Laser-induced graphene deposit and method of forming the same

Abstract

There is described a method for forming a laser-induced graphene deposit in a dressing material, wherein the graphene deposit is suitable for use as an electrode, the method comprising: providing a dressing material; applying an absorber to the dressing material; irradiating the absorber with a laser such that a temperature of a portion of the dressing material proximate the absorber is increased thereby forming a graphene deposit in the portion of the dressing material. Further, there is described a laser-induced graphene electrode obtainable by the method, and a dressing material comprising the laser-induced graphene electrode. A device for detecting moisture and a skin barrier for an ostomy appliance comprising the device are also described.

Description

[0001] LASER-INDUCED GRAPHENE DEPOSIT AND METHOD OF FORMING THE SAME

[0002] The present application relates to laser-induced graphene deposits, particularly laser- induced graphene deposits in a dressing material which allow detection of moisture.

[0003] Background

[0004] Colorectal conditions such as inflammatory bowel disease, trauma, diverticular disease, and malignancy can require surgical intervention and intestinal diversion through the creation of a stoma. A stoma is a surgical opening on the abdomen through which bowel contents are directed into an external pouch. There are between 175,000 and 205,000 individuals who have undergone an ostomy (ileostomy, colostomy and urostomy) in the UK, with over 20,000 new stomas created each year.

[0005] Dehydration and electrolyte disorders can arise in individuals recovering from ostomy surgery as they adapt to the changes to their digestive system, in particular persistent loss of bowel fluid. Further, individuals may suffer peristomal skin complications and moisture associated skin damage around their stoma through prolonged exposure to fluid. The moisture of peristomal skin may also affect the adhesion of an ostomy appliance to the skin leading to leakage which can cause anxiety for those new to stoma management and attempting to re-engage with social activities and return to employment.

[0006] Summary of the Invention

[0007] According to an aspect of the invention, there is provided a method for forming a laser- induced graphene deposit in a dressing material, wherein the graphene deposit is suitable for use as an electrode, the method comprising: providing a dressing material; applying an absorber to the dressing material; irradiating the absorber with a laser such that a temperature of a portion of the dressing material proximate the absorber is increased thereby forming a graphene deposit in the portion of the dressing material.

[0008] The absorber is applied to the dressing material to interact with the laser during irradiation to result in the photothermal conversion of the portion of the dressing material into a carbonised deposit, suitable for use as an electrode. Each graphene deposit may be used as an electrode in, for example, a two-probe conductivity cell configured to detect hydration and / or swelling of the dressing material.

[0009] The method may involve generating a laser beam to produce the graphene. The method may involve using a laser diode to generate the laser beam. The method may involve suing a laser power of between 50 and 100%. The laser power may be 60% or 80%. Further, the laser power may be between 2 and 10 W, or between 2 and 8 W. Optionally, the laser power may be 5 W.

[0010] The method may involve using a laser wavelength between 300 and 600 nm, between 400 and 500 nm, or between 440 and 460 nm. Optionally, the laser wavelength is 455 nm.

[0011] The method may involve using a raster speed between 1000 and 3000 mm / m inute, or between 1500 and 2500 mm / minute. Optionally, the raster speed may be 200 mm / minute.

[0012] The method may further involve using a line scan density of between 1 and 8 lines / mm, or between 2 and 7 lines / mm. Optionally, the line scan density is 3 lines / mm.

[0013] In some embodiments, applying an absorber to the dressing material comprises applying an ink to a surface of the dressing material. In some embodiments, applying an absorber to the dressing material comprises adhering a film to a surface of the dressing material. In some embodiments, the absorber is dark pigmented. The dark pigmentation of the absorber may improve an efficiency of photothermal conversion of the dressing material to a graphitic deposit.

[0014] The method may involve passing the laser beam over the dressing material at least once, at least twice, or at least three times. Optionally, the method involves three passes of the laser beam over the dressing material. The method may involve defocusing the laser beam at a target area of the dressing material. The target area is the area where the graphene is formed. The defocusing may be performed by moving the dressing material away from the laser diode.

