Scientists have created a smart bandage they say can detect bedsores long before they become visible.
Bedsores can develop when a patient is laid up in bed - prolonged pressure hampers blood flow, damaging the skin.
The sticking plaster uses electrical currents to detect early tissue damage as pressure ulcers start to form.
Animal testing suggests a prototype works as a warning system. Human trials are now needed to test these findings, Nature Communications reports.
About half a million people a year in the UK develop at least one pressure ulcer, often in hospitals and nursing homes.
And they can lead to serious complications, including infection of the skin, bones, joints and blood.
Cell damage or death changes the structure and integrity of the cell membrane or outermost layer, allowing more electrical current to pass through. This is what the smart bandage detects.
Prof Michel Maharbiz and his team at the University of California Berkeley hope their device will be built into bandages and wound dressings.
He said: "You can imagine a future which is very close, where the bandages that you put on or the dressing that a surgeon or physician might put on would actually be able to really report on a lot of interesting information about the progress of the wound."
NHS England says most pressure ulcers are avoidable, given the right care and early detection.
A spokeswoman for the Royal College of Nursing said: "Pressure ulcers are both painful and distressing, but can be preventable.
"The cornerstone of prevention is risk assessment and mitigation which requires adequate numbers of skilled nurses both in the community and in hospitals"