WO2013026999A1

WO2013026999A1 - A wound management system

Info

Publication number: WO2013026999A1
Application number: PCT/GB2012/000667
Authority: WO
Inventors: Iain Elder
Original assignee: Pulse Innovate Ltd
Priority date: 2011-08-19
Filing date: 2012-08-20
Publication date: 2013-02-28

Abstract

The present invention relates to a system, apparatus and method for management of wounds. In particular, but not necessarily restricted thereto, the present invention relates to a system for diagnosis and apparatus to assist in wound treatment which is particularly applicable to treatment of leg ulcers. The present invention also seeks to provide an intelligent dressing system that will lead to improved management of chronic wound care from both patient and economic perspectives. Dressing replacement in either a clinical or remote setting should be conducted dependent on the wound state as determined through evidence based diagnosis. A dressing system, according to the present invention, will enable the collection of wound state information through incorporated sensor technologies (temperature, pH, moisture and cell impedance) that respond to physical stimuli. Signals from these will be transmitted and can be monitored within a clinical environment or in a home setting, either by the patient or remotely by the health care professional using telecommunications technology. The dressing will also deliver regenerative therapy through appropriate application of electromagnetic stimulation in response to the wound state.

Description

A WOUND MANAGEMENT SYSTEM

Field of the Invention

The present invention relates to a system, apparatus and method for management of wounds. In particular, but not necessarily restricted thereto, the present invention relates to a system for diagnosis and apparatus to assist in wound treatment which is particularly applicable to treatment of leg ulcers.

Background to the Invention

The global market for wound care management products has been valued at $14bn (2009) and is forecast to reach $20bn by 2016. Within this global market, advanced wound management technologies -those used in the clinical management of wounds- represent a $5bn segment which is forecast to triple over the next 10 years.

A recent nationwide study in Germany on venous leg ulcers has revealed an average duration of wound of seven years resulting in some€8 billion being spent annually on chronic wound care with a large percentage spent on wound dressings. The other major cost associated with wound care is clinical time i .e. the costs of nursing, especially in the patients home with the cost of travel to and from patients an important element in that cost. In the UK the cost to the NHS has been estimated to be £400 million mainly borne by the community nursing services. Employment benefits associated with development and manufacture of the intelligent dressing. 2007 figures from the UK National Prescribing Centre revealed wound dressings costs of over £100 million excluding staff time. Current estimates put the total annual incidence of chronic wounds at almost 9 million worldwide and estimates range from 177 to 220 million cases of diabetes worldwide with up to 15% diabetic patients developing ulcers at some point. In any given year there are over 3 million diabetic foot ulcers. Within the EU, in Germany it is estimated that over 4 million patients suffer from venous, diabetic or pressure ulcers.

In humans - and mammals in general - injury triggers an organised complex cascade of cellular and biochemical events that seek to result in a healed wound. A preferred outcome is the restoration of anatomic continuity, capability and appearance.

A simple, uncontaminated, wound at the skin surface of a human subject heals by a process which can be divided into several stages and sub-stages. Following an injury, healing processes are automatically instigated and may continue for years after closure of the wound surface. The typical stages of wound healing are approximately as follows; I. Inflammation (immediate to 2-5 days), when various effects are triggered, such as: Haemostasis, Coagulation, Vasoconstriction, Vasodilation, Platelet aggregation, Phagocytosis and Control of pathogenic organisms; II. Proliferative Phase (2 days to around 3 weeks), when further events occur such as granulation of tissue, where fibroblasts lay a bed of collagen, contraction, where wound edges pull together to reduce defect, epithelialisation, when new epithelial surfaces are formed especially across moist surfaces of a wound; III. Remodelling Phase (around 3 weeks to 2 years), when collagen is produced to increase the tensile strength of wounds and scar tissue is formed.

Macrophages and fibroblasts of the body perform many of the tasks involved in tissue regeneration; infection of wounds by bacteria delays the healing process, since bacteria compete for nutrients and oxygen with such macrophages and fibroblasts. Infection results when invading organisms (typically bacteria) achieve a level of dominance over systemic and local factors at a wound site - a septic response may arise - the multiple processes involved in wound healing are inhibited and delayed. Infection can result in a prolonged inflammatory phase and may cause further necrosis of the wound, expanding the wound site and delaying healing still further. The granulation phase of the healing process will begin only after the infection has subsided and thus the dominance of the invading organism has been overcome.

