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Microheater
About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.
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2 citations
TL;DR: In this article, phase sensitive measurements were applied to a CMOS compatible micromachined pressure sensor consisting a polysilicon sense line, 760 microns long, on an oxide microbridge separated by 6 microns on each horizontal side from similar poly-silicon heaters.
Abstract: Phase sensitive AC measurement techniques are particularly applicable to micromachined sensors detecting temperature changes at a sensor caused by a microheater. The small mass produces rapid thermal response to AC signals which are easily detectable with lock-in amplifiers. Phase sensitive measurements were applied to a CMOS compatible micromachined pressure sensor consisting a polysilicon sense line, 760 microns long, on an oxide microbridge separated by 6 microns on each horizontal side from similar polysilicon heaters, all over a micromachined cavity. Sinusoidal heater signals at 32 Hz induced temperature caused sense line resistance changes at 64 Hz. The lock-in detected this as a first harmonic sense resistor voltage from a DC constant sense current. By observing the first harmonic the lock-in rejects all AC coupling of noise by capacitance or inductance, by measuring only those signals at the 64 Hz frequency and with a fixed phase relationship to the heater driver signals. This sensor produces large signals near atmospheric pressure, declining to 7 (mu) V below 0.1 mTorr. Phase measurements between 760 and 100 Torr where the air's thermal conductivity changes little, combined with amplitude changes at low pressure generate a pressure measurement accurate at 5 percent from 760 Torr to 10 mTorr, sensing of induced temperature changes of 0.001 degree C.
2 citations
09 Jan 2022
TL;DR: In this article , ZSM-5 zeolites are used as catalysts to improve the sensing performance of ZnO-based sensor to the typical Freon refrigerant of R134a.
Abstract: As a typical kind of greenhouse gas, Freon refrigerant significantly harms the environment and should be detected at low concentrations. In this paper, ZSM-5 zeolites are used as catalysts to improve the sensing performance of ZnO-based sensor to the typical Freon refrigerant of R134a. To quantitatively evaluate the activities of the ZSM-5 catalysts, resonant microcantilever integrated with a microheater is designed and fabricated. The frequency-shift brought by the heating induced desorption of probe molecules is used to represent the activities of the ZSM-5 catalysts. According to the measured frequency-shifts, the activities of the four candidate zeolites can be optimized without the trial-and-error tests. The gas sensing results well verify the evaluation results, which indicates that the resonant microcantilever can be used to quantitatively characterize the activities of catalysts for gas sensor usages.
2 citations
TL;DR: In this paper, the authors proposed the design of Microhotplate and integrate on a suspended membrane and its Electro- Thermal simulation is reported using COMSOL Multiphysics 4.2.
Abstract: Sensitivity and Selectivity are two key parameters in the MEMS based sensor applications. Micro hotplate along with the sensing layer does the sensing applications. Microhotplate is used increase the temperature of the sensing layer to make it more suitable of finding the gas analyte. The work proposes the design of Microhotplate and integrate on a suspended membrane and its Electro – Thermal simulation is reported using COMSOL Multiphysics 4.2. The integration of Polyimide Microheater on a Micromachined substrate provides temperature uniformity across the active area of the device for heating the sensing layer to low temperature and also it makes the sensing layer more sensitive and selective. The optimum temperature of operation of Microheater was found to be 250°C and the power consumption at this operating temperature range was found to be 70mW, when a 5V bias is applied across the resistive beam of the Microheater. Unlike the conventional materials that were used for the design such as SiO2/Si3N4 composite layer the polymer materials shows enhanced performance.
2 citations
Patent•
24 Feb 1998
TL;DR: In this article, the authors propose to widen the scope of free selection of an ink by structuring an actuator means in such a way that the energy for discharging ink droplets by deformation due to thermal expansion is generated.
Abstract: PROBLEM TO BE SOLVED: To widen the scope of free selection of an ink by structuring an actuator means in such a way that the energy for discharging ink droplets by deformation due to thermal expansion is generated, in a device for discharging ink droplets by pressurizing the ink of an ink liquid chamber with the help of the actuator means. SOLUTION: Electricity is fed to a microheater 5 of an actuator means 6 through electrode parts 7, 8 to heat he microheater 5 at about 200°C. Consequently, a mechanical shape change occurs based on the difference in a coefficient of heat expansion between an Ni-Cr coating film 4 and an SiO 2 coating film 2 which form the microheater 5. That is, the actuator means 6 is deformed in such a manner that it protrudes to the higher value side of the coefficient of heat expansion (the microheater 5 side). As a result, an ink in an ink liquid chamber 10 is pressurized to discharge ink droplets 16 from a nozzle 13. When this kind of actuator means 6 is used, it is possible to control the amount of the ink droplets 16 to an optimal level by controlling the degree (temperature) of heating and therefore, solve the problem of kogation (scorching). COPYRIGHT: (C)1999,JPO
2 citations