[0015] In some embodiments, the dressing material comprises hydrocolloid material. In other embodiments, the dressing material may comprise polyimide. In other embodiments, the dressing material may comprise any suitable cellulosic material.

[0016] In some embodiments, the method further comprises removing the absorber from the dressing material. In some embodiments, removing the absorber from the dressing material comprises dissolving the absorber using a solvent. In other embodiments, particularly where the absorber is a film, removing the absorber may comprise peeling the film away from the dressing material.

[0017] In some embodiments, the method further comprises irradiating the graphene deposit with a laser to increase an extent of the graphene deposit in the dressing material. In this way, once the initial photothermal conversion of the dressing material to graphene has begun, a size of the graphene deposit may be increased by irradiating the graphene deposit itself with a laser.

[0018] In some embodiments, when a temperature of the portion of the dressing material is increased, sp3 carbon in the dressing material is converted to sp2 carbon thereby forming a graphene deposit in the portion of the dressing material. The dressing material may comprise sp3 carbon. Sp2 carbon may be common to graphene materials. During irradiation, the sp3 carbon present in the dressing material is converted to sp2 carbon. When the latter predominates, a graphene deposit may be formed in the dressing material.

[0019] According to another aspect of the invention, there is provided a laser-induced graphene electrode in a dressing material obtainable by the method of the invention.

[0020] According to another aspect of the invention, there is provided a dressing material comprising a laser-induced graphene electrode, wherein the dressing material comprises hydrocolloid material. In some embodiments, the electrode is embedded within the dressing material.

[0021] According to another aspect of the invention, there is provided a device for detecting moisture comprising: a dressing material comprising a plurality of laser-induced graphene electrodes; wherein the dressing material comprises hydrocolloid material; and a sensing unit configured to monitor one or more electrical properties between a pair of electrodes of the plurality of laser-induced graphene electrodes to detect moisture in the dressing material. The electrical properties may be electrical resistance, current or potential difference. The electrodes may be used for voltametric, amperometric or potentiometric measurements. The device may be a medical device such as an ostomy pouch, ostomy baseplate or extender film configured for use with an ostomy appliance.

[0022] In some embodiments, the sensing unit is configured to detect moisture if the monitored electrical resistance is less than a predetermined threshold resistance value. In some embodiments, the sensing unit is configured to monitor the electrical resistance constantly. In this way, moisture may be detected early and skin damage or leakage of fluid may be avoided or mitigated. In some embodiments, the sensing unit is configured to monitor the electrical resistance intermittently. In this way, the sensing unit may be efficient as a power consumption of intermittent monitoring may be less than the power consumption of constant monitoring. In some embodiments, the sensing unit is configured to monitor the electrical resistance in response to a request for a measurement. In this way, the device may monitor electrical resistance only when a user requires monitoring. Such an implementation may be used by a user to verify correct operation of an ostomy appliance, for example secure application of a pouch or baseplate.

[0023] In some embodiments, the sensing unit comprises an alarm configured to activate when moisture is detected. The alarm may alert the user to a deteriorating status of the dressing material, indicating a need for immediate or imminent replacement.

[0024] In some embodiments, the sensing unit is configured to record each instance of moisture detection. In this way, a user may review a frequency of moisture detection in a dressing material to plan timely replacement or detect physiological changes. Data pertaining to each instance of moisture detection may be stored in a memory associated with the device. For example, the device may comprise a memory configured to store the data. In other embodiments, the device may communicate recorded data with a further device, e.g., a user’s mobile phone, for storage.

[0025] In some embodiments, the sensing unit is configured to record, for each instance of moisture detection, at least one selected from the list: date; time; measured electrical properties. In this way, a user is provided with useful information in relation to the hydration or swelling of the dressing. The user may review the data to improve management of the dressing, for example, a user may determine a supply of replacement dressings required for an activity, allowing the user to accurately plan management of the dressing.