Chronic wounds almost without exception contain bacterial flora. These bacteria may be indigenous to the patient or might be exogenous to the wound. Closure of a wound is effectively possible by control of the level of this bacterial flora. Just because there is bacteria and foreign matter present within a wound, does not give rise to an infection; no negative impact may be realised. Accordingly wound control is not determined by control of the presence of bacteria, other organisms and foreign bodies at a wound site. The provision of wound information enables a tailored response by a physician whereby to enable wound repair to be facilitated; any treatment can be treated topically as opposed to having to use systemic antibiotics. This would also lead to less clinical intervention/hospitalisation (e.g. due to sepsis) and would reduce the use of antibiotics and other complications of infection.

Current methods used to identify bacterial infection rely mainly upon subjective judgement of the odour and appearance of a wound. With experience, it is possible to identify an infection in a wound by certain signs, such as redness or pain, particularly once the infection is well established. Intervention by way of the taking of swabs followed by laboratory analysis to identify specific organisms takes time and may simply indicate that bacteria are present rather than indicating that the equilibrium is shifted in favour of the pathogen. As a result, swabs are primarily of value to identify the invading organism once it is apparent from other signs that infection exists.

There are many companies and public bodies seeking to develop intelligent dressings for chronic wounds, especially chronic leg ulcers and "hard to heal" wounds and other type of wounds, such as post-operative burns.

The review and control of chronic health conditions in a large population is difficult and wound care practice in either clinical or home settings is based on inspection and dressing replacement for which the timing is both variable and highly empirical. For chronic wounds, there is currently no alternative to a direct intervention by a healthcare professional in the home or the practice setting and wounds which progress or fail to heal are currently referred to specialist centres or tertiary surgical services. Any delay until the onset of significant health problems, complications, and declining health is simply too late, poor for patient care and expensive.

Substantial effort has been focused on development of sensors based on biomarker detection in a wound has been explored, encountering the challenges of selectivity, sensitivity and stability. The linkage between physiological parameters temperature, pH, moisture and cell impedance, measured independently, and wound state has been explored confirming the utility of these measures as indicators of wound health. This work, conducted at a fundamental level recognises that focused measure at a single point is restrictive and does not represent the overall wound state. Certain development agencies favour exploring the complexities of wound healing for blunt trauma, burn, and open wounds. While much of this work is focused on the urgent and immediate needs for military purposes, with focus on haemorrhaging and burn treatments, the long-term benefits of this work will be widespread. Yet another problem is that of open wounds, such as those affecting people with diabetes, that do not close to allow tissue regeneration to begin.

Modern dressings usually use synthetic polymers and range in complexity depending on application. Ordinary dressings are passive constructs such as gauze that simply cover the wound. Interactive materials contain polymeric films and foams which have properties suitable for shallow wounds with low exudates, permitting wound checking. Finally bioactive wound dressings are produced using materials such as hydrocolloids, alginates and collagens with state of the art dressings incorporating active ingredients such as antimicrobials and growth factors. It is known that the maintenance of a moist wound environment promotes the healing of wounds, especially burns and chronic wounds such as ulcers. However, it is also desirable to avoid excessive moisture or pooling of wound exudate on the wound, since liquid exudate causes maceration of skin adjacent to . the wound and other difficulties. Furthermore, liquid exudate can leak from the wound site and contaminate clothes or bedding.

In practice, it is difficult to maintain the desired moisture level at the wound site because the rate of wound fluid production varies from wound to wound, and over time for any single wound. This can necessitate frequent dressing changes and a range of dressing types to treat different wounds. For example, infected wounds generally produce substantially more exudate than non-infected wounds. Surgical wounds have an acute inflammatory phase of a few days during which discharge is significant, after which the rate of exudate production can be expected to fall sharply.

EP-A-0123465 describes the use in surgical dressings of continuous polymer films formed from materials that have raised moisture vapour permeability levels when the film is wet than when the film is dry. EP-A-0875222 describes wound dressings comprising a non-swelling, water impermeable apertured sheet having slits cut therein, wherein the apertured sheet is laminated to a water swellable foam layer. Absorption of wound fluid causes the foam layer to swell, and the resulting deformation opens the slits in the apertured sheet thereby increasing the liquid permeability of the apertured sheet.

EP0599589 provides wound dressings comprising a molecular filtration membrane having a maximum pore size in the range of from 0.001 pm to 0.5 m, and preferably in the range of from 0.01 pm to 0.25pm. The wound dressings may also comprise an absorbent layer atop the molecular filtration membrane and/or a wound contact layer of wound-friendly bio- absorbable material for contacting the wound.

