A Unique Optical Temperature Sensor

By Aaryaa Padhyegurjar

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Optical-based sensors are tempting for temperature monitoring in biological diagnostics because of their advantages of remote detection, minimal intrusion, electromagnetic interference tolerance, and high resolution.

Dr He Ding of Beijing Institute of Technology’s School of Optics and Photonics, Professor Xing Sheng of Tsinghua University’s Department of Electronic Engineering, and colleagues developed an optoelectronic NIR-to-visible upconversion device with a linear response, rapid dynamics, and low excitation power based on devised semiconductor heterostructures.

The temperature-dependent photoluminescence features of the optoelectronic upconversion device are thoroughly investigated, and its capability for thermal sensing is demonstrated. A fully integrated optoelectronic upconversion device (Shown in the figure) based on a low-bandgap gallium arsenide (GaAs) based double junction photodiode and a large-bandgap indium gallium phosphide (InGaP) based light-emitting diode (LED) arranged in series is used in the proposed temperature sensing strategy.

(a) Circuit diagram and (b) Scanning electron microscopic (SEM) image of the optoelectronic upconversion design, including an InGaP red LED and a GaAs double junction photodiode with serial connection. (c) Schematic diagram of the upconversion device for temperature sensing. (Image Credit: He Ding and Team)
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“Through a large-area device array of the optoelectronic upconversion devices, we can perform spatially resolved thermal sensing. For example, we use air guns to generate hot airflow that blows on the sample, disturbs, and eventually extinguishes the upconversion emission. According to the relationship between emission intensity and temperature, we can obtain the spatial distribution and real-time changes of temperature,” says He Ding.

Xing Sheng from Tsinghua University stated, “The upconversion device can be released from the grown substrate and further integrated with fiber optics to form light-guided thermal sensors. Complementary with tethered electrical sensors, such an optical-based technique is more suitable for use in environments with strong electromagnetic interferences, and in particular, capable of obtaining signals during magnetic resonance imaging (MRI).”

“The MRI-compatible, implantable sensors combined with fiber optics offer both research and clinical significance, with a potential for localized temperature monitoring in the deep body. These materials and device concepts establish a power tool set with vast applications in the environment and healthcare,” Xing Sheng concluded and predicted.

The entire study is published here.



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