An intelligent bandage that can monitor the humidity of a wound in real time, which can only be changed when needed without interfering with the healing process. This is the idea proposed in Frontiers in Physics by a group of Italian researchers from the University of Bologna, designed above all to solve the problem of chronic wounds in bedridden patients with bedsores and diabetics.
The wound healing process depends on a series of factors that contribute to building a favorable environment for the reconstruction of damaged tissues. These include the Ph of the region, the level of hydration, the amount of uric acid, the infectious state and the levels of lactate and glucose. The most decisive of these is hydration: a wound that is too dry will dry the tissues, one that is too wet (as in the case of blisters, burns or chronic sores) will make them too soft – as happens when you spend too much time in the water. Today, the state of tissue hydration is visually assessed by doctors, and involves the removal of the bandage and, with it, the risk of damaging the wound itself and interrupting healing.
In the study, the researchers devised a plaster capable of detecting the degree of moisture in the wound and communicating it in real time directly to the smartphone, quickly and wirelessly. The essential element of this new method is the inclusion of a conductive polymer in the gauze that is placed in contact with the wound. The choice is not easy, since the material must be skin-compatible and the link between the state of the wound and the electrical signal detected by the sensor (ie, the electrochemical response of the material used) must be clear.
How the new patch works
“The sensor is made from an easily available commercial polymer supplied in an aqueous solvent,” says Marta Tessarolo, researcher at the University of Bologna and first author of the study. “It can be used as an ink and printed on gauze and other fabrics just like screen prints on T-shirts. The geometry of the sensor can be adapted to the size of the patch without any difficulty. In the article we have shown that the sensor’s performance does not change significantly when bent, and they are always able to distinguish a wet wound from a dry one ”.
The material the researcher talks about is called poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS), an organic semiconductor polymer applied to a gauze using the screen printing technique. The gauze is then incorporated into a patch along with an inexpensive, disposable sensor similar to those used for anti-theft clothing tags. The sensor can communicate moisture level data directly to a smartphone, letting healthcare professionals know when a bandage needs to be changed.
“The sensor consists of two electrodes placed at a known distance from each other” explains Tessarolo. “When the exudate (the liquid that escapes from the tissues, ed) from the wound wets the patch, the impedance measured between the two electrodes decreases drastically. This sudden change in impedance makes it possible to drive a radiofrequency identification technology (RFID) or NFC (Near Field Communication) which performs an on / off measurement: wet / dry. Both methods work with a simple tag similar to that used in clothes that allows the wireless data from an RFID reader or from an app of a mobile phone with NFC technology ”.
Towards personalized care
The new patches were tested on an artificial exudate similar to that of a wound and varying in intensity, and different materials and shapes of the patches were evaluated. The results showed that the PEDOT: PSS polymer-based bandage is highly sensitive to the percentage of moisture and provides drastically different readings for dry, moist and saturated fabrics. This is valuable in optimizing the management of wounds of various types, from those that ooze slowly to those that lose a lot of fluid – such as burns or blisters. This is a step towards personalized medicine also in this area, where the risk is that a non-optimal treatment will make the problem chronic. Lastly, no less important is the attention of researchers to the costs and, therefore, the accessibility of the new method.
“We believe that given the low cost of the material and the ease of fabrication of the RFID / NFC tag, our patch has good potential to be mass produced. It could be suitable for both hospital and personal use, remotely sending, for example, the data acquired to the competent doctor via the app ”, concludes the researcher.
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