EP-A-0122085 describes wound dressings having an apertured sheet of water swellable material laminated to a less water-swellable layer. Slits are cut in the apertured sheet. In use, differential swelling of the apertured sheet and the underlying layer causes the slits in the apertured sheet to open, thereby increasing the permeability of the apertured sheet to wound fluid.

US2011015591 provides a negative pressure therapy device for diabetic ulcers and a method of use to evaluate and monitor healing progress of wound and/or to generate data to modify or identify a treatment protocol . Fluid exudate removed from the wound by a negative pressure therapy device is analyzed to review progress of wound healing, such as whether healing is progressing in a positive manner or experiencing one or more impediments. In addition, one may separately utilize optical sensors integrated into a dressing enclosure. Such optical sensors may then illuminate the wound and collect information regarding the wound via a light scattering type response. Specifically, an optical sensor in the dressing enclosure, configured to provide varying wavelengths of light to said wound location to monitor selected wound healing events, including fibrosis, or wound biological conditions and/or delivery of drugs, etc.. WO2004086043 provides a method of predicting or diagnosing clinical infection of a wound comprising measuring the concentration of a marker associated with an inflammatory response in wound fluid. Also provided is a use of a wound dressing or biosensor comprising components of an assay system for measuring the concentration of a marker associated with an inflammatory response, for diagnosing clinical infection of a wound. WO 2009122188 provides a method for indicating the infection-status of a wound by measuring the concentration of calprotectin and provides devices suitable for performance of such monitoring. Such devices take the form of, for example, test strips, swabs, sheets or wound dressings.

US 2006111657 provides a wound treatment device comprising a water- impermeable envelope having at least one aperture, wherein the envelope contains a therapeutic substance, and the aperture in the envelope is blocked by a material that breaks down in the presence of one or more active components of wound fluid thereby permitting the therapeutic substance to contact the wound fluid. GB2408330 provides a wound dressing wherein the pH of a wound may be assessed using a film preferably of hydrogel which changes colour in dependence upon pH. Wound pH information may be used to facilitate selection of the appropriate treatment to which the wound should be subjected. Suitably, the hydrogel film is incorporated into a dressing.

Object to the Invention

The present invention seeks to provide an improved wound dressing. The present invention seeks to provide an improved wound dressing which overcomes at least some of the problems that have become apparent with regard to known systems.

The present invention also seeks to provide an intelligent dressing system that will lead to improved management of chronic wound care from both patient and economic perspectives. Dressing replacement in either a clinical or remote setting should be conducted dependent on the wound state as determined through evidence based diagnosis. The present invention seeks to provide an improved structure for wound treatment which not only provides a complete barrier to bacteria and other external contaminants but also optimizes the wicking and amount of wound fluid which can be retained in the volume provided by the absorbent fabric, thereby minimizing the frequency of dressing changes required in the wound treatment procedure.

The present invention seeks to provide an improved wound dressing which seeks to provide feedback data relating to healing progress of the wound.

Summary of the Invention

In accordance with a first aspect of the invention, there is provided a wound management system, incorporating one or more sensors relating to measurement of a physiological condition, the system comprising a sensor array printed on a flexible substrate to monitor the healing process by means of measurement of at least two or more parameters such as temperature, moisture, impedance, Ph, levels of particular compounds or gases, light absorption or light transmission, the sensors being arranged in at least a two dimensional triangulation arrangement whereby to assist in clinical decisions. The present invention accordingly enables control of a wound infection to be more simply managed by the review of certain key indicators associated with wound exudate components that are present at a wound site.

The sensors can be specific in their function, for example, the gas sensor can be operable to determine levels of nitric oxide, and the sensors may comprise devices attached to the printed flexible substrate. The light sensor may comprise an emitter and receiver operating at specific wavelengths. For example an exudate blanking out a particular wavelength may readily ascertain a particular condition. Conveniently, the sensors are arranged in a three dimensional triangulation arrangement, whereby specific determination of a condition is further assisted.

Conveniently, the wound' management system further comprises an electromagnetic coil, the coil being operable to create a pulsed electromagnetic wave to promote the healing process. The coil could also assist in the release of ions in solution from a pad or reservoir within the dressing.

Preferably, the sensors are arranged to provide an informatics capability relative to wound progress, the informatics capability enabling data to be transmitted, to a remote device. The sensors could provide data to processor circuitry which can process the data for storage or transmission or for storage and subsequent transmission via wi-fi data transfer protocols. By the collection and collation of informatics data, a history / library of wound conditions using different demographics e.g. gender, age, condition and dressing type can be generated. This will in turn have a major influence ensuring that the right treatment is given at an early stage to prevent the misuse of drugs, thereby playing a major role in reducing the drugs bill. Other major cost saving will be accrued in saving nursing time, as they will be able to prioritise home visits, and make major savings on travelling costs, both which take up the majority of costs for district and community nursing. It will also have an impact in reducing our carbon footprint.