[0026] In some embodiments, the sensing unit is configured to characterise any moisture detected. In some embodiments, the sensing unit is configured to characterise any moisture detected by quantifying biomarkers in the moisture detected. In some embodiments, the sensing unit is configured to quantify biomarkers in the moisture detected. The biomarkers may be detected by measuring at least one selected from the list: pH; electrolyte content; antioxidant content. The detected biomarkers may be small molecules, pharmaceutical compounds, proteins or nucleic acids. Biomarkers may be measured using voltametric, amperometric, impedimetric or potentiometric methodologies as known in the art. The biomarkers may be molecules specific to a patient’s physiology or biochemistry, but also molecules arising through ingestion of food or medicines, or molecules arising from microbiological activities in the gastrointestinal system, for example. The detected moisture may be moisture within the dressing material or moisture that is on the dressing material, but not necessarily within the dressing material, or both.

[0027] The graphene electrodes within the dressing material could be used for a range of sensing applications within the layer or to obtain more diagnostic information about the ileostomy fluid inducing the swelling of the dressing. In some embodiments, the dressing material comprises a surface comprising an adhesive.

[0028] In some embodiments, the dressing material is configured to be disposed proximate a stoma and the sensing unit is configured to detect moisture in the dressing material proximate the stoma.

[0029] According to another aspect of the invention, there is provided a skin barrier for an ostomy appliance configured to detect leakage from a stoma, the skin barrier comprising: a stoma aperture configured to receive a stoma; and the device for detecting moisture according to an aspect of the invention disposed proximate the stoma aperture; wherein the device for detecting moisture is configured to detect moisture proximate the stoma.

[0030] The skin barrier may form part of an integrated ostomy appliance, such as a pouch. Alternatively, the skin barrier may form part of an ostomy baseplate to which a pouch may be affixed.

[0031] Any feature or features described in relation to any aspect, embodiment or example may be combined with any one or more features of any other aspect, embodiment or example.

[0032] Brief Description of the Drawings

[0033] The invention will be described by way of example only referring to the figures, in which:

[0034] Figure 1 shows a flowchart of a method for forming a laser-induced graphene deposit in a dressing material according to an embodiment of an aspect of the invention;

[0035] Figure 2 shows a schematic representation of the method for forming a laser-induced graphene deposit in a dressing material according to an embodiment of an aspect of the invention; Figure 3 shows electron micrographs of a dressing material before and after undergoing the method for forming a laser-induced graphene deposit of Fig. 1 ;

[0036] Figure 4 shows a dressing material comprising laser-induced graphene electrodes according to an embodiment of a further aspect of the invention; and

[0037] Figure 5 shows a device for detecting moisture in a skin barrier for an ostomy appliance according to an embodiment of a further aspect of the invention.

[0038] Detailed Description

[0039] Figure 1 shows a flowchart of a method 100 for forming a laser-induced graphene deposit, suitable for use as an electrode, in a dressing material according to an embodiment of an aspect of the invention. The method comprises: providing a dressing material 102; applying an absorber 104 to the dressing material; irradiating the absorber 106 with a laser such that a temperature of a portion of the dressing material proximate the absorber is increased thereby forming a graphene deposit in the portion of the dressing material.

[0040] The method further comprises removing the absorber 108 from the dressing material and irradiating the graphene deposit 110 with a laser to increase an extent of the graphene deposit in the dressing material.

[0041] Figure 2 shows a schematic representation of a method 200 for forming a laser- induced graphene deposit in a dressing material according to an embodiment of a first aspect of the invention.

[0042] Fig. 2 illustrates the steps of laser activated conversion of the upper most layers of a hydrocolloid film 202 into a conductive graphitic deposit 204 which can then be used as an electrode. Conventional laser treatment does not yield any graphitic deposit in hydrocolloid materials. In order to form the graphene deposit 204, the hydrocolloid 202 is first treated with an absorber 206 which interacts with the laser 208 and results in localised photothermal conversion of a portion of the hydrocolloid 202 to a graphene deposit 204. First, at 212, the hydrocolloid 202 is modified by adhering a film secondary layer 210 comprising a dark pigmented absorber 206 to a surface of the hydrocolloid 202. In other embodiments, applying an absorber 206 to the hydrocolloid 202 comprises applying an ink to a surface of the hydrocolloid 202. Upon activation of the laser 208 at 214, the pigmented absorber 206 absorbs laser energy and there is a localised rise in temperature with the conversion of the sp3 carbon atoms present in the hydrocolloid 202 to sp2 carbon, common to graphene materials.

