Microheater

About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.

Boosting Electrical Response toward Trace Volatile Organic Compounds Molecules via Pulsed Temperature Modulation of Pt Anchored WO3 Chemiresistor

Abstract: Insufficient limit of detection (LoD) toward volatile organic compounds (VOCs) hinders the promising applications of metal oxide chemiresistors in emerging air quality monitoring and/or breath analysis. There is an inherent limitation of widely adopted strategies of creating sensitive chemiresistors then operating at the optimized temperature via a continuous heating (CH) mode. Herein, a strategy combining Pt single atoms anchoring (chemical sensitization) with pulsed temperature modulation (PTM, physical sensitization) is proposed. Apart from generating abundant surface asymmetric oxygen vacancy (Pt‐VO‐W) active sites at pulsed high temperature (HT) stage, inward diffusion of trace target VOCs across the sensing layer at pulsed low temperature stage (driven by PTM induced concentration gradient), can greatly enhance the charge interaction probability between the generated surface active species and the surrounding VOCs, and thus offers a novel avenue on addressing the bottleneck issue of low LoD by PTM. Triggered by HT of 300 °C, the responses of Pt anchored WO3 chemiresistor to 1 ppm trimethylamine (TMA) and xylene can be drastically boosted from 1.9 (CH) to 6541.5 (PTM) and 1.5 (CH) to 1001.1 (PTM), respectively. And ultra‐low theoretic LoD of 0.78 ppt (TMA) and 0.18 ppt (xylene) are successfully achieved, respectively.

Formation of 10-μm-level patterned organic thin film using microthermal evaporation

Abstract: This article reports the fabrication of 10-μm-level stripe patterns on an organic layer using microthermal evaporation. During this process, an organic layer is coated on a glass substrate with a bridge-type microheater array, and then selectively evaporated and deposited to form a fine pattern onto another glass substrate, separated by a micron-scale gap from the microheater array. Using a unique numerical model for microthermal evaporation, thickness profiles of the pattern were calculated and matched to experimental data. Furthermore, high optical qualities of the transferred luminescent pattern layer were confirmed using microphotoluminescence spectroscopy. This microthermal evaporation method confirms the feasibility of fabricating fine organic patterns with scalability to larger sizes.

Wafer-level fabrication of low power consumption integrated alcohol microsensor

Abstract: An integrated alcohol microgas sensor was designed and fabricated based on TiO 2 /SnO 2 nanocomposites acting as a sensing layer and microheater providing working temperature. The stacked TiO 2 /SnO 2 nanocomposites were prepared by magnetron sputtering. A unique suspended membrane consisting of Si 3 N 4 /SiO 2 /Si 3 N 4 /SiO 2 four layers was prepared by different methods, respectively, and applied in microheater to support the electrodes and sensing layer for reducing power consumption. The fabrication process tackled the difficulty that the sensing layer preparation is incompatible with microelectromechanical systems micromachining technology and realised the mass production of the wafer-level sensor chips with good consistency. The microalcohol sensors showed excellent response characteristics for alcohol (50-600 ppm) detection at low power consumption (39 mW).

Batch fabrication of micro preconcentrator with thin film microheater using Tollen's reaction

Abstract: A batch fabrication with simple micromachined process based on one photomask and the microfluidic laminar flow patterning technique is developed for a novel micropreconcentrator (μPCT) used in a micro gas chromatograph (μGC). Silver deposition using Tollens' reactions in microfludic channels provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (> 200 μm). An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microchannel. The μPCT can be heated to >300°C rapidly by applying a constant electrical power of ~5 W with a heating rate of 60°C/s. Four volatile organic compounds (VOCs), acetone, benzene, toluene, and xylene, are collected through the proposed novel μPCTs and separated successfully using a 17-m-long gas chromatography (GC) column. Compared with our previous work, the more uniform temperature distribution, more efficient heating rate and smaller peak widths at half height (PWHH) are obtained.

Simulation study of power loss components in a microheater

Abstract: Microheaters have been employed in wide variety of applications. While designing microheaters for any specific application, it is necessary to identify the individual loss components because the total power consumption depends primarily on the significant part of loss mechanism. Proper design of a microheater that can perform efficiently over the entire operating region is of utmost importance. This paper identifies the individual components of heat loss mechanisms and their region of dominance with respect to the temperature spectrum. The convection loss mechanism has as much as 30% contribution of total heat losses. The nitride layer, which is used for providing the electrical insulation has resulted in an additional 56:6% of power demand for a heater operating at 620K. This is a significant power intake for any battery operated, hand held devices for a continuous monitoring applications such as gas sensors or air quality monitors.