The system can incorporate an alarm, whereby to alert a health care professional or user of the wound management system that a condition has been reached in respect of one or more sensor readings. The information can be sent via a mobile phone, via a "mobile application", an SMS alarm system or a patient diagnostic assembly, whereby to enable remote calls for help/support/attendance to be addressed.

The wound management system could include a sensor array printed on a flexible substrate such as a flexible printed circuit to enable at least some of the functionality of the dressing, by way of provision of transmission path, capacitance or impedance. A micro sensor camera array may be present, whereby to enable images to be transferred from the wound. Nano-fibres, provided with a conductive coating may be used in the construction of the dressing system to enable an electric current to be passed about the wound.

In some circumstances, it can be preferable that the dressing comprises a dressing layer which can be seen though a transparent outer layer, the dressing layer being adapted to change colour in the presence of one or more pathogens/ upon a level of hydration / presence of a specific compound / upon a level of hydration of conductivity. Indeed, the dressing can comprise a dressing layer which can be seen though a transparent outer layer, the dressing layer being adapted to change colour in correspondence with a particular temperature range.

The wound management system can comprise a rechargeable electrical cell or battery. Conveniently the rechargeable electrical cell or battery is a one of a cadmium-nickel, lithium-ion or lithium-polymer cell or battery. Even more preferably the electrical cell or battery is plastically deformable.

By the provision of feedback data relating to the progress of the wound, the wound management system can be left in situ upon a patient (preferred, lest a wound be further damaged upon inspection), a course of treatment can be modified or a new course of treatment considered. W

A dressing system, according to the present invention, will enable the collection of wound state information through incorporated sensor technologies (temperature, pH, moisture and cell impedance) that respond to physical stimuli. Signals from these will be transmitted and can be monitored within a clinical environment or in a home setting, either by the patient or remotely by the health care professional utilising mobile technology data transfer and for provision of instructions and/or prescriptions. The dressing can also deliver regenerative therapy through appropriate application of electromagnetic stimulation in response to the wound state. Remote prescription of treatment and or medication is also possible.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which :

Figure 1 is an exploded view of a basic wound treatment system in accordance with the present invention;

Figure 2 is a schematic diagram of a printed electromagnetic element suitable for use in the system of Figure 1 ;

Figure 3 shows a basic galvanic cell concept;

Figures 4 & 4a shows an arrangement of components upon two layers of a wound system as shown in Figure 1;

Figure 5 shows how a wound dressing in accordance with the invention can communicate with a home hub; and

Figure 6 shows how a wound dressing in accordance with the invention can communicate in a healthcare system.

Detailed Description of the Preferred Embodiments

There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific.

Figure 1 is an exploded view of a wound treatment system according to an embodiment of the present invention. The system includes a wound containment and exudate absorbing layer (A), an encapsulation layer (B), a sensor support layer (C), an encapsulation/strike through barrier (D) and an electromagnetic element support layer (E). The electromagnetic element as illustrated in Figure 2, preferably comprises a planar spiral copper coil on a polymeric substrate and a high- permeability magnetic layer (equivalent to the core of a conventional electromagnet) in the form of a ceramic/polymer composite; an electrical cell, such as a lithium ion-ion electrical cell (often referred to as a battery) can be placed between the encapsulation barrier and encapsulation layer. The copper spiral may be fabricated by Focussed Field Deposition (FFD) onto a flexible polyamide substrate. However other candidate methods of manufacture are also possible.

The ceramic/polymer composite is deposited on both sides of the substrate by stencil and screen printing, above and below the copper spiral coil, with respect to layer E. FFD technology, which is a non-immersion additive electroplating process, was primarily designed to produce flexible circuitry using electro deposited copper extracted from copper sulphate solutions. Because copper is deposited on the substrate only where necessary and only in the amount needed, the process will significantly lower production costs compared with prior similar technologies. The advantages of using FFD for the copper spiral coil are that it: - is a non-immersion process - allows multiple substrate choice - uses independent circuit patterns with no connections or robber bars means no waste - has a totally controlled thicknesses capability across thickness profile. To obtain sufficient permeability and volume magnetization for the required degree of enhancement of the magnetic field, the mass fraction of the ceramic in the ceramic/polymer composite must be greater than the mass fractions of fillers typically incorporated into polymer-matrix thick films. In general, such a high mass fraction of filler can adversely affect adhesion and can make the film susceptible to mechanical failure and delamination during flexure. These adverse effects can be overcome by an appropriate choice of polymer resin and the ceramic magnetic powder filler for the film formulation, in conjunction with the use of a hermetic-coating technique. The wound dressing system will require power to enable data gathering, transmission and electromagnetic stimulation to enhance wound healing rate. Conveniently, flexible lithium ion batteries such as the flexible lithium polymer electrical cells as produced by Solicore, Inc., marketed under their "Flexion" trade name. Such lithium cells are available in a variety of shapes and sizes. 3V at 10mA can be provided in a package dimensioned at less than 26 x 29 x 0.45mm.

