Flexible thermoelectric film sensor for optical power detection and multi-modal sensing

With the rising need for advanced optical sensing, conventional rigid sensors often lack precision and versatility. Here, we report a highly sensitive and flexible photothermoelectric device array with a radial architecture, fabricated via magnetron sputtering using n-type Bi 2 Te 3 and p-type Sb 2 Te 3 . Based on the photothermal conversion and the Seebeck effect, the device achieves exceptional optical-power detection accuracy, demonstrating a strong linear correlation between photovoltage and incident power with an error margin below 1.5%. It exhibits stable photothermoelectric switching and a fast response time of ∼3 s, enabling real-time laser monitoring and threshold alerts. Using a fixed-area Cu electrode as current collector and photothermal absorber eliminates extra absorber layers, cutting material cost and fabrication steps. Integrated into wearable devices, the array enables motion tracking, Morse code communication, and respiration monitoring, offering a versatile high-precision platform for next-generation optical health devices.