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Introduction Maintaining the correct temperature of blood products during storage and transport is critical for patient safety, particularly in emergency and field operations. However, currently available systems rely on active, battery-powered thermometers, which require regular maintenance and are susceptible to power failure. The research question we address is: Can a fully passive, RFID-based temperature sensor be developed to reliably detect critical temperature thresholds in blood products without the need for batteries or infrastructure?Methods In collaboration with Aalen University and the Deggendorf University, a novel sensor material is being developed that changes its electrical properties irreversibly upon exposure to infrared (IR) or ultraviolet (UV) radiation, which correlates with environmental temperature or sunlight. This material integrates cumulative exposure, making it possible to assess both intensity and duration of thermal impact. The focus is currently on changes in ohmic resistance: a fresh sensor exhibits low resistance, while a ‘expired’ sensor shows high resistance. The change is irreversible, providing tamper-proof evidence of temperature violations. An RFID chip mounted on top of this coating reads the resistance state and transmits the data wirelessly ( figure 1). Attempts to remove the sensor—for example, scraping it off the blood bag—result in infinite resistance, which the system interprets as an invalid or expired product. This enhances system security and authenticity.Results Preliminary lab tests have confirmed that the sensor material exhibits a measurable and irreversible change in electrical resistance following defined IR or UV exposure levels. The resistance value reliably reflects cumulative environmental impact. The RFID interface can read and report this state in real time using standard readers, such as handheld or tablet-integrated devices. Upcoming testing will focus on verifying sensor performance under simulated transport and storage conditions. Metrics such as detection accuracy, sensor stability, false positive/negative rates, and shelf-life behaviour will be evaluated. The final aim is to demonstrate non-inferiority compared to active, battery-powered thermologgers and to validate the sensor’s suitability for operational use in military and emergency medical contexts.Discussion BlutSens offers a novel approach to temperature monitoring of blood products and medication. Unlike conventional solutions, it does not require batteries, calibration, or ongoing maintenance. It functions completely independently of external infrastructure and IT systems. This makes it particularly suited for emergency and field applications. Moreover, the ability to monitor individual product units rather than entire boxes increases both safety and cost-efficiency. The technology enables immediate, reliable readouts at any point during the product’s lifecycle, thereby significantly enhancing transparency and accountability in supply chains.Conclusion The BlutSens system has the potential to redefine temperature monitoring for medical products by providing a passive, infrastructure-independent, and cost-effective solution. Planned studies will validate its efficacy compared to standard approaches and explore its operational benefits for both military and civilian emergency medicine.Abstract A07 Figure 1Schematic illustration of the BlutSens RFID tag and sensor layer applied on a blood product label. The RFID reader identifies whether a temperature threshold was exceededPatient and Public Involvement The development of BlutSens has been guided by feedback from end users in both civilian and military medical services. Operational requirements and field usability were defined in close collaboration with the German Armed Forces and selected emergency medical service providers. Their input has shaped sensor form factor, label integration, and readout logic to ensure high acceptance and practical value.Funding and Disclosure The BlutSens project is funded by the German Federal Ministry for Economic Affairs and Climate Action under the ZIM program (funding reference: KK5690001JN4). Project partners include Aalen University and Technische Hochschule Deggendorf. The authors declare no conflicts of interest. The project has been reviewed and approved by the sponsoring authority.