The lithium-ion cell can be recharged, conveniently by means of an inductive charging system associated with the protective barrier layer. Inductive charging uses the electromagnetic field to transfer energy between two objects. A charging station transfers electrical energy through inductive coupling to an electrical device, which stores the energy in the lithium-ion cell or similar. As is known, the flow of electrical charge associated with the charging apparatus induces an electrical field with the coupling element embedded in the protective barrier layer causes, which induced field can be employed to re-charge a lithium-ion rechargeable cell or similar. Inductive charging carries a far lower risk of electrical shock, when compared with conductive charging, because there are no exposed conductors. The ability to fully enclose the charging connection also makes the approach attractive where water impermeability is required; for instance, inductive charging is used for implanted medical devices that require periodic or even constant external power, and for electric hygiene devices, such as toothbrushes and shavers, that are frequently used near or even in water. Inductive charging makes charging mobile devices more convenient; rather than having to connect a power cable, the unit can be placed on or close to an inductive charge adaptor. The main disadvantages of inductive charging are its lower efficiency and increased resistive heating in comparison to direct contact. Implementations using lower frequencies or older drive technologies charge more slowly and generate heat for most portable electronics. Inductive charging also requires drive electronics and coils that increase manufacturing complexity and cost.

In an alternative, a recharging mechanism can be created in combination with the exudates. Since an exudate is an electrolyte, a galvanic cell can be created, by the use of metal terminals in contact with exudate. Suitable metals have been determined to be copper and zinc; a 1.1V potential difference can be obtained across a sulphate salt bridge, the zinc becomes oxidized and passes into solution and the copper-ion solution is reduced. Zinc metal becomes oxidised to zinc oxide and the copper is reduced. A simple overview of a zinc-copper electrochemical cell is shown in Figure 3. Accordingly, using printed/sputter coated technologies, for example, an electrical cell can be produced which is activated when placed in- exudate; water present in the exudate can react with the salt bridge to provide circuit continuity between a zinc anode and a copper cathode, which are connected to electrical circuits, in particular to enable a rechargeable battery to be recharged.

With regard to possible contraindications with the body, it is to be noted that zinc oxide is often used in topical applications; whilst zinc oxide can be photoreactive, meaning that when it is exposed to UV light it can generate reactive oxygen species, or free radicals, when enclosed by protective plasters, this has not been found to be an issue. With regard to the presence of copper, it is well known that trace amounts of copper are important for the human body in general and copper is one of a relatively small group of metallic elements which are essential to human health. Indeed, copper plays an important role in collagen formation, a connective tissue in the skin, and helps in the formation of cross-links in collagen and elastin and thereby maintain and repair connective tissue. Indeed, copper has been used as a medicine for thousands of years including the treatment of chest wounds and the purifying of drinking water. More recently, research has indicated that copper helps prevent inflammation in arthritis and similar diseases. The capacity for healthy human livers to excrete copper is considerable and it is primarily for this reason that no cases of chronic copper poisoning have been reported.

Referring again to the ceramic/polymer composite, electrical components can be deposited on both sides of the substrate by stencil and screen printing, above and below the copper spiral coil. FFD technology, which is a non-immersion additive electroplating process, was primarily designed to produce flexible circuitry using electro deposited copper extracted from copper sulphate solutions. Because copper is deposited on the substrate only where necessary and only in the amount needed, the process will significantly lower production costs compared with prior similar technologies. The advantages of using FFD for the copper spiral coil are that it: - is a non-immersion process - allows multiple substrate choice - uses independent circuit patterns with no connections or robber bars means no waste - has a totally controlled thicknesses capability across thickness profile. To obtain sufficient permeability and volume magnetization for the required degree of enhancement of the magnetic field, the mass fraction of the ceramic in the ceramic/polymer composite must be greater than the mass fractions of fillers typically incorporated into polymer-matrix thick films. In general, such a high mass fraction of filler can adversely affect adhesion and can make the film susceptible to mechanical failure and delamination during flexure. These adverse effects can be overcome by an appropriate choice of polymer resin and the ceramic magnetic powder filler for the film formulation, in conjunction with the use of a hermetic-coating technique.

