Showing papers on "Microheater published in 1999"

Pyrotechnic actuator: a new generation of Si integrated actuator

Abstract: Mechanical micro actuators on silicon is playing a major role in the development of microsystems. In this context, many structures have been performed on electrostatic, piezo electric or pneumatic actuators. However, limitations remain when energetic micro actuations have to be created. We propose in this paper, a new original type of actuation based on the force generated by the combustion of an explosive. It consists of a micromachined silicon microheater (3 mm×3 mm×0.3 mm) on which a thin film of propellant (2 mm×2 mm×0.2 mm) is deposited. Its functioning principle is based on a hot gas emitted by the auto combustion of the propellant when its temperature reaches 300°C locally. In this paper, we present the results of a study (by modelling and experimental) of the ignition and combustion of a very small quantity of explosive onto a Si-micromachined microheater. We conclude by presenting two examples of applications showing the promising interest of this energetic actuator: the first application is the biomedical field. The second one, today is used for microspace craft attitude control.

Localized bonding with PSG or indium solder as intermediate layer

Abstract: The feasibility of "localized bonding" with PSG (phosphosilicate glass) or indium solder as the intermediate layer have been demonstrated. Both localized PSG-to-glass and indium-to-glass bonds are accomplished on a square bonding area (/spl sim/500/spl times/500 /spl mu/m/sup 2/) encompassed by 5 /spl mu/m wide microheaters made of phosphorus doped polysilicon. Either PSG or indium solder are deposited on top of the microheater and function as the intermediate bonding material. The separation of heating and bonding materials by the intermediate layer greatly improved the controllability of the bonding process. Moreover, the whole bonding process can be achieved in less than 2 minutes at atmospheric pressure and room temperature environment. This new bonding scheme has potential application for MEMS device packaging that requires low temperature processing at the wafer-level, but high temperature at the bonding interface.

Thermal analysis of fingerprint sensor having a microheater array

Abstract: For the purpose of properties security, in particular of information systems, demands for portable fingerprint sensors are increasing. We proposed a new type of fingerprint sensor having an arrayed microheater, and successfully fabricated one-dimensional array of sensor elements on a silicon wafer using micromachining technologies. Electric resistance of each heater element is measured as signals of temperature difference between elements that are in contact or non-contact with ridges of the fingerprints. In this paper, we analyzed thermal characteristics of our sensor device using computer modeling. Effects of the following parameters were investigated; cavity under heater, SiO/sub 2/ film between heater and sensor base, heater size, input power and pulse time duration applied to the heater, material properties contacting to sensor surface etc. We concluded that making cavities under the microheater elements and having SiO/sub 2/ film layer between heater element and sensor base both for the purpose of thermal insulation, is necessary to realize the performance of the proposed sensor system. From the simulation results, it was clarified that such a miniaturized heater element will work quite effective for detecting fingerprint patterns.

3D numerical simulation of novel SOI MOSFET based gas sensors

Abstract: This paper describes 3D numerical simulations of high temperature gas sensors based on SOI technology. A microheater is made of an SOI MOSFET device based on the self-heating. This new generation of integrated gas sensors has low power consumption (less than or equal to 25 mW) and uniform temperature distribution within the active area for a target temperature of 400 degrees C. The fabrication of the sensor is fully compatible with standard CMOS SOI technology The sensor has the enhanced thermal stability required at high operating temperatures, and improved device controllability due to MOS gate control.

Development of silicon microheaters for chemoresistive gas sensors

Abstract: We report on the design, fabrication, and characterization of a microheater module for chemoresistive, metal-oxide semiconductor gas sensors, consisting of a dielectric stacked membrane, micromachined from bulk silicon and with an embedded polysilicon resistor heater. Fabricated structures exhibit excellent heating efficiency, requiring only 30 mW to achieve a temperature of 500 C. Measured electrothermal characteristics are in good agreement with the outcomes of 3D numerical simulations.

Microheater as an alternative to lasers for in-vitro fertilization applications

Abstract: During the last decade various lasers have been applied to drilling of the micrometer-sized holes in the zona pellucida of oocytes for in-vitro fertilization applications. In this paper we describe an alternative approach to laser instrumentation based on microfabricated device capable of precise drilling of uniform holes in the zona pellucida of oocytes. This device consists of a thin (1 micrometer) film microheater built on the tip of glass capillary with a diameter varying between a few to a few tens of micrometers. Duration of the pulse of heat produced by this microheater determines the spatial confinement of the heat wave in the surrounding liquid medium. We have demonstrated that gradual microdrilling of the zona pellucida can be accomplished using a series of pulses with duration of about 300 microseconds when the microheater was held in contact with the zona pellucida. Pulse energy applied to 20 micrometer tip was about 4 (mu) J. In vitro development and hatching of 127 micromanipulated embryos was compared to 103 non-drilled control embryos. The technique was found to be highly efficient in creating round, uniform, well defined holes with a smooth wall surface, matching the size of the heating source. The architecture of the surrounding zona pellucida was unaffected by the drilling, as demonstrated by scanning electron microscopy. Micromanipulated embryos presented no signs of thermal damage under light microscopy. The rate of blastocyst formation and hatching was similar in the micromanipulated and control groups. Following further testing in animal models, this methodology may be used as a cost- effective alternative to laser-based instrumentation in clinical applications such as assisted hatching and embryo biopsy.

Flow sensor and its manufacture

Abstract: PROBLEM TO BE SOLVED: To reduce the heat loss of a bridge type micro-heater to a substrate in a flow sensor provided with the microheater. SOLUTION: The sensor chip 12 of a flow sensor 11 has a cavity section 15 formed through a silicon substrate 14 at the central part of the substrate 14. A thin film micro-heater 16 and a temperature sensor 17 are formed in the form of bridges laid across the cavity section 15. A supporting substrate 13 has a recessed section 21 at the position corresponding to the cavity section 15. When the sensor chip 12 is stuck to the supporting substrate 13, the distance Th from the micro-heater 16 to the substrate 13 becomes equal to the sum of the thickness of the silicon substrate 14 and the depth of the recessed section 21. Therefore, the sensitivity of detection of the flow sensor 11 can be improved, because the heat loss of the micro-heater 16 to the substrate 14 can be reduced by increasing the distance Th.