Integrated microsensor for precise, real-time measurement of junction temperature of surface-mounted light-emitting diode

Choi, Hyunjin,Choi, Woohyuk,Lim, Jiseok,Choi, Jungwook Elsevier 2019 Sensors and actuators. A Physical Vol.298 No.-

<P><B>Abstract</B></P> <P>Light-emitting diodes (LEDs) are widely used in many industrial applications owing to their high performance and efficiency compared with conventional lighting systems. However, a considerable amount of input power is inevitably dissipated into heat at the LED junction, which can degrade the performance and reliability of the LED; thus, it is important to monitor the change in the junction temperature of the LED. In this study, we present a micro-temperature sensor-integrated surface-mounted device (SMD) for accurate and real-time measurement of the junction temperature of an LED. The LED is mounted on a microfabricated Pt sensor in a similar way to the typical SMD assembly. The heat generated at the LED junction is conductively transferred to the microsensor, increasing the temperature and changing its electrical resistance. In contrast to the conventional techniques for thermal characterization of LEDs, the integrated microsensor provides real-time information on the junction temperature with high precision, reproducibility, and simplicity. Additionally, the temperature of the solder, which is not easily accessible but is closely related to the reliability of the LED, can be estimated by analyzing the thermal resistance of the LED package. Experimental and numerical results indicate a linear correlation (R<SUP>2</SUP> = 