Based on a flexible, self-sustaining thermoelectric system, this device created by a URV-led research team can monitor wounds and lesions

An international team led by researchers from the Universitat Rovira i Virgili (URV) has developed an innovative piece of equipment in the field of medical technology: an intelligent device capable of monitoring the temperature of the skin continuously and accurately. The device uses a thermoelectric system that works without batteries or an external power supply to detect temperature variations associated with inflammation and infection. The results of the project have been published in the journal Advanced Science.

The device was created as part of a European project in collaboration with researchers from the University of Porto, who specialise in energy recovery systems. The initial aim of this research was to increase the autonomy of sensors used in medical and industrial environments. “The idea was to avoid dependence on batteries and to create flexible devices that could be adapted to the skin or other surfaces,” explained Eduard Llobet, a researcher at the URV’s Department of Electronic, Electrical and Automatic Engineering.

Temperature as a key indicator

Temperature is an essential indicator for the early diagnosis of wounds and inflammatory processes in the skin. Local temperature variations can reveal infections, healing problems or other unhealthy alterations. Until now these diagnoses were carried out with infrared cameras or point sensors, but the problem with these techniques is that they require the patient to be immobilised and cannot monitor the entire skin surface.

This research marks a step forward. The device is able to precisely measure small changes in temperature and to identify specific points of inflammation thanks to its structure, which is based on a network of thermocouples. These are unions of semiconductor materials that generate an electrical signal when they detect differences in temperature. According to Llobet, “it is like creating a thermal map of the skin, with points that indicate where there is an affected area”.

The device has been validated through numerical simulations and experimental tests on human skin, even under sweaty conditions using a saline solution to simulate perspiration. The tests have shown that it can detect temperature variations as small as 0.4°C and that it responds in less than three seconds to changes in temperature. This allows the evolution of a wound to be monitored in real time and any signs of infection to be detected quickly.

Pioneering and sustainable technology

The device is based on flexible thermoelectric materials combined with a conductive polymer printed using techniques similar to those used in the printing of t-shirts. This means it can be manufactured on flexible polymeric substrates that can adapt to the skin without difficulty. “This configuration is not only more precise than traditional sensors, but also more resistant to external interference, for example through sweat or the movement of the skin,” said the researcher. The researchers also tested the durability of the device. The URV’s Department of Mechanical Engineering subjected the sensors to hundreds of bending cycles to see if they deteriorated with use. “The results have been very promising, because we have shown that the sensor retains its functionality even after multiple deformations,” said the head of department, Silvia de la Flor, who also participated in the research.

Easy to interpret and open to new applications

Furthermore, the information provided by the sensor is easy to interpret: “The system can display a colour map with temperature gradients, and this means that, without needing to be trained, healthcare staff can quickly identify the affected areas” said Llobet. This facilitates clinical decision-making and the proactive management of patient health.

The device can be worn for several days before being replaced and in this regard it is similar to conventional techniques. “The idea is that it can be worn like any other device without affecting the person’s comfort,” says De la Flor.

This technological breakthrough opens the door to more personalised and accessible medicine. The sensor can help not only to prevent infections in surgical wounds and pressure ulcers, but can also be adapted to other applications such as the monitoring of inflammatory processes or for use in medical packs.

The research team is already working on new projects to expand the functionalities of the device, such as the incorporation of biosensors to measure other physiological variables, for example levels of dissolved gases or specific biomarkers. “Our idea is to continue developing this technology to make it even more versatile and useful in the clinical setting,” they concluded.

Reference bibliogràfica: Almeida MAS, Pires AL, Ramirez JL, Malik SB, de la Flor S, Llobet E, Pereira AT, Pereira AM. Touch Empowerment: Self-Sustaining e-Tattoo Thermoelectric System for Temperature Mapping. Adv Sci (Weinh). 2025 Feb;12(7):e2403775. doi: 10.1002/advs.202403775. Epub 2024 Dec 26. PMID: 39724383; PMCID: PMC11831475.