goal, a scalable process for realizing a large number of sensors over large areas with mechanical flexibility is necessary. Printed flexible and stretchable electronics envisage a drastic change in production methods, but more importantly how elec tronics are perceived and implemented. [7] In applications where thin, flexible, and stretchable properties are required, printed sensors detecting a multi tude of para meters represents an elegant solution. [8][9][10][11][12] Accurate measurement of tempera ture is of critical importance. Measuring temporal changes in temperature or spatial temperature gradients is exten sively used in industrial settings as well as for medical applications. Recently there is an increased interest in equipping complex surfaces and shapes with a large number of temperature sensors. [7,13,14] This requires a costefficient route to manufacture thermistor materials over large areas on flexi ble substrates.Thermocouples are the classical instru ment for measuring temperature, where changes in resistance of a metal is used to determine the temperature. The drawback of this method is the limited change in resistance (+0.1% °C −1 ) and the need to compensate for the cold junction temperature, making accurate measurements challenging, costly, and sensitive to artifacts. [15] Resistance temperature detectors (RTDs) represent another Surfaces which can accurately distinguish spatial and temporal changes in temperature are critical for not only flow sensors, microbolometers, process control, but also future applications like electronic skins and soft robotics. Realizing such surfaces requires the deposition of thousands of thermal sensors over large areas, a task ideally suited for printing technologies. Negative temperature coefficient (NTC) ceramics represent the industry standard in temperature sensing due to their high thermal coefficient and excellent stability. A drawback is their complex and high temperature fabrication process and high stiffness, prohibiting their monolithic integration in large area or flexible applications. As a remedy, a printable NTC composite that combines a rapid and scalable all-printed fabrication process with performances that are on par with conventional NTC ceramics is demonstrated. The composite consists of micrometer-sized manganese spinel oxide particles dispersed in a benzocyclobutene matrix. The sensor has a B coefficient of 3500 K, with a 4.0% change in resistance at 25 °C, comparable to bulk ceramics. The selected polymer binder yields a composite exhibiting less than a 1 °C change in resistance to changes in humidity. The sensor's scalability is validated by demonstration of a A4-sized temperature sensing sheet consisting of over 400 sensors.
