Area-Selective, In-Situ Growth of Pd-Modified ZnO Nanowires on MEMS Hydrogen Sensors

Abstract

Nanomaterials are widely utilized as sensing materials in semiconductor gas sensors. As sensor sizes continue to shrink, it becomes increasingly challenging to construct micro-scale sensing materials on a micro-sensor with good uniformity and stability. Therefore, in-situ growth with a desired pattern in the tiny sensing area of a microsensor is highly demanded. In this work, we combine area-selective seed layer formation and hydrothermal growth for the in-situ growth of ZnO nanowires (NWs) on Micro-electromechanical Systems (MEMS)-based micro-hotplate gas sensors. The results show that the ZnO NWs are densely grown in the sensing area. With Pd nano-particles’ modification of the ZnO NWs, the sensor is used for hydrogen (H2) detection. The sensors with Pd-ZnO NWs show good repeatability as well as a reversible and uniform response to 2.5 ppm–200 ppm H2. Our approach offers a technical route for designing various kinds of gas sensors.

Morphology control technique of ZnO by hydroxide ion supply rate and its effect on the ppt‐level gas sensors

“…[16][17][18][19] In addition, ZnO has been synthesized in various morphologies, and its gas-sensing results according to shape have been reported. [20][21][22][23] ZnO nanobelt with atomic steps has been reported by our group, and this material can detect until the ppt level of acetone without any novel metal catalyst. 24 It is due to that the atomic step structures as atomic defects at the surface could generate pre-adsorbed oxygen species with lower energy as compared with a pristine surface.…”

“…ZnO, a typical n‐type metal oxide, was applied in various kinds of applications 16–19 . In addition, ZnO has been synthesized in various morphologies, and its gas‐sensing results according to shape have been reported 20–23 . ZnO nanobelt with atomic steps has been reported by our group, and this material can detect until the ppt level of acetone without any novel metal catalyst 24 .…”

High-Throughput Color Imaging Hg2+ Sensing via Amalgamation-Mediated Shape Transition of Concave Cube Au Nanoparticles

“…Single-particle imaging provides higher sensitivity toward analytes compared to traditional bulk measures because each nanoparticle is considered to be the output of a separate signal response and tiny variations occurring on single-particles can be monitored with DFM [ 15 , 22 ]. Under the optimal conditions, we imaged the color variation of concave cube Au nanoparticles with increasing Hg 2+ concentrations in the range of 0–4000 nM and the (G+B)/R ratio Gaussian fitting was obtained to quantify Hg 2+ concentration (Over 500 particles for statistics).…”

“…Lately, the emerging single-particle detection (SPD) method with dark-field microscopy (DFM) has been widely concerned owing to its high signal-to-noise ratio, good spatiotemporal resolution, and ultralow sample consumption, providing more possibilities for the exploration of special chemical reactions [ 15 ]. In addition, single-particle imaging detection provides excellent sensitivity toward analytes and explains the unknown mechanism because each nanoparticle is considered to be the output of a separate signal response and tiny variations occurring on single-particles can be monitored with DFM [ 16 , 17 , 18 ].…”

Highly Sensitive MEMS Sensor Using Bimetallic Pd–Ag Nanoparticles as Catalyst for Acetylene Detection

“…Recently, Lu et al reported another Ti-based composite oxide sensing electrode, which has a detection limit of 500 ppb for acetylene [ 29 ]. For on-site detection of trace gases, such as acetylene, miniature gas sensors with high sensing performance and low power consumption have attracted much attention [ 31 , 32 , 33 , 34 , 35 , 36 ].…”