Intelligent Dressings: Finally coming of age?

The once and future promise of “theragnostics” in and around dressings may now be more “present” than “future” tense. To wit, here is a terrific article from this morning by Claire Bates and the UK’s Daily Mail:

The intelligent plasters that turn purple if wound is not healing properly


Scientists have created a hi-tech dressing that changes colour if the wound underneath becomes infected – thanks to a dye that can monitor changes in the body’s pH levels.

While our defence and repair system can heal small injuries within a few days, a gaping wound takes longer to close up and an infection can quickly take hold.

Dressings protect the site of the injury but to check the wound they have to be removed.

Dressing Indicates Infections
Dressing Indicates Infections

Purple patch: Healthy skin has a pH value of below five. The plaster reacts – via an indicator dye – by turning purple if the pH value increases above this level as it shows a possible infection

However, the specially designed bandages and plasters turn from yellow to purple if an infection is present.

This allows doctors to keep a check on an injury without having to change the dressing each time. It saves patients from unnecessary discomfort and also reduces the risk of germs entering the wound.

The intelligent material was developed by scientists at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT in Germany.

Lead researcher Dr Sabine Trupp, said: ‘We have developed an indicator dye which reacts to different pH values, and we have integrated it into a dressing and a plaster.

‘Healthy skin and healed wounds usually show a pH value of below five. If this value increases, it is shifting from the acid to the alkaline range, which indicates complications in the healing of the wound.

‘If the pH value is between 6.5 and 8.5 an infection is frequently present and the indicator colour strip turns purple.’

The pH scale measures how acidic something is on a scale of 0 to 14 with one being very acid, seven as neutral and 14 as very alkaline.

Dr Trupp said producing the colour control strip posed a number of challenges.

‘The dye has to remain chemically stable when bonded to the fibres of the dressing material or the plaster to ensure that it does not get into the wound,’ she said.

A prototype of the dressing has already been produced and the team said initial tests have been successful.

They will now trial the dressing at the University of Regensburg’s dermatology clinic and seek out a commercial partner.


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