• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.1783-1788
• /
• 2004

In the present paper, a micro flow sensor, which can be used at bio-delivery systems and micro heat pumps, is developed. For this, the micro flow sensor is integrated on a quartz wafer ($SiO_2$) and is manufactured by simple and convenient microfabrication processes. The micro flow sensor aims for measuring mass flow rates in the low range of about $0{\sim}20$ SCCM. The micro flow sensor is composed of temperature sensors, a heater, and a flow microchannel. The temperature sensors and the heater are manufactured by the sputtering processes in this study. In the microfabrication processes, stainless steel masks with different patterns are used to deposit alumel and chromel for temperature sensors and nichrome for the heater on the quartz wafer. The microchannel is made of Polydimethylsiloxane(PDMS) easily. A deposited quartz wafer is bonded to the PDMS microchannel by using the air plasma. Finally, we confirmed the good operation of the present micro flow sensor by measuring flow rate.

• 대한기계학회논문집B
• /
• 제32권7호
• /
• pp.542-548
• /
• 2008

A thermal mass air flow sensor (MAFS), which consists of a micro-heater and thermo-resistive sensors on the silicon-nitride ($Si_3N_4$) thin membrane structure, is micro-fabricated by MEMS processes. Two thermo-resistive temperature sensors are located at $100{\mu}m$ upstream and downstream from the micro-heater respectively. The thermal characteristics are measured to find the best measurement indicator. The micro-heater is operated under constant power condition, and four flow indicators are investigated. The normalized temperature indicator shows good physical meaning and is easy to use in practice. It is found that the configurations and heating power of thermal-resistive elements are the dominant factors to determine the range of the flow measurement in the MAFS with higher sensitivity and accuracy.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
• /
• pp.17-20
• /
• 2000

This paper describes on the fabrication and characteristics of hot-film type micro-flowsensors integrated with Pt-RTD's and micro-heaters on the Si substrate, in which MgO thin-films were used as medium layer in order to improve adhesion of Pt thin-films to $SiO_2$ layer, The MgO layer improved adhesion of Pt thin-films to $SiO_2$ layer without any chemical reactions to Pt thin-films under high annealing temperatures. In investigating output characteristics of the fabricated micro-flowsensors, the output voltages increased as gas flow rate and its conductivity increased due to increase of heat-loss from sensor to external. Output voltage was 82 mV at $N_2$ flow rate of 2000 seem/min, heating power of 1.2W.

• 한국정보통신학회논문지
• /
• 제9권3호
• /
• pp.595-600
• /
• 2005

마이크로 흐름센서는 반도체 집적기술을 이용할 수 있어, 소형으로 제작이 가능하며 빠른 응답특성을 가져 다양한 분야에 응용되고 있다. 본 연구에서는 넓은 흐름의 세기 영역에서 정밀한 감도를 가지는 2차원의 마이크로 흐름센서를 실리콘 기판위에 적충시켜 제작하였다. 흐름센서의 중앙에 하나의 히터와 양측에 온도를 검출할 수 있는 3쌍의 감지막을 가진 새로운 센서 구조를 제안하고, 온도 검출에 대한 성능평가를 위하여 시간영역에서의 유한차분법을 이용하여 공기흐름의 세기 변화에 따른 온도분포를 계산하였다. 계산결과를 통하여 실제 흐름센서의 동작을 정량적으로 분석하였다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 춘계종합학술대회
• /
• pp.363-366
• /
• 2005

마이크로 흐름센서는 종래의 반도체 집적회로 공정기술을 이용하여 소형으로 제작이 가능하며, 빠른 응답특성으로 다양한 응용이 기대되고 있다. 본 연구에서는 넓은 흐름의 세기 영역에서 정밀한 감도를 가지는 2차원 마이크로 흐름센서를 실리콘 기판위에 설계하였다. 흐름센서 중앙에 하나의 히터와 양측에 3쌍의 온도 감지막을 가진 새로운 구조를 제안하고, 제안된 구조의 성능평가를 위해 유한차분법을 이용하석 열운송방정식을 시간영역에서 해석하였다. 성능평가는 제안된 흐름센서 모델에 대하여 공기흐름의 세기 변화에 따른 온도분포를 계산함으로써 실제 흐름센서의 동작을 정량적으로 분석하였다.

