Light-excited chemiresistive sensors integrated on LED microchips

Abstract

With the rapid development of the internet of things, light-excited gas sensors have aroused great attention to meet the increasing demand for room-temperature devices with high portability and low power consumption. However, there are still many issues that need to be addressed, especially the lack of tailored structures specifically designed for light-excited gas sensors. In this work, ∼2600 PIC micron-scaled gas sensors and LED UVC light sources were integrated on a 2-inch sapphire wafer. The integrated microchip exhibited an excellent gas-sensing response to NO₂ under in situ light excitation. The response of the device to 500 ppb NO₂ was S = 1.12 and its response to an ultra-low concentration of 10 ppb NO₂ was S = 1.01. The device exhibited a low resistance at the kΩ-level and fast response and recovery time of 30 s and 88 s, respectively, to 500 ppb NO₂, making it ideal for portable applications at room temperature. Moreover, its sensing properties could be tuned by adjusting the wavelength and irradiance of the LED layer. This work lays the foundation for the fabrication of integrated multi-functional devices.