In-situ growth of Pt-doped NiO nanowalls for highly stable and selective MEMS acetone sensor

In-situ growth of NiO nanowalls on MEMS micro-hotplates secures Ohmic contact. • Pt doped into the NiO lattice intrinsically anchors oxygen vacancies. • The device achieves exceptional 60-day stability and 98% RH moisture resistance. • Rapid and ultraselective acetone sensing enables non-invasive diabetes screening. Non-invasive breath acetone analysis offers a promising approach for continuous diabetes monitoring. However, poor long-term stability and material-electrode interfacial drift in p-type metal oxide sensors remain key bottlenecks for their clinical translation. To address these challenges, a Micro-Electro-Mechanical-System (MEMS) acetone sensor was developed via the in-situ growth of Pt-doped NiO nanowalls on a micro-heater chip. Unlike conventional surface modification and physical coating methods, the intrinsic doping of Pt within the NiO lattice and its integration with the substrate address signal drift through a synergistic dual mechanism. Specifically, the in-situ growth minimizes contact resistance drift at the material-electrode interface. Simultaneously, intrinsic Pt lattice doping anchors the active sites, suppressing catalyst thermal agglomeration and preserving structural stability at the gas-solid interface. The optimized sensor exhibits a response of 10.3 to 100 ppm acetone at 200 °C (a 5.7-fold enhancement over pure NiO) and a response time of 37 s. Furthermore, the device demonstrates continuous stability over 60 days and steady-state reliability at the 1.8 ppm clinical diagnostic threshold. It also shows stable moisture resistance (up to 98% relative humidity), maintaining typical p-type characteristics without response reversal phenomena. Supported by competitive co-adsorption density functional theory (DFT) calculations, this moisture tolerance is attributed to a favorable adsorption energy that prioritizes acetone chemisorption over water molecules. Comprehensive characterizations and DFT models indicate that Pt doping triggers localized lattice distortions and charge compensation, increasing the surface oxygen vacancy concentration (35.2%). This theoretically broadens the hole accumulation layer (HAL) and facilitates single-molecule acetone adsorption (−1.12 eV), stabilizing the p-type conduction mechanism. This work provides a stable, drift-resistant acetone sensor capable of sub-ppm trace detection for non-invasive diabetes screening. Download: Download high-res image (204KB) Download: Download full-size image