Dressed to heal

Clinicians often face a dilemma when treating a patient with a wound dressing. Should they open the dressing to rule out infection or leave it intact to hasten healing? Removing the dressing can cause an abrasion, which may lead to a secondary wound, points out materials chemist Ramakrishnan Ganesan, Professor at the Hyderabad campus of the Birla Institute of Technology and Science, Pilani (BITS Pilani). On the other hand, if a wound infection is left untreated, it can lead to issues such as tissue destruction, delayed healing, bone infection and, in severe cases, sepsis, amputation, or even death. In patients with burn wounds, pressure ulcers, and diabetes, where tissue healing is slow and the risk of infection is high, this choice is critical to recovery.

For over 150 years, cotton gauze has been the standard dressing material for wounds. "(But) commercially available gauzes are hydrophilic and cannot remove the excess exudate and also interfere with the gaseous exchange at the site and hence delay the healing," says Jayati Ray Dutta, a microbiologist and Professor at the institute in Hyderabad. This necessitates periodic changes of dressing. To address this problem, Ganesan and Dutta have developed a smart bandage to help clinicians and patients make informed choices. This dressing is antibiotic-free yet kills germs, helps drain wound exudate, does not stick, and changes colour to warn of an infection.

A combination of factors — an ageing population, rising incidence of diabetes and antibiotic-resistant microbes, and overstrained medical staff — has increased the demand for bandages that support wound management by monitoring and treating injuries. The smart bandage market, which was valued at around $1 billion in 2025, is expected to grow at a compounded annual growth rate of 9.66% from 2026 to 2035, according to the consultancy firm Precedence Research (bit.ly/Smart-Bandage-Market).

Wounds can be monitored using physiological and biological parameters. A high temperature signals inflammation and indicates an early infection. High pH delays healing and is another sign of early infection. Moisture levels help determine if the wound is too dry to heal or so wet that there is a risk of infection. Biomarkers that detect bacterial toxins and inflammatory markers can also shed light on a wound.

In the past decade, the availability of light, flexible sensors and biosensors that can record these parameters, and wireless technologies that easily relay the results to mobile apps for remote monitoring, have boosted the use of such bandages. Further, the availability of smart, stimuli-responsive materials and controlled drug-delivery systems is enabling wound infections to be treated without opening the dressing.

Various kinds of smart bandages are entering the market. France-based Grapheal has designed a bandage made of a smart material that heals wounds using electrostimulation, with biosensors that monitor the wounds and send results to an app. Similarly, researchers at the U.S.-based California Institute of Technology have developed iCares — a smart bandage that uses microfluidics, sensors, and machine learning for real-time wound management. Scientists from the National University of Singapore have engineered a bandage that detects temperature, pH, bacterial type, and specific inflammatory factors in chronic wounds within 15 minutes. Purdue University researchers have developed a low-cost, large-scale fabrication method using roll-to-roll manufacturing to print smart bandages that track key biomarkers, such as pH, temperature, and humidity, using sensors.

In India, Ganesan and Dutta started the project in 2022, after realising the problems posed by cotton gauze. They decided to use Poly(ε-caprolactone) (PCL) as the base for the dressing, since it does not stick and allows easy peeling. They used electrospinning techniques to convert this material into a mat of threads. The tiny gaps between these mat threads act like micro-capillaries that suck out the wound exudate. This electrospun mat also provides a large surface area for anchoring ionic silver and quaternary ammonium moieties directly onto the fibres. Antimicrobial silver obviates the need for antibiotics. On this base layer, the team created a hydrogel coating with three special chemicals: CPRG (chlorophenol red-β-D-galactopyranoside), nitrocefin, and IPTG (Isopropyl β-D-thiogalactopyranoside). When the silver kills the bacteria in the wound, bacterial enzymes are released and, due to capillary action, move to the top layer, where they come into contact with chemicals in the hydrogel. If the bacterial enzyme β-galactosidase interacts with CPRG and cleaves it, the colour changes from yellow to red, indicating infection. Similarly, if the enzyme β-lactamase —produced by antibiotic-resistant bacteria — comes in contact with nitrocefin, the colour changes from yellow to red. IPTG aids in both these enzymatic reactions (bit.ly/Bandage-Colours).

To test how well it works, the team treated porcine skin with varying bacterial concentrations, and then applied the bandage. The results showed that the bandage was antimicrobial, detected infection and relayed that by changing colours. "This smart dressing not only gives you protection, but it can also give you an indication," says Dutta, pointing out that patients can go for a dressing change when they see the colour change. The researchers are now looking forward to testing this bandage on humans and commercialising it through their Hyderabad-based start-up, DeepCure Tech.

While the BITS Pilani researchers addressed the issue of infection, a team led by Mitradip Bhattacharjee, an electrical engineer with a PhD in nanotechnology at the Indian Institute of Science Education and Research (IISER) Bhopal, along with scientists from the U.K., has developed a bandage that helps monitor both infection and healing. If a wound is infected or inflamed, the temperature around it rises; when the wound is healing, the skin contracts, signalling closure of the wound.

Bhattacharjee's team decided to make a flexible temperature and strain sensor that could be put on a dressing to monitor the wound. To develop strain sensors, they used Polydimethylsiloxane (PDMS), a transparent, stretchable, and flexible polymer, as the structural material. This polymer is filled with PEDOT:PSS or Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), a special conductive ink. When the bandage stretches, the PDMS polymer channel distorts, causing the ink to crack and obstructing the flow of electricity. This change in the flow of electricity signals whether the skin is stretched or loose. For a temperature sensor, a non-stretching PVC substrate was used, along with the PEDOT:PSS ink, which increased electrical conductivity as the temperature increased. The change in electricity gave a measure of the temperature and strain change. The electricity required for the working of these sensors is provided by an NFC (Near Field Communication) tag (bit.ly/Sensor-Electricity).

"The idea is if you have a wound, you put the bandage on top, you don't need to open it. You bring your mobile phone near the wound so that the NFC antenna will then transfer the sensor data to the mobile application," Bhattacharjee says. He adds that based on the data received, the clinician can decide whether the wound is healing well or intervention is needed. Bhattacharjee aims to add sensors and biomarkers to this smart bandage for more robust monitoring.

In 2020, researchers from the Guwahati-based Institute of Advanced Study in Science and Technology reported the development of a pH-responsive cotton patch bandage incorporated with jute carbon dots and a neem leaf extract. The hybrid bandage releases more of the antimicrobial neem leaf extract when the pH is 5 than when it is 7, as a low pH indicates a likely infection (bit.ly/Hybrid-Bandage).

Bandages may seem like a small cog in a hospital, but they are essential for healing. And the story is fast unravelling.

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