Microheater

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

Fabrication and Characterization of Surface-Micromachined Compact Microheater for Gas Sensing Applications

Abstract: A surface-micromachined compact microheater for gas sensing applications fabricated on a silicon substrate is presented. The heater was fabricated with a compatible CMOS process and its membrane was released using XeF2 isotropic silicon etching. The membrane had SiO2/SixNy/SiO2 layers (0.4/0.3/0.3 mum) in order to restrict the initial stress after the release, resulting in less than 2.5 mum height deviation from the membrane center to the anchor. The circular-type Pt (0.18 mum) heater proposed in this paper has a diameter of 110 mum and a width of 5 mum. It also shows a 4-probe measured heater resistance of 10.9 Omega, while that of the theoretical heater is 8.5 Omega. Also, to evaluate its thermal performance, the MEMS heater was characterized using an empirical parameter extraction method. As the total thermal loss coefficient of the heater (G,A) was modeled to 1.68e-5 W/K at ambient temperature (Tamb, 293 K) and the temperature coefficient of resistance at room temperature (TCRamb) was determined to be 0.00312 1/K, the heater temperature, as a total dissipated power function, was extracted to 700 K at 31 mW.

Interferometrically-coupled traveling-wave resonators for nonlinear optics applications

Abstract: A traveling-wave resonator structure with interferometric-coupling scheme is shown to have the capability of supporting both over-coupled and critically-coupled modes, simultaneously. This device is demonstrated in SOI with an integrated microheater to tune its coupling. The application of this device for nonlinear optics is discussed.

Electromigration Model for Platinum Hotplates

Abstract: Microheaters are frequently applied in the design of semiconductor metal oxide gas sensors in order to heat the sensing layer and induce the surface chemical reactions which promote molecular adsorption. One of the most common materials used for the microheater layer is platinum. In this manuscript, a model for electro-migration is developed and implemented to study vacancy dynamics and the thereby-induced stress in platinum-based microheaters for gas sensor applications. The model is then applied to study the impact of the individual components which contribute to vacancy transport, including electro-migration, thermo-migration, and stress-migration. We find that these structures have very high thermal gradients, making the impact of thermo-migration component higher than the electro-migration component in the early stages of vacancy transport, unlike in copper-based interconnects. Therefore, improving the temperature uniformity of the microheater design should lead to a longer operating time before failure.

Thermal modeling of a microheater in a microchannel chip

Abstract: Integration of microheaters in microfluidic systems has a wide range of applications such as sensing, actuating and biomedical devices. This study focused on the investigation of the thermal performance of a nickel microheater fabricated on a printed circuit board using a LIGA process. Both experimental and computational methods were used in conjunction with preliminary theoretical analysis. The microheater was tested both in air and water. The temperature distributions of the microheater were measured by an advanced thermography system. The numerical study was carried out using the multiphysics CFD package CFD-Ace+. The temperature of the microheater increased approximately linearly with the input power for the experimental conditions. The microheater heated up exponentially at the start of power supply. At a supply of 120mA electrical current, the microheater could heat up at a rate of around 90°C/s. During the cooling stage, the rate was much higher and could reach 800°C/s. When placed in the microchannel with air flow, the heater could heat the flow effectively without causing significant increase in the chip temperature. The CFD results were validated by comparing temperature distributions on the chip surface and on the heater surface. The validated CFD results allowed more detailed investigations of thermal and fluid flow within the microchannel and the whole chip.

A High-Efficiency Driver Circuit for a Gas-Sensor Microheater Based on a Switch-Mode DC-to-DC Converter

Abstract: Low power consumption is one of the critical factors for successful Internet of Things (IoT) applications. In such applications, gas sensors have become a main source of power consumption because energy conversion efficiency of the microheater is relative over a wide range of operating temperatures. To improve the energy-conversion efficiency of gas-sensor microheaters, this paper proposes integrated switch-mode DC-to-DC power converter technology which we compare with traditional driving methods such as pulse-width modulation and the linear mode. The results indicate that energy conversion efficiency with this proposed method remains over 90% from 150 °C to 400 °C when using a 3.0, 4.2 and 5.0 V power supply. Energy-conversion efficiency increases by 1-74% compared with results obtained using the traditional driving methods, and the sensing film still detects alcohol and toluene at 200 °C and 280 °C, respectively, with high energy conversion efficiency. These results show that the proposed method is useful and should be further developed to drive gas-sensor microheaters, and then integrated into the circuits of the complementary metal-oxide-semiconductor micro electro mechanical systems (CMOS-MEMS).