[0043] At 216, as sp2 carbon begins to predominate at the top surface of the hydrocolloid 202, a conductive carbon deposit, graphene deposit 204, forms. The graphene deposit 204, once formation has been initiated, also serves as an absorber of the incident laser radiation and the conversion of sp3 carbon from the hydrocolloid to the sp2 conductive form is accelerated. Increasing a duration of the laser treatment increases an extent to which the hydrocolloid 202 is converted to laser induced graphene 204. The subsequent solvent removal of the absorber 206 and film secondary layer 210, at 218, reveals hydrocolloid 202 with laser induced graphene (LIG) deposit 204.

[0044] Figure 3 shows electron micrographs of a dressing material before and after undergoing the method for forming a laser-induced graphene deposit.

[0045] Discrete spots of laser induced graphene are formed in a dressing material using the method of the present invention. Providing discrete spots of laser induced graphene using the method of the present invention provides improved ease of manufacture and improved compatibility with appropriate sensing units when compared with conventional solutions. Electron micrograph A of Fig. 3 shows a hydrocolloid material before laser ablation. Electron micrograph B of Fig. 3 shows a hydrocolloid material after laser ablation. The laser induced graphene deposit is labelled LIG, and the surrounding unaltered hydrocolloid material is also labelled. Electron micrograph C of Fig. 3 shows a close-up view of the graphene deposit of electron micrograph B showing nano morphological features of the laser induced graphene deposit. Figure 4 shows a dressing material 402 comprising laser-induced graphene electrodes 404 according to an embodiment of a further aspect of the invention.

[0046] In Fig. 4, the laser induced graphene deposits 404 are used as a conductive electrode pair. In use, a current passing between the two electrodes 404 is used to detect the presence of moisture within the dressing material 402, for example, a hydrocolloid material. The electrodes 404 are embedded within the dressing material 402. In 406, in the absence of moisture, e.g., a stoma leak, a resistance measured between the two electrodes 404 is high and the sensing unit 408 does not detect moisture. In this case, an alarm is “off”.

[0047] In 410, as the dressing material 402 swells through contact with the stoma fluid 412, the presence of electrolyte within the dressing material reduces an electrical resistance between the electrodes 404 and a circuit is established. The sensing unit 408 detects moisture and an alarm is “on”.

[0048] Figure 5 shows a device 500 for detecting moisture in a skin barrier 502 for an ostomy appliance 504 according to an embodiment of a further aspect of the invention.

[0049] The skin barrier 502 of Figure 5 is shown around a stoma 506. A pouch 508 is configured to be affixed to the skin barrier 502. The skin barrier 502 adheres to the skin and provides a protective barrier around the stoma 506 which prevents damage to the underlying peristomal skin and avoids leakage of fluid from the pouch 508. A device for detecting moisture 500 is affixed to the skin barrier 502.

[0050] Bowel effluent leaking from a stoma 506, particularly from ileostomies where the effluent is largely water, may induce swelling of the dressing material, e.g., hydrocolloid material, of the skin barrier 502, which if left to progress, will cause gradual erosion. For example, a stoma flange comprising a hydrocolloid material may start to erode during use, exposing delicate peristomal skin to damage. In many cases, leaks are directional, caused by a host of factors associated with the morphology of the stoma site, such as a recessed stoma, skin creases etc. Accordingly, an ostomy user may have a need to detect a moisture in a particular region of the skin barrier 502. The device 500 for detecting moisture comprises: a dressing material 510 comprising a plurality of laser-induced graphene electrodes 512; wherein the dressing material 510 comprises hydrocolloid material; and a sensing unit 514 configured to monitor an electrical resistance between a pair of electrodes 512 of the plurality of laser induced graphene electrodes 512 to detect moisture in the dressing material. As shown in Fig. 5, the dressing material 510 of the device 500 is configured to be disposed proximate a stoma 506 and the sensing unit 514 is configured to detect moisture in the dressing material 510 proximate the stoma 506.

