High-consistency CO monitoring for neonatal jaundice breath analysis using CuO-in₂O₃ nanocubes grown in-situ on MEMS micro-hotplates

High-performance MEMS CO sensor based on in-situ grown CuO-In₂O₃ nanocubes, offering high response (1 to 50 ppm) and fast kinetics (11/45 s). • Excellent stability and reproducibility (2.02% deviation) achieved through robust in-situ growth on micro-hotplates. • A miniaturised wireless prototype demonstrates potential for portable, non-invasive neonatal jaundice monitoring. Accurate detection of carbon monoxide (CO) concentrations in the exhaled breath of newborns with jaundice is crucial for early diagnosis of the condition. However, the consistency and integration of existing sensors are often constrained by inherent limitations in their manufacturing processes and material systems. Herein, the MEMS micro-hotplate gas sensor based on in-situ grown CuO-In₂O₃ heterojunction nanocubes. This sensor enables precise, low-power temperature control through a MEMS micro-hotplate. Meanwhile, the in-situ growth technology facilitates a stable interfacial connection between the sensing material and the chip, which contributes to the exceptional consistency in device performance. Concurrently, the in-situ grown 10% CuO-In 2 O 3 heterojunction exhibits a uniform cubic structure, high specific surface area (81.2 m 2 /g), and large pore size (9.8 nm). This gas sensor exhibits high response toward CO (12.5 at 50 ppm), short response/recovery times (9/48 s), and excellent moisture resistance. More importantly, in batch-produced devices, the consistency error in sensor response is 2.02%, significantly enhancing the reliability and repeatability of device arrays. Density functional theory calculations revealed, at the atomic level, the selective adsorption and charge transfer mechanism of CO molecules at the CuO-In₂O₃ p-n heterojunction interface, elucidating the intrinsic cause of its enhanced sensitivity. Furthermore, we integrated this sensor with a Bluetooth module, successfully assembling a miniaturised wireless real-time monitoring device. This research establishes the material foundation for developing a new generation of non-invasive, portable bedside monitoring devices for neonatal jaundice. Download: Download high-res image (137KB) Download: Download full-size image