• 대한기계학회논문집B
• /
• 제33권8호
• /
• pp.573-579
• /
• 2009

A thermal mass air flow sensor, which consists of a micro-heater and thermal sensors on the silicon-nitride thin membrane structure, is micro-fabricated by MEMS processes. Three thermo-resistive sensors, one for the measurement of microheater temperature, the others for the measurement of membrane temperature upstream and downstream of the micro-heater respectively, are used. The micro-heater is operated under the constant temperature difference mode via a real time controller, based on inlet air temperature. Two design models for microfabricated flow sensor are compared with experimental results and confirmed their applicabilities and limitations. The thermal characteristics are measured to find the best flow indicator. It is found that two normalized temperature indicators can be adopted with some advantages in practice. The flow sensor with this control mode can be adopted for wide capability of high speed and sensitivity in the very low and medium velocity ranges.

• Journal of Mechanical Science and Technology
• /
• 제20권4호
• /
• pp.554-560
• /
• 2006

This paper describes the demonstration of successful fabrication and initial characterization of micromachined pressure sensors and micromachined jets (microjets) fabricated for use in macro flow control and other applications. In this work, the microfabrication technology was investigated to create a micromachined fluidic control system with a goal of application in practical fluids problems, such as UAV (Unmanned Aerial Vehicle)-scale aerodynamic control. Approaches of this work include: (1) the development of suitable micromachined synthetic jets (microjets) as actuators, which obviate the need to physically extend micromachined structures into an external flow; and (2) a non-silicon alternative micromachining fabrication technology based on metallic substrates and lamination (in addition to traditional MEMS technologies) which will allow the realization of larger scale, more robust structures and larger array active areas for fluidic systems. As an initial study, an array of MEMS pressure sensors and an array of MEMS modulators for orifice-based control of microjets have been fabricated, and characterized. Both pressure sensors and modulators have been built using stainless steel as a substrate and a combination of lamination and traditional micromachining processes as fabrication technologies.

• 센서학회지
• /
• 제11권4호
• /
• pp.191-199
• /
• 2002

This paper presents the design concept, theoretical investigation, and fabrication of a six-degree of freedom (6-DOF) turbulent flow micro sensor utilizing the piezoresistive effect in silicon. Unlike other flow sensors, which typically measure just one component of wall shear stress, the proposed sensor can independently detect six components of force and moment on a test particle in a turbulent flow. By combining conventional and four-terminal piezoresistors in Si (111), and arranging them suitably on the sensing area, the total number of piezoresistors used in this sensing chip is only eighteen, much fewer than the forty eight piezoresistors of the prior art piezoresistive 6-DOF force sensor.

• 센서학회지
• /
• 제20권6호
• /
• pp.363-367
• /
• 2011

This paper proposes a highly-sensitive gas flow sensor with a simple structure. The sensor is composed of a micro-heater for heating the gas medium and a pair of temperature sensors for detecting temperature differences due to gas flow in a sealed chamber on one axis. Operation of the gas flow sensor depends on the transfer of heat through the air medium. The proposed gas flow sensor has the capability to measure gas flow rates <5 $cm^3$/min with a resolution of approximately 0.01 $cm^3$/min. Furthermore, this paper reports some additional experiment results, including the sensitivity of the proposed gas flow sensor as a function of operating current and the flow of different types of gas(oxygen, carbon dioxide, and nitrogen). The fabrication process of the proposed sensor is very simple, making it a good candidate for mass production.

• 센서학회지
• /
• 제9권5호
• /
• pp.334-340
• /
• 2000

본 논문에서는 패러데이의 전자기 유도 법칙을 응용한 마이크로 전자 유량 센서를 제작하였다. 마이크로전자 유량 센서는 열 발생이 없고 빠른 응답 속도를 가지고 있고 압력 손실이 없는 장점을 가지고 있다. 전도성 유체가 영구 자석 자장 내의 유로를 통과할 때, 유속에 비례하는 유도 기 전력이 발생하게 되는데, 발생된 기 전력은 유로 벽에 제작된 전극으로 검출된다. 마이크로 전자 유량 센서는 유로를 가지고 있는 두 장의 실리콘 웨이퍼 기판과 전극, 그리고 두 개의 영구 자석으로 구성되어 있다. 두 장의 실리콘 웨이퍼 기판을 이방성 식각 공정으로 유로를 제작하고, Cr/Au를 증착하여 전극을 제작한다. 제작된 마이크로 전자 유량 센서에 유량을 변화시킬 때, 발생되는 기 전력을 측정한다.