Returning to the fabrication of low cost sensor arrays, not only will volume manufacturing by printing technologies reduce cost, but new applications can be adapted. As is discussed above, the cells for the delivery of electromagnetic fields can be developed. Similarly, other types of sensors can be readily fabricated. For example by the use of temperature dependent resistor, temperature determining array structures can be determined, not only generally, but also to particular areas of a wound; local temperature variation can be useful in determination of progress of wound management.

Plastic semiconductors are based on pi-conjugated molecular electronic materials (MEMs) that are capable of absorbing and emitting light and conducting charge, just like inorganic semiconductors. They have the advantages that the properties, such as emission wavelength, can be tuned through chemical design, that the materials are tough and flexible, and that they can be processed from solution so that devices can be manufactured by relatively simple and low-cost printing or coating methods. Structures with a large number of embedded sensors are becoming more common, and this refined spatial information can be used to advantage in damage location and model validation.

The applications of plastic electronics include displays, energy efficient lighting, sensors, flexible electronic circuitry, sensor arrays, solar cells, and applications in medical imaging, bio-electronics, memory devices, and more. For example semiconductor lighting application can be employed on a pulsed basis to provide low consumption light sources for the use in transmission and absorption characteristics of exudates, whereby to provide further characterisations of the wound. Such sensors can be provided upon layer C which not only provides encapsulation properties, but can also support further sensors.

Layer A is in contact with the wound and conveniently comprises nano-fibre technology operable to allow the dressing to absorb and hold exudates from an infected wound; the increase in area of non-fibres appears to provide improved absorptive properties; the nano-fibres may also retain medicaments, for example, specific antibiotic preparations and the like,

Layer B is shown as an optional indicative membrane layer, which can comprise a generally transparent layer; non-opaque colourations can be indicative of a healing wound; certain exudates may provide distinct indications to a health care professional. The indicative membrane may be treated to become a particular colour in the presence of particular exudate matter. This can provide an early warning of a rapid wound regression as well as assisting in a patient to become more actively involved in their wound management.

Layer C, as well as being an encapsulation layer can also act to support sensors, in which case, electrical connections as present between layers El and D may also be required. A sensor array fixed into layer C could assist in the monitoring of wound progression or regression through the measurement of cell impedance, pH value and Nitric Oxide levels. It will be appreciated that sensors relating to specific conditions may benefit from being supported on a particular layer; indeed it is necessary for certain indications to be measured within the exudate, for example. The particular order of layers may change; specific layers may not be required, such as the indicative membrane layer and the particular layers will be dependent upon the need of a wound to be dressed, as will be readily appreciated by healthcare professionals.

In the printing process to fabricate sensor arrays for physiological measurement, inkjet and contact printing processes (e.g. flexography) may be used to deposit functional materials for which ink properties and process need to be matched. Non contact methods are capable of high resolution ( lOpm) but for functional materials speeds up to ~ 1.0m/min are typical to achieve the deposit thickness over large areas. Flexography is capable of printing 50pm features and because of the image manufacturing process it is unique in that this can be achieved for any feature geometry and with printing speeds of up to 60m/min.

It will also be appreciated that the printed circuits, controlled by suitable computer circuit chips under software control shall be able to perform testing of the electrical characteristics of the exudate, for example the impedance; if treating is performed on a regular basis, changes can be monitored, which can be aligned to conditions of the wound itself; alarm statuses can be determined so as to indicate when inspection of the would by a medical profession is indeed warranted. Similar test systems can be developed for temperature measurement, which can simply comprise resistive temperature sensors or could comprise a thermocouple arrangement.

The delivery will require the patterning of sensor arrays to gather information at discrete points over the wound area. This will be developed through printing technology and acquisition of data from these will be achieved through a wireless communication. Data processing and display will be required to provide a tool to diagnose wound state and this will include progression through capture of longitudinal data. Remote monitoring will require data transmission through appropriate telecommunications, with emphasis on security and patient sensitive information. Healing enhancement will be delivered through electromagnetic stimulation. Power will be required to achieve this and the aim will be to deliver this through power scavenging or rechargeable battery technology.

Through testing and trials within a clinical setting, it is believed that algorithms can be developed to perform wound state diagnosis based on single or multi sensor inputs. Cost modelling and life cycle analysis will be used to guide design and manufacturing options, including designs that cover recycling and disposal options for the active elements.

