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A DIAGNOSTIC SKIN PATCH WITH A THERMOCHROMIC INDICATOR AND A DIAGNOSTIC SURGICAL FACE MASK WITH A THERMOCHROMIC INDICATOR
Technical Field
[0001] The invention further concerns a diagnostic skin patch.
[0002] The invention may also include a surgical face mask conventionally worn over the mouth and nose of a user to protect the wearer from aerosols, ie airborne droplets of water or mucus which may contain pathogens or toxins. They are also worn to prevent the wearer shedding pathogens, such as virus particles which may be suspended in vapour droplets or mucous by exhalation into the air, thereby exposing others to the risk of contagion. Due to several recent pandemics including Covid 19, MERS, and other viral infections concern over the latter problem has escalated and efforts to identify potential victims as early as possible and thereby facilitate isolation of the victims to reduce contagion is at a heightened level.
Prior Art
[0003] Patches for application to the skin of a user are known for a number of therapeutic and cosmetic purposes. Most commonly the patch consists of a thin flexible membrane with an adhesive layer laminated onto one side. The patch is bonded to a substrate which prevents the adhesive layer setting and facilitates handling. The substrate may be a layer of waxed paper or more commonly a sheet of plastics material. To use the patch, the patch is peeled from the substrate and the adhesive layer bonded to the skin of the user. Such patches commonly contain compositions such as nicotine or therapeutics for the treatment of a medical condition. 10004] A surgical mask is essentially a sheet filter material. The preferred filter material is a non-woven fabric commonly made by melt blowing nanofibers or microfibres. The sheet is cut to a desire size and pattern, commonly a rectangle, pleated and a fastening means is attached. The fastening means is most commonly two loops of ribbon extending from opposing edges to attach by looping over the ears of a user to retain the mask in place over the nose and mouth. In some cases a nosepiece in the form of a plastic strip may be provided to shape over the bridge of the user’s nose.
Summary of Invention
[0005] According to a first aspect of the present invention there is provided a diagnostic patch comprising: a substrate film; a layer of adhesive coating one skin side of the film suitable for bonding to the skin of a user; a pattern of inks including a thermochromic ink applied to at least one surface of the film whereby when the thermochromic ink reaches a critical colour change temperature the colour and or the pattern appears to change to an observer.
[0006] Preferably the critical temperature is a skin temperature indicating that the user is feverish, this will preferably be a temperature of 37.5C. A first pattern of non-thermochromic ink is applied to be visible to an observer when the patch is bonded to a user’s skin. This will preferably be applied to an outer surface of the film, ie the surface opposite an inner layer which will be coated with adhesive. However, if the film is transparent the first pattern may be applied to the inner layer prior to applying the adhesive coating. The second layer of thermochromic ink is applied to the outer layer overlying and obscuring at least a part of the first layer and preferably wholly overlying the first layer. Preferably the pattern of the second layer will corresponding in shape to the first layer. Preferably the pattern is a pattern of lines.
[0007] The second layer of thermochromic ink is formulated to have a first low temperature colour which obscures the colour of the first ink pattern. However, if the temperature of the thermochromic ink exceeds a critical temperature it becomes transparent revealing the different colour of the first layer. Preferably the colour of the first layer is red and the colour of the second layer is green.
[0008] Conveniently the patch may be provided bonded by the adhesive coating to a carrier film to which it is semi-bonded, ie it sticks but can be readily peeled off. Thus a patch can be peeled from the carrier film and stuck to a user by applying the adhesive coated surface to the skin of a user preferably where it is readily visible. The patch will acquire a temperature corresponding to the skin temperature of the user. If the user develops a fever the user’s skin temperature will rise above the critical temperature of the thermochromic ink.
[0009] Preferably a plurality of patches are supplied bonded to a single carrier sheet.
[0010] According to a second aspect of the present invention there is provided a method of making a diagnostic patch comprising the steps of: providing a substrate film; dividing the substrate film into notional patch areas; printing, onto a first surface of the substrate film, a first pattern of ink of a first colour one each onto each patch area; printing a second pattern of thermochromic ink onto the first surface to at least partially overly and obscure the first pattern; applying a layer of adhesive to the second surface of the substrate film opposite the first surface; bonding a carrier film to the second surface; cutting or kiss cutting the substrate film to divide the substrate film into patches ready for use. loon] According to a third aspect of the present invention there is provided a surgical mask comprising: a sheet of filter material; a pattern of inks including a thermochromic ink disposed in a central region of the sheet to lie in the path of exhaled air when in use, whereby the thermochromic ink undergoes a colour change if the exhaled air exceeds a critical temperature.
[00121 The critical temperature is an exhalation temperature indicating that the person using the mask is running a fever, that is to say the sensed body temperature of the user has exceeded 37.5 degrees Celsius. Because inhaled air is normally raised by heat exchange to body temperature the critical temperature of the thermochromic ink composition may be 37.5 C.
[0013] Preferably the pattern of inks comprises a first pattern of ink of a first colour applied to the central region of the sheet which will form the mask. The ink used to form the first ink pattern may not be thermochromic and is preferably red in colour. A second pattern of thermochromic ink is disposed to at least completely overly and obscure the first pattern. Preferably the second pattern of thermochromic ink has a low temperature colour of green and a high temperature colour of clear. The difference between low and high temperature in this case is determined by the formulation of the thermochromic ink to be the critical temperature, preferably 37.5C. Thus in air exhaled by the user impinges on the central region of the mask and therefore raises the central region and the pattern of thermochromic ink to a temperature correlating to the body temperature of the user. At normal body temperature the pattern appears to be the low temperature colour of the thermochromic ink, eg green. If the user develops a fever temperature for any reason the exhaled air rises in temperature and heats the thermochromic ink above its critical temperature so that it become transparent. To an observer, the pattern of thermochromic ink appears to change to the first colour, red.
