Robust Catalytic Gas Sensing Using a Silicon Carbide Microheater

Abstract

This paper reports the first use of a silicon carbide (SiC) microheater for stable low-power catalytic gas sensing. Catalytic combustion of hydrocarbon gases often requires high operating temperatures, which leads to instability in a previously developed low-power polycrystalline silicon (polysilicon) microheater. A silicon carbide microheater has been developed with low power consumption (20 mW to reach 500 °C) and improved stability, exhibiting an order of magnitude lower resistance drift than the polysilicon microheater after 100 hrs of continuous heating at 500 °C and during temperature increases up to 650 °C. When loaded with a high performance catalytic nanomaterial, the SiC microheater-based catalytic gas sensor exhibits fast response and recovery time (<1 s) and improved long-term stability for propane detection. The results show that a simple change of material from polysilicon to polySiC leads to a significant performance improvement of the microheater and the resulting sensor element.

In Situ Localized Growth of Ordered Metal Oxide Hollow Sphere Array on Microheater Platform for Sensitive, Ultra-Fast Gas Sensing

“…The fully fabricated sensor (shown schematically in Figure a) consists of an area-selected close-packed metal oxide hollow sphere array contacting Pt/Ti electrodes on a low power microheater platform (shown optically in Figure b), which consists of a polycrystalline 3C silicon carbide (polySiC) heater embedded in a suspended Si 3 N 4 membrane on a Si substrate. Full microheater fabrication and characterization details are provided in our prior report . The thermal isolation of the polySiC heater from the substrate reduces its heat loss, keeping power consumption low (13 mW to reach 500 °C, as shown in Figure S1 of Supporting Information).…”

“…Full microheater fabrication and characterization details are provided in our prior report. 45 The thermal isolation of the polySiC heater from the substrate reduces its heat loss, keeping power consumption low (13 mW to reach 500 °C, as shown in Figure S1 of Supporting Information).…”

“…The microheater platform consisted of a polycrystalline 3C silicon carbide heater embedded in a suspended Si 3 N 4 membrane on a Si substrate, and was fabricated using micromachining technology as detailed in our prior report . A monolayer of perfluorodecyltrichlorosilane was self-assembled on the microheater chip to reduce its surface energy, based on our previously developed procedure .…”

“…The microheater platform consisted of a polycrystalline 3C silicon carbide heater embedded in a suspended Si 3 N 4 membrane on a Si substrate, and was fabricated using micromachining technology as detailed in our prior report. 45 A monolayer of perfluorodecyltrichlorosilane was self-assembled on the microheater chip to reduce its surface energy, based on our previously developed procedure. 46 Briefly, the microheater chip was cleaned with deionized water, acetone, and isopropanol for 5 min each and UV/ozone for 20 min, followed by immersion in 0.1 vol % FDTS (Alfa Aesar) in isooctane in a low humidity chamber (<10% RH) for 60 min.…”