As with many testing equipment, digital cameras are becoming extremely small; indeed certain cameras such as CMOS micro cameras are becoming known as disposable as such. Dimensions of such cameras can be as small as 2 x 2 x 5 mm; with a weight of less than 0.5g such cameras can be simply incorporated within a wound dressing. Applicants have developed the use of such cameras and broad band lighting, for example using semiconductor light sources to determine visual observations of a wound site; by the use of mushroom lenses, a relatively broad view can seen, which can provide a simple non-invasive indication of wound status. As will be appreciated, colour sensors can be provided with filters suitable for the monitoring of particular conditions. Such camera systems can be utilised with many standard transmission systems, such as PAL and NTSC video systems. Upon transfer of data, it will be realised that a clinician can enable comparison . of pictures whereby to perform reviews of wound healing progress.

Such cameras include a Charge Coupled Device (CCD) to take images and can be connected to a wireless data transfer unit, operable to transfer the data employing a buffer assembly and memory whereby to transfer the, visual data to a health care professional. An RGB filter system can be provided to generate high quality images. In video mode, a typical CCD camera can take 30 frames of image per second.

Measurement relating to pH can be performed using standard measurement circuitry; a pH probe will measure pH as the activity of hydrogen cations surrounding a thin walled glass bulb, the probe producing a small voltage that is displayed as pH units by the meter, the meter circuit comprising nothing more complicated than a voltmeter with a very high input impedance (approximately 20- 1000ΜΩ).

Solid capacitive polymer structures can be employed to determine the relative humidity and temperature in wound applications; due to the nature of such characteristics, a single sensor wound system may well be appropriate and is directly connected to a control and data transfer module.

In mammals, nitric oxide NO is an important cellular messenger molecule involved in many physiological and pathological processes. Low levels of NO production are important in protecting an organ such as the liver from ischemic damage. Chronic expression of NO is associated with various carcinomas and inflammatory conditions including juvenile diabetes, W multiple sclerosis, arthritis and ulcerative colitis. Levels of NO can be tested using various indicators.

With reference to Figure 4a shows the inside surface of the outer protective layer D, which is provided with a coil and separate hard wires 49. Figure 4b shows the ceramic/polymer layer E, together with can provide real estate for the mounting of components such as wi-fi / GPRS / radio telecom antennas 42; surface tracks 44 for inductive charging of rechargeable electrical cells 46; control chip 47 mounting and memory 48 mounting and control circuitry. Conductive tracks between layers can be formed by deposition and cold soldering techniques as well as by separate wires 49. Further, interlocking tracks between first and second adjacent layers could also be possible, in addition to other methods of establishing continuous electrical contact as will be known to those skilled in the art.

Referring now to Figure 5, there is shown a limb 50 of a patient with a dressing 51 in accordance with the present invention. Data transmission by RFID technology is now established; many protocols are employed for wi-fi, home automation etc.. Nonetheless, in terms of data transfer regarding urgent and non-urgent data transfer, certain protocols may be required to be developed, bearing in mind that it is becoming established that control of an infection can be more simply managed by the review of certain key indicators associated with a wound site. The dressing transmits signals to a home hub base station 52. The home hub can then transmit signals to mobile device 53or a laptop 55 of the patient, a health care professional, patient family member etc. using similar wif-fi home automation channels or, indeed, general wireless telephony channels. Conveniently, the wound dressing system may transmit data, for example for the past 24 hours with the use of the memory associated with the control electronics. The wound dressing could be provided close to the home hub; there may in the alternative be an inductive data transfer method. The data transfer may be enabled at specific times or may be determined from time to time and only when the wound system is in data transfer proximity to the home hub. The home hub may communicate via mobile telephony channels, cable, satellite and other transmission channels.

However, with reference to Figure 5, the home hub has a dressing adaptor 56 that corresponds to the wound system so that it can be placed over the dressing, so that inductive charging can take place. The system may also be adapted so that charging is provided by way of a usb connection to a home pc; no specific home hub need be provide. For example a software download may the only requirement, whereby the systems can be adopted in a widespread health care scenario with no significant expenditure - assuming that a patient has a home pc or laptop computer; rather than wireless data transfer communications, secure e-mail communications could be deployed.

Referring now to Figure 6, there is shown an overview of healthcare professionals' management of a wound infection in accordance with the present invention. The home hub 52 communicates with a hospital, a clinic the patient's GP practice and his assigned district nursing team. Videos and still pictures can be transferred; data relating to other indications regarding status of pH, temperature profile, light colour transmission data determination nitric oxide and wound oxygenation (important in diabetic condition review) and other relevant data.

