A highly sensitive long-wave infrared detector that enables low-power, non-contact human-machine interaction was recently developed by a research team at the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) under the direction of Associate Professor Xiaowei Lu, Professor Peng Jiang, and Professor Xinhe Bao.
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On July 11th, 2022, the research was published in the journal Advanced Materials.
The human body emits thermal radiation. This radiation is predominantly in the long-wave infrared region (8–14 μm) and is characterized by low photon energy and low power intensity.
The photothermoelectric detector, which belongs to the category of thermal detectors, is well recognized for its broad spectral response in the uncooled and self-powered operating mode, which entails two distinct energy conversion procedures: photothermal and thermoelectric conversions.
The thermopile arrangement is frequently used in commercial photothermoelectric detectors to double the voltage signal, and the manufacture of these intricate micro-electro-mechanical systems is necessary. Due to the minimal voltage signal, an additional acquisition circuit with a high signal-to-noise ratio is typically used for detecting weak human radiation (around tens or hundreds of microvolts).
The SrTiO3-x/CuNi heterostructure served as the foundation for the researchers’ construction of a novel thermopile in this study.
This heterostructure effectively combined the high Seebeck coefficient of SrTiO3-x with the high electrical conductivity of the CuNi alloy. The combination of free carrier and phonon resonance absorption, on the other hand, gave this heterostructure the capacity for broad-band optical absorption.
The SrTiO3-x/CuNi-based thermopile showed considerable sensitivity to human radiation as a result of these characteristics. The noise voltage was 10 nV/Hz1/2 and the output signal level went up to 13 mV. The noncontact real-time recognition of hand motions, Arabic digits, and alphabet letters was further implemented using a thermopile array.
This work offers a reliable strategy to integrate the human radiation into noncontact human-machine interaction, which may play vital roles in certain human-machine interaction fields where hygiene and security become crucial concerns.
Peng Jiang, Professor, Dalian Institute of Chemical Physics, Chinese Academy of Sciences
Guo, X., et al. (2022) SrTiO3/CuNi-Heterostructure-Based Thermopile for Sensitive Human Radiation Detection and Noncontact Human–Machine Interaction. Advanced Materials. https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202204355