Is the wound worsening or is it healing? this new bandage can tell you

If bacteria invade our bodies from the wound, they will really threaten our lives unless they can be detected as soon as possible. Now, a new type of sensor that can be mounted on bandages alerts nearby bound smartphones when it detects that bacterial content has entered a dangerous range that needs to be alerted.

Healthy human skin is home to a large number of bacteria, and after the appearance of wounds, they quickly gather in skin wounds, such as Staphylococcus aureus (Staphylococcus aureus) and E. coli (Escherichia coli). Once bacteria spread in the body, they can cause death or permanent injury, so to prevent these microbes from entering the body, infected wounds may need to be cleaned or treated with antibiotics, or in the most extreme cases, severely infected limbs may need to be amputated.

In order to determine the infection of the wound, health care workers often need to remove the bandage, observe the wound, or wipe the wound with a cotton swab and collect samples for experimental testing. However, opening the bandage of the wound will delay the healing of the wound. In addition, observing wound infection is a subjective behavior, experimental tests take a long time, and both methods require the patient to be present in person.

To address these problems, some research teams are developing devices that can be placed on bandages to continuously monitor indirect signs of infection, such as changes in wound temperature or acidity. Now scientists at the National University of Singapore have developed a more direct sensor to monitor infection.

The sensor monitors an enzyme called deoxyribonuclease (DNase), the DNA enzyme. This enzyme can be used as a reliable indicator for monitoring infection, because pathogenic bacteria produce a large amount of DNA enzyme in the wound, while bacteria on healthy skin do not produce a large amount of DNA enzyme, so monitoring the content of this enzyme can reduce the probability of false positive results. In addition, DNA levels begin to increase before other signs of infection appear. Published in the journal Science Advances, the new alarm system is called a "wireless sensor for monitoring wound infection" (WINDOW sensor).

The enzyme content sensing component of the WINDOW sensor relies on an adhesive material called DNA hydrogel (DNAgel), which is mainly made up of wound DNA chains. In this study, the researchers designed a special DNA hydrogel that stays stable in humid environments such as human skin and begins to decompose when the DNA enzyme is detected.

In addition, they connected the gel to a chip, which sensed that the gel was breaking down and sent a signal to the smartphone. The signal is transmitted through a technology called near-field communication, a battery-free wireless technology that can be used in mobile payments.

John Ho, an electrical engineer at the National University of Singapore and co-author of the study, said: "by combining DNA hydrogel with sensor chips, we have created a device that can match bandages without batteries at all."

Therefore, if a person has a chronic wound or returns home after an operation, he or she can use the smartphone next to him to monitor his or her condition several times a day. Moreover, when the phone receives an alarm about infection, it will send a message to the doctor or remind the patient to return to the hospital for antibiotic treatment.

Other researchers have tried a number of ways to monitor infections, including high-tech imaging techniques that monitor the spread of bacteria and electronic noses that recognize chemical signals associated with infection. "in principle, there are many methods that are feasible." Said June Mercer-Chalmers of the University of Bath in the UK, who was not involved in the study. She is the project leader of the research group and has been involved in the development of a low-cost, ultra-fast swab test for testing infection.

Messer-Chalmers adds that, in fact, the key to all monitoring methods is whether they are practical: whether they require a lot of bulky equipment, whether there are difficulties in legal approval, and whether it is cost-effective. She also pointed out that WINDOW sensors require access to electronic components and smartphones, which may render some people and hospital systems unusable. Huo is hopeful about their method because each WINDOW sensor costs less than 64 yuan and can be made using existing electronic manufacturing processes.

So far, Huo's team has collected wound swabs from 18 diabetic patients with foot ulcers, some of whom are infected with Staphylococcus aureus. They then exposed the DNA hydrogel to the wound swab and observed the extent to which the gel material decomposed in the presence of bacteria. The researchers also used the sensor to test six living laboratory mice.

They exposed the wounds of the mice to the same bacteria and found that the sensor successfully detected infection within 24 hours before any signs began to appear. Currently, the WINDOW sensor is still in the early stages of development and testing, and Howe plans to continue testing on more patients, as well as other types of strains. "many different types of strains follow a similar mechanism to produce DNA, so this sensor should be used to monitor other types of strains infecting wounds," he said. "