[0051] In this instance, the dressing material is an extender film 510 which is disposed at a periphery of the skin barrier 502. The extender film 510 is curved to co-operate with a shape of the skin barrier 502 and is disposed further from the stoma 506 than an interface between the pouch 508 and the skin barrier 502. The extender film 510 may be disposed by a user in a location around the stoma 506 to detect moisture of a known directional leak or common erosion path. In this way, a compact system may provide a user with sufficient moisture detection without being disposed around an entire circumference of the skin barrier 502.

[0052] The extender film 510 comprises electrodes 512 formed of laser induced graphene according to an aspect of the invention. The electrodes 512 are connected to a sensing unit 514 by wires 516. The extender film 510 may be affixed to the skin barrier by an adhesive provided on a rear surface of the extender film, that is, a surface opposite a surface comprising electrodes 512.

[0053] The extender film 510 may be placed so that the electrodes 512 are disposed where leakage commonly occurs. As the skin barrier 502, and hence the extender film 510, swells, a circuit is established between the electrodes 512 which registers an alert such that the user may replace the pouch 508 before a leakage occurs. As such, by detecting moisture and providing a warning alert, the present invention may reduce a risk of leakage of bowel effluent onto skin and / or clothing, as well as boost confidence and reduce anxiety relating to leakage. The sensing unit 514 is configured to detect moisture if the monitored electrical resistance is less than a predetermined threshold resistance value. The sensing unit 514 may be configured monitor the electrical resistance constantly, intermittently and / or in response to a request for a measurement. The sensing unit 514 may be configured to record, for each instance of moisture detection, a date, time and / or measured resistance. The sensing unit 514 comprises an alarm configured to activate when moisture is detected.

[0054] Further, the sensing unit 514 may be configured to characterise any moisture detected, for example, by quantifying biomarkers, such as pH, electrolyte content and / or antioxidant content, in the moisture detected. The detectable biomarkers may be small molecules, pharmaceuticals, proteins or nucleic acids, for example. For example, the biomarkers may be H+(pH), H2S, CO2, NH3, H2O2, vitamins, purines (xanthine, hypoxanthine and urate), creatine / creatinine and macromolecules such as calprotectin, lactoferrin, which are of significance for bowel inflammation. Further, the biomarkers may be drugs such as paracetamol or NSAIDS such as 5-aminosalicylic acid.

[0055] In an alternative embodiment, the skin barrier 502 for an ostomy appliance may be configured to detect leakage from a stoma 506, the skin barrier 502 comprising: a stoma aperture configured to receive a stoma 506; and the device 500 for detecting moisture disposed proximate the stoma aperture; wherein the device 500 for detecting moisture is configured to detect moisture proximate the stoma 506.

[0056] The invention will now be described by way of the following example.

[0057] Example

[0058] Laser-induced graphene (LIG) was produced on the hydrocolloid flange extender using a laser power of 60% or 80% of a 5 W laser diode with a wavelength of 455 nm, at a raster speed of 2000 mm / minute and a line scan density of 3 lines / mm. The flange extender was lowered an additional 15mm away from the laser to defocus the beam at the lasing site and three full passes of the laser were performed over the target area. The flange extenders themselves had a top coating of polyurethane, which acted to lens the laser beam through the hydrocolloid and ablate material under the sample. Therefore, black ink was applied to this top surface coating using a black marker pen so it would absorb the energy from the laser instead of letting it pass through. This meant that the first pass of the laser stripped off the top polymer coating, and exposed the hydrocolloid which was then converted to LIG with the two subsequent passes of the laser.