[0014] Preferably the first pattern is an arrangement of lines, and the second pattern is a similar arrangement of lines which may be of slightly greater thickness than the first pattern. This arrangement minimises the amount of thermochromic ink required and produces the maximum visual impact. Simply depositing a patch of thermochromic ink of the required composition onto the sheet will provide an indication but the critical colour change to transparent results in an apparently conventional appearance of mask which does not clearly indicate to the observer that the user is feverish.
[0015] According to a fourth aspect of the present invention there is provided a method of making a surgical mask comprising; notionally dividing a web of filter material into a plurality of sheet portions; applying a first pattern of ink of a first colour to a central region of each sheet portion; applying a second pattern of a thermochromic ink to overly the first pattern; cutting each sheet portion from the web.
[0016] Preferably each sheet portion is rectangular. The pleats may include the central portion of the mask. Preferably two ear piece ribbons will be bonded to opposing edges of the sheet to form loops for securing the mask in place. A plastic nose piece may also be bonded to a region of the sheet. loon] The patterns of ink may be applied by any of screen printing, contact printing or ink jet printing.
Brief Description of Drawings
[0018] Embodiments of a diagnostic patch and a surgical mask constructed according to the present invention will now be described, by way of example only, with reference to the accompanying figures: in which,; figure 1 is a plan view of a patch; figure 2 is a left side sectional view of the patch; figure 3 is an enlarged fragmental sectional view of the patch; and figure 4 is a plurality of patches dispose on a carrier film figure 5 is a plan view of a sheet from which a face mask is formed with a first pattern; figure 6 is a plan view of the sheet from with a second pattern; figure 7 is a plan view of a pleated sheet; figure 8 is a left side elevation of the pleated sheet; figure 5 is an isometric south west view of a completed surgical mask
Detailed Description
[0019] A diagnostic patch is shown in figures 1 to 4. The patch comprises a substrate film 7 has a skin side coated with a layer of dermatologically compatible adhesive 8. A first pattern of non-thermochromic ink 9 is applied in the shape of a cross to the opposite outer side of the substrate film 7.
[0020] A second layer of opaque thermochromic ink 10 is printed onto the substrate film and over the first layer 9 in order to obscure the colour of the first layer. The second layer is coloured green.
[00211 To minimise ink usage and the mass of ink the cross pattern is made up of a pattern of thin straight lines rather than a solid mass. This also has the benefit of maximising the temperature responsiveness of the patch and allowing the patch to be maximally flexible to comply with the skin of the user without discomfort. Some user’s are likely to be mentally infirm and may seek to remove any irritating patch.
[0022] Multiple patches may be delivered on a single carrier film 11.
[0023] With reference to figures 5-9 a face mask is fabricated from a web of filter material divided into sheet portions 1. The sheet portion is rectangular and in this example has a length of 90mm and depth of 87 mm.
[0024] A first pattern 2 of non-thermochromic ink is printed onto a central region of the sheet.
In this case the pattern is a cross made up of lines of ink. The cross has a length and height of around 12mm and as indicated by the diagonal lines in figure 1 is positioned to be on the vertical centreline of the sheet and above the horizontal centre line of the sheet. The first pattern of ink is non-thermochromic and is coloured red in this case but may be of any colour.
[0025] A second similar pattern of thermochromic ink 3 is applied to overly the first pattern. The thermochromic ink in this case is coloured green when below its critical colour changing temperature. The second pattern is generally identical to the first pattern 2 in order to entirely obscure the red colouration of the first pattern.
[0026] Each of the first and second patterns are applied by silk screen printing.
[0027] In the next production stage the sheet 1 is folded repeatedly along the nine dotted lines shown in figure 2 to form three pleats 4 as shown in figure 3 and 4. The edges of the pleats are ultrasonically welded along the dotted lines 5 to fix them in place elastic ribbons 6 are secured to the corners of the sheet to form ear loops whereby the mask can be secured over the mouth and nose of a user by looping the ribbons over the ears of the user.
[0028] The patterns of ink are thus disposed in front of the mouth and nostrils of a user when the mask is worn so that air exhaled by the user impinges directly on the ink pattern. If the temperature of the exhalation rises as a consequence of a fever the second layer of ink 3 will exceed its critical temperature of 37.5 C and change from an opaque colour to transparent. This will reveal the red coloured first ink pattern underlying the second ink pattern.
[0029] The following paragraphs may further describe the surgical face mask: 10030] A surgical mask comprising: a sheet of filter material; a pattern of inks including a thermochromic ink disposed in a central region of the sheet to lie in the path of exhaled air when in use, whereby the thermochromic ink undergoes a colour change if the exhaled air exceeds a critical temperature.
[0031] A surgical mask according to para 30 wherein the critical temperature is an exhalation temperature indicating that the person using the mask is running a fever.
[0032] A surgical mask according to para 30 wherein the critical temperature is 37.5C.
[0033] A surgical mask according to paragraphs 30 or 31 wherein the second pattern of thermochromic ink is printed to completely overly and obscure the first pattern.
[0034] A surgical mask according to any one of paragraphs 30-33 wherein the pattern is made up of thin elongate lines to maximise the thermal responsiveness of the thermochromic ink and to minimise any mechanical impact the ink may have on the permeability of the filter material.
[0035] A method of making a surgical mask comprising; notionally dividing a web of filter material into a plurality of sheet portions; applying a first pattern of ink of a first colour to a central region of each sheet portion; applying a second pattern of a thermochromic ink to overly the first pattern; cutting each sheet portion from the web.