Thermal Sight: A Position-Sensitive Detector for a Pinpoint Heat Spot

Precise positioning is a never-ending goal in both fundamental science and technology. Recent decades of advancements in high-precision position detection have predominantly relied on photoelectric effects for light detection in semiconductors. Herein, a different approach is proposed: The thermoelectric-based position-sensitive detector (T-PSD) concept is designed to detect single heat spots arising from various energy sources, including electromagnetic radiation, electrons, and macroscopic mechanical heat. The T-PSD concept is initially derived mathematically from the fundamental principles of heat conduction and the Seebeck effect. Subsequently, it is proved by finite element simulation in both 1D and 2D configurations. Following this theoretical groundwork, T-PSD prototypes are fabricated and subjected to positional detection using various stimuli such as CO₂ laser beam, hot soldering tip, and electron beam. In the prototypes, structured aluminum-doped zinc oxide thermoelectric thin films, prepared via atomic layer deposition, are outfitted with voltage probes, enabling the measurement of thermoelectric voltages as a function of position and the intensity or temperature of the heat spot. Furthermore, practical decoding strategies are introduced to infer the position from the measured signals. The T-PSD in this article showcases considerable promise in high-precision position detection such as (quasi-)particle tracking and precision machinery, offering an alternative concept in PSD design.