[0059] As will be understood by the skilled person, the example embodiments presented above can be modified in a number of ways without departing from the scope of the invention. For example, the device for detecting moisture may form part of a single piece system, an integrated ostomy appliance, or a two-piece system, for example comprising a baseplate and pouch. Alternatively, the device for detecting moisture may be a standalone device configured for use with any other suitable device in relation to stoma management or otherwise.

[0060] The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS1 . A method for forming a laser-induced graphene deposit in a dressing material, wherein the graphene deposit is suitable for use as an electrode, the method comprising: providing a dressing material; applying an absorber to the dressing material; irradiating the absorber with a laser such that a temperature of a portion of the dressing material proximate the absorber is increased thereby forming a graphene deposit in the portion of the dressing material.

2. The method of claim 1 , wherein applying an absorber to the dressing material comprises applying an ink to a surface of the dressing material.

3. The method of claim 1 , wherein applying an absorber to the dressing material comprises adhering a film to a surface of the dressing material.

4. The method of any preceding claim, wherein the absorber is dark pigmented.

5. The method of any preceding claim, wherein the dressing material comprises hydrocolloid material.

6. The method of any preceding claim, further comprising removing the absorber from the dressing material.

7. The method of claim 6, wherein removing the absorber from the dressing material comprises dissolving the absorber using a solvent.

8. The method of any preceding claim, further comprising irradiating the graphene deposit with a laser to increase an extent of the graphene deposit in the dressing material.

9. The method of any preceding claim, wherein, when a temperature of the portion of the dressing material is increased, sp3 carbon in the dressing material isconverted to sp2 carbon thereby forming a graphene deposit in the portion of the dressing material.

10. A laser-induced graphene electrode in a dressing material obtainable by the method of any preceding claim.

11. A dressing material comprising a laser-induced graphene electrode, wherein the dressing material comprises hydrocolloid material.

12. The dressing material of claim 11 , wherein the electrode is embedded within the dressing material.

13. A device for detecting moisture comprising: a dressing material comprising a plurality of laser-induced graphene electrodes; wherein the dressing material comprises hydrocolloid material; and a sensing unit configured to monitor an electrical resistance between a pair of electrodes of the plurality of laser-induced graphene electrodes to detect moisture in the dressing material.

14. The device of claim 13, wherein the sensing unit is configured to detect moisture if the monitored electrical resistance is less than a predetermined threshold resistance value.

15. The device of claim 13 or claim 14, wherein the sensing unit is configured to monitor the electrical resistance constantly.

16. The device of claim 13 or claim 14, wherein the sensing unit is configured to monitor the electrical resistance intermittently.

17. The device of any one of claims 13 to 16, wherein the sensing unit is configured to monitor the electrical resistance in response to a request for a measurement.

18. The device of any one of claims 13 to 17, wherein the sensing unit comprises an alarm configured to activate when moisture is detected.

19. The device of any one of claims 13 to 18, wherein the sensing unit is configured to record each instance of moisture detection.

20. The device of claim 19, wherein the sensing unit is configured to record, for each instance of moisture detection, at least one selected from the list: date; time; measured electrical properties.21 . The device of any one of claims 13 to 20, wherein the sensing unit is configured to characterise any moisture detected.

22. The device of claim 21 , wherein the sensing unit is configured to characterise any moisture detected by quantifying biomarkers in the moisture detected.

23. The device of claim 22, wherein the sensing unit is configured to quantify biomarkers in the moisture detected by measuring at least one selected from the list: pH; electrolyte content; antioxidant content; small molecules; pharmaceutical compounds; proteins; nucleic acids.

24. The device of any one of claims 13 to 23, wherein the dressing material comprises a surface comprising an adhesive.

25. The device of any one of claims 13 to 24, wherein the dressing material is configured to be disposed proximate a stoma and the sensing unit is configured to detect moisture in the dressing material proximate the stoma.

26. A skin barrier for an ostomy appliance configured to detect leakage from a stoma, the skin barrier comprising: a stoma aperture configured to receive a stoma; and the device for detecting moisture of any one of claims 13 to 25 disposed proximate the stoma aperture;wherein the device for detecting moisture is configured to detect moisture proximate the stoma.

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