The present invention takes advantage from the fact that control of a wound infection can be more simply managed by the review of certain key indicators associated with wound exudate components that are present at a wound site.

Claims

1. A wound management system, incorporating one or more sensors relating to measurement of a physiological condition, the system comprising a sensor array printed on a flexible substrate to monitor the healing process by means of measurement of at least two or more parameters such as temperature, moisture, impedance, Ph, concentration of particular compounds or gases, light absorption or light transmission, colour, salinity, the sensors being arranged in at least a two dimension triangulation arrangement whereby to assist in clinical decisions.

2. A wound management system, according to claim 1, wherein the optical sensors comprise one of a light emitter and an optical receiver, arranged for transmission and/or reflectance measurements for one or more wavelengths.

3. A wound management system, according to claim 1 or 2, wherein the sensors are arranged in a three dimension triangulation arrangement.

4. A wound management system, according to claim 1 to 3, wherein the system further comprises an electromagnetic coil, the coil being operable to create a pulsed electro-magnetic wave to promote the healing process.

5. A wound management system, according to claim 4, wherein the electro-magnetic wave operates to assist in a release of ions in solution from a pad or reservoir within the dressing.

6. A wound management system, according to claim 1 to 5, wherein the sensors are arranged to provide an informatics capability relative to wound progress, the informatics capability enabling data to be transmitted to a remote device.

7. A wound management system according to any one or more of claims 1 - 6, wherein the sensors provide data to processor circuitry which can process the data for storage or transmission or for storage and subsequent transmission via wi-fi data transfer protocols.

8. A wound management system according to any one of claims 1 - 7, wherein the system incorporates an alarm, operable to alert a health care professional or user of the wound management system that a condition has been reached in respect of one or more sensor readings.

9. A wound management system according to any one of claims 1 - 8, wherein information from the sensors is sent via a mobile phone, via a "mobile application", an SMS alarm system or a patient diagnostic assembly, whereby to enable remote calls for help/support/attendance to be addressed.

10. A wound management system according to Claim 9, wherein the information communicated comprises at least some of gender, age, condition and dressing type.

11. A wound management system according to any one of claims 1 - 10, wherein the system comprises a rechargeable electrical cell or battery.

12. A wound management system according to claim 11, wherein the rechargeable electrical cell or battery is a one of a cadmium-nickel, lithium- ion or lithium-polymer cell or battery.

13. A wound management system according to claim 11 or 12, wherein the electrical cell or battery is a plastically deformable.

14. A wound management system according to any one of claims 1 - 10, wherein, a supplemental electric power sources can be provided by metals in a galvanic series in combination with the exudates acting as an electrolyte.

15. A wound management system according to any one of claims 11 - 13, wherein, the electrical cells or battery can be recharged by an electric power source provided by metals in a galvanic series in combination with the exudates acting as an electrolyte.

16. A wound management system according to claim 14 or 15, wherein copper and zinc are placed within the exudate, as electrical terminals in contact with exudate as the metals of the galvanic series.

17. A wound management system according to claim 14 or 15, wherein printed/sputter coated technologies, are employed to define the metals of the electric power source.

18. A wound management system according to Claims 1 - 17, wherein the sensor array printed on a flexible substrate comprises a flexible printed circuit to enable at least some of the functionality of the dressing, by way of provision of transmission path, capacitance or impedance.

19. A wound management system according to Claims 1 - 18, further comprising a micro sensor camera array whereby to enable images to be transferred from the wound.

20. A wound management system according to Claims 1 - 19, wherein nano-fibres, provided with a conductive coating enable an electric current to be passed about the wound.

21. A wound management system according to Claims 1 - 20, wherein the dressing comprises a dressing layer which can be seen though a transparent outer layer, the dressing layer being adapted to change colour in the presence of one or more pathogens/ upon a level of hydration / presence of a specific compound / upon a level of hydration of conductivity.

22. A wound management system according to Claims 1 - 21, wherein the dressing comprises a dressing layer which can be seen though a transparent outer layer, the dressing layer being adapted to change colour in correspondence with a particular temperature range.

23. The use of a wound management system according to any one or more of claims 1 - 22, to monitor the condition of a person with a wound.

24. The use of a wound management system according to any one or more of claims 1 - 22, to enable remote diagnosis of a condition of a person with a wound.

25. The use of a wound management system according to any one or more of claims 1 - 22, to enable prescription of medicine and /or treatment in the treatment of a person with a wound.