Microheater

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

Al Microheater and Ni Temperature Sensor Set based-on Photolithography with Closed-Loop Control

Abstract: This article proposes the development of a new low-cost microheater and temperature sensor set. It was developed based on Micro-Electro-Mechanical Systems (MEMS) which based on photolithography technique and lift-off technique. Thin film of aluminum was utilized as microheater and encompassed nickel temperature sensor inside in order to decrease response time of the desired temperature. To control the various temperatures correctly, closed-loop feedback control based on PI-controller was adapted into control circuit system. Microcontroller was implemented to control and observe the responses of temperature between 40°C and 120°C. Simulation and experimental results are also presented.

Direct writing of three-dimensional Cu-based thermal flow sensors using femtosecond laser-induced reduction of CuO nanoparticles

Abstract: We have demonstrated the fabrication of two types of thermal flow sensors with Cu-rich and Cu2O-rich microheaters using femtosecond laser-induced reduction of CuO nanoparticles. The microheaters in the shape of microbridge structures were formed to thermally isolate from the substrates by four layer-by-layer laminations of two-dimensional micropatterns. First, we evaluated the patterning properties such as dispensing coating conditions and degree of reduction for the selective fabrication of three-dimensional Cu-rich and Cu2O-rich microstructures. Then, a hot-film flow sensor with a Cu-rich microheater and a calorimetric flow sensor with a Cu2O-rich microheater were fabricated using their respective appropriate laser irradiation conditions. The hot-film sensor with the Cu-rich microbridge single heater enabled us to measure the flow rate in a wide range of 0–450 cc min−1. Although a large temperature dependence of the Cu2O-rich microbridge heaters caused a large error for the hot-film flow sensors with single heaters, they showed higher heat-resistance and generated heat with a lower drive power. The temperature coefficient of resistance of the Cu2O-rich microstructures had a semiconductor-like large absolute value and was less than −4.6 × 10−8 °C−1. The higher temperature sensitivity of the Cu2O-rich microstructures was useful for thermal detection. Based on these advantages, a calorimetric flow sensor composed of the Cu2O-rich microbridge single heater and two Cu2O-rich thermal detectors was proposed and fabricated. The calorimetric flow sensor was driven by a circuit for measuring the temperature difference. The Cu2O-rich flow sensor could detect bi-directional flow with a small output error.

Dynamic behaviors of approximately ellipsoidal microbubbles photothermally generated by a graphene oxide-microheater

Abstract: Thermal microbubbles generally grow directly from the heater and are spherical to minimize surface tension. We demonstrate a novel type of microbubble indirectly generated from a graphene oxide-microheater. Graphene oxide's photothermal properties allowed for efficient generation of a thermal gradient field on the microscale. A series of approximately ellipsoidal microbubbles were generated on the smooth microwire based on heterogeneous nucleation. Other dynamic behaviors induced by the microheater such as constant growth, directional transport and coalescence were also investigated experimentally and theoretically. The results are not only helpful for understanding the bubble dynamics but also useful for developing novel photothermal bubble-based devices.

Thermocapillary effects on low-g Pool Boiling from microheater arrays of various aspect ratio

Abstract: Pool boiling heat transfer measurements from heaters of varying aspect ratio were obtained in low-g (0.01 g ± 0.025 g) and high-g (1.7 g ± 0.5 g) using the KC-135 aircraft. The heater aspect ratio was varied by selectively powering 2×2, 2×4, 2×6, 2×8, and 2×10 arrays of heaters in a 10×10 heater array containing individual heaters 700×700 μm2 in size. Control circuitry was used to maintain a nominally isothermal boundary condition on the heater surface while the power dissipated by the heater was measured. Steady-state boiling data in low-g and high-g were obtained using FC-72 as the working fluid at two bulk fluid temperatures. At high wall superheats, boiling performance appears to decrease with an increase in aspect ratio. Strong thermocapillary convection was observed for a negligible gas concentration in the liquid. CHF was not observed for the heater used in this study indicating that CHF in low-g may be highly dependent on the surface characteristics of the heater in addition to the heater size.

Silicon nanowire-based nanoactuator

Abstract: A new class of nanoactuator based on the bimetal thermal effect of chromium-coated silicon nanowire has been demonstrated. The nanoactuator is fabricated by the localized synthesis process of silicon nanowires and coating them with a 5 nm-thick layer of chromium. Actuation occurs when the supporting microheater is heated locally by resistive joule heating which causes the nanowires to deflect due to the difference in the coefficient of thermal expansion (CTE) between chromium and silicon. Experimentally, the maximum measured deflection of a 3.66 /spl mu/m-long silicon nanowire is 1.52 /spl mu/m under a power input of 31.4 mW to the microheater.