Anagrafe della ricerca

Body temperature (BT) is one of the most important vital signs for evaluating human health. Abnormal BT patterns are key indicators for the prognosis of various illnesses and the most common symptoms of defensive immune responses. The early identification of these patterns, however, requires systems capable of continuous monitoring of the core body temperature (CBT). This task cannot be pursued by simple wrist bracelets or single skin temperature probes that can largely underestimate the value and fluctuations of CBT, which is instead typically measured by invasive thermometers. A possible strategy to improve the prediction accuracy of skin temperature measurements entails the use of multiple probing points with insulated temperature sensors to mitigate environmental effects and prevent local heat loss at the measured site. Early attempts towards this goal have involved multiple thermistors connected to a fixed measurement setup, thus mitigating the discomfort of the patients, but not solving the issues of low system portability and flexibility. Thus far, exploratory solutions in this direction relied on stitchable and flexible devices based on adhesive thermistors, conductive materials whose resistance changes as the temperature is varied. Despite the conceptual simplicity of this method, the need to conformally adapt to the skin introduces a significant challenge: the stretchable conductor needs to consistently retain its sensitivity upon large and frequent stretching events. THERmIR proposes an alternative solution that relies on the development of wearable and stitchable optical temperature sensors, capable of monitoring skin temperature by harvesting the infrared radiation emitted by the human body, whose emissivity spectrum is maximum in the mid-infrared (mIR) range. We will employ large-area graphene grown by chemical vapor deposition as the active material to devise efficient optical temperature sensors. This strategy allows for the scalable realization of skin-like, flexible, non-invasive thermometers that can be applied to multiple locations on the skin, minimizing the discomfort and maximizing the system efficiency and portability. The three research units involved in the project will gather their complementary expertise to pursue the research objectives: CNR will design, fabricate and characterize the high performance mIR photodetectors; POLITO will analyze the mIR absorption in graphene at a microscopic level and UNIVE will perform biocompatibility tests and quantify the thermometer’s figures of merit under flexural strain. We envision that the proposed technology will represent a solid building block for future medical diagnostics based on continuous BT monitoring, and also open new opportunities for applications in strategic domains, such as Internet-of-things sensors and wearable biometric platforms, where system accuracy, reliability and low SWaP (Size, Weight, and Power) are undisputed benefits.