Microheater

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

Microheater and Process For Producing the Same

Abstract: To provide a microheater which gives a desired temperature and starts an exothermic reaction upon immediate contact with air and in which plural microheaters can be chained or incorporated in a packaging material. A microheater having a heat generating composition molded body made of a moldable heat generating composition containing surplus water as a connecting substance accommodated in an air-permeable accommodating bag, which is characterized in that the accommodating bag is made of a heat seal layer-containing substrate and a covering material and has an exothermic part as formed by laminating a heat generating composition molded body as molded on the substrate which is substantially planar and does not have a pocket, an accommodating division and an accommodating section, covering by the covering material and heat sealing the periphery of the heat generating composition molded body; that the moldable heat generating composition contains, as essential components, an iron powder, a carbon component, a reaction accelerator and water, has a content of water in the moldable heat generating composition of from 1 to 60%, does not contain a flocculant aid, a flocculant, an agglomeration aid, a dry binder, a dry binding agent, a dry binding material, a sticky raw material, a thickener and an excipient, contains surplus water so as to have a water mobility value of from 0.01 to 20, with the water in the heat generating composition not functioning as a barrier layer, and is capable of causing an exothermic reaction upon contact with air; that a volume of the heat generating composition molded body is from 0.1 to 30 cm 3 , and a ratio of a capacity of the exothermic part to the volume of the heat generating composition molded body is from 0.6 to 1.0; and that a maximum height of the exothermic part is from 0.1 to 10 mm.

Microheater Integrated Nanotube Array Gas Sensor for Parts-Per-Trillion Level Gas Detection and Single Sensor-Based Gas Discrimination.

Abstract: Real-time monitoring of health threatening gases for chemical safety and human health protection requires detection and discrimination of trace gases with proper gas sensors. In many applications, costly, bulky, and power-hungry devices, normally employing optical gas sensors and electrochemical gas sensors, are used for this purpose. Using a single miniature low-power semiconductor gas sensor to achieve this goal is hardly possible, mostly due to its selectivity issue. Herein, we report a dual-mode microheater integrated nanotube array gas sensor (MINA sensor). The MINA sensor can detect hydrogen, acetone, toluene, and formaldehyde with the lowest measured limits of detection (LODs) as 40 parts-per-trillion (ppt) and the theoretical LODs of ∼7 ppt, under the continuous heating (CH) mode, owing to the nanotubular architecture with large sensing area and excellent surface catalytic activity. Intriguingly, unlike the conventional electronic noses that use arrays of gas sensors for gas discrimination, we discovered that when driven by the pulse heating (PH) mode, a single MINA sensor possesses discrimination capability of multiple gases through a transient feature extraction method. These above features of our MINA sensors make them highly attractive for distributed low-power sensor networks and battery-powered mobile sensing systems for chemical/environmental safety and healthcare applications.

Optofluidic microvalve-on-a-chip with a surface plasmon-enhanced fiber optic microheater

Abstract: We present an optofluidic microvalve utilizing an embedded, surface plasmon-enhanced fiber optic microheater. The fiber optic microheater is formed by depositing a titanium thin film on the roughened end-face of a silica optical fiber that serves as a waveguide to deliver laser light to the titanium film. The nanoscale roughness at the titanium-silica interface enables strong light absorption enhancement in the titanium film through excitation of localized surface plasmons as well as facilitates bubble nucleation. Our experimental results show that due to the unique design of the fiber optic heater, the threshold laser power required to generate a bubble is greatly reduced and the bubble growth rate is significantly increased. By using the microvalve, stable vapor bubble generation in the microchannel is demonstrated, which does not require complex optical focusing and alignment. The generated vapor bubble is shown to successfully block a liquid flow channel with a size of 125 μm × 125 μm and a flow rate of ∼10 μl/min at ∼120 mW laser power.

Simple Fabrication and Characterization of a Platinum Microhotplate Based on Suspended Membrane Structure

Abstract: One of the key components of a microsensor is the Micro electromechanical system (MEMS) microheater. It has a wide range of applications such as gas sensors, pressure sensors, and so on. In this study, a platinum microhotplate based on suspended membrane structure is introduced. A simple microfabrication process is adopted to form the micromachined suspended microheater. Some integrated circuit processes such as E-beam evaporation of Pt and Au, oxidation, wet etching process, and photolithography process are used to fabricate the device. As the usage of deep-reactive ion etching and low-pressure chemical vapor deposition systems are avoided, the microfabrication process of the hotplate is accessible even in laboratories with limited equipment. In order to achieve uniform temperature distribution over the active heater area and to increase the robustness of the membrane, a thin silicon island was placed underneath the dielectric membrane. Thermal and thermomechanical behaviors of this structure obtained by finite element analysis show that the designed microhotplate is relatively strong. Experimental results show that power consumption and time constant are 50mW and 4.23ms, respectively, for the temperature variation from 30°C to 500°C in the fabricated microhotplates.