detecting the molecular-makeup of the tissue. Using MIR fibre-optics will enable a new type of endoscopy so that during cancer surgery the surgeon can guide MIR fibre laser light onto the tissue and collect the reflected light to molecularly map the tissue and instantly tell if all cancer is removed. Compact MIR fibreoptic systems will be enabled by using MIR broad- and narrow-band fibre lasers; for these, small-core MIR fibre is essential and this Project will enable the new extrusion technology to make this possible.

3. Biocompatible, therapeutic fibre

The human body does not reject biocompatible fibre. We will extrude new types of multi-layered and holey biocompatible glass preforms for bioimplant fibre of finely controlled dissolution rate in the body. This is for therapeutic drug and ion release from fibre at the site of body infection and for controlled dissolution fibre-biocomposites to implant in the body to support bone-healing.

4. Project synergy

This Project will encourage cross-fertilisation of ideas, for instance a bio-compatible glass cladding for MIR glass fibres may be beneficial and using biocompatible glass fibres for NIR (near-infrared) light transmission has the potential to allow in situ monitoring of tissue health in vivo.

1. IMPACT IN HEALTHCARE SECTOR

1.1 Biocompatible fibres- Project outcome

Therapeutic drug/ion delivery, in vivo, from dissolvable fibres is an outcome of this Project, benefiting: managing short-term trauma, chronic conditions, bone fracture, military injury; patient recovery times; patient quality of life during/after recovery; NHS costs and stimulation of new UK SME/large-scale industry products, as follows:

(i) managing chronic conditions of an aging UK population. Elderly people may suffer increasingly adverse health conditions with aging, requiring daily self-administration of drugs. Under-skin drug release, enabled by the slow dissolution of bioresorbable structured glass fibre to be made in this Project, removes patient stress to remember what drug? when? and enables more effective health-monitoring- the drug has been delivered. This aids better management of chronic conditions, lowering NHS costs and stimulating new UK SME/large-scale industry products.

(ii) in controlled-dissolution, biocomposites to support bone during bone fracture healing. Such short-term trauma can affect any UK citizen. Patient recovery times, patient quality of life during/after recovery, NHS costs, stimulation of new industrial products are beneficially impacted by the new bio-compatible biocomposites enabled in this Project.

(iii) biocompatible fibres for physiological monitoring of body healing processes through NIR (near-infrared) light transmission are an outcome of this Project. NIR monitoring of wound healing is a new field offering better recovery from trauma such as diabetic wound healing. Shrapnel/bullet wounds/other object-impact concern the military. Patient recovery times, patient quality of life during/after recovery, NHS/military costs and stimulation of new UK SME/large-scale industry products will benefit.

1.2 MIR fibres- Project outcome

MIR light tissue-interrogation gives greater molecular specificity than NIR light tissue-interrogation. This Project will help realise MIR fibres for portable, real-time, hyperspectral sensing/imaging in healthcare like real-time, in vivo early diagnosis, screening and intra-operative monitoring of cancer.

Skin cancer screening is done by the clinician in hospital. Whereas, in a primary care setting (GP surgery), a practice nurse trained to perform MIR light hyperspectral sensing/imaging of tissue could yield fast, objective information on if skin cancer is present. The impact is to filter out patients who must visit hospital. Patient stress, recovery times, patient quality of life during/after recovery, NHS costs, stimulation of new UK industrial products will be impacted by the new MIR fibres.

The 'Gold Standard' to identify cancer remains histopathology, that is: the visible-light microscopic study of the morphology of dye-stained, excised tissue to determine disease. Histopathology is labour-intensive and highly dependent on pathologist judgement. Patients must wait days/weeks for pathology results causing significant stress. For instance, awaiting pathology result of whether a tumour has been totally excised by surgery, where excised tumour margins are interrogated for cancer malignancy, necessitates interrupting surgery/perhaps 'sewing up'/further surgery. A rapid, on-the-spot MIR optical biopsy, using MIR fibreoptics allows a single procedure, saving NHS costs, avoiding wait, reducing patient stress.

3. IMPACT IN OTHER SECTORS

The MIR fibres to be made in this Project are a disruptive technology for molecular sensing/monitoring in: energy/environmental quality (e.g. exhaust gases for fuel efficiency/pollution); agriculture (e.g. ethylene gas in fruit ripening); manufacturing/chemical processing (e.g. distributed sensing oil fractionation); food/drink security, explosives'/narcotics' sensing for better public safety. Thus, MIR fibres benefit society and will catalyse new UK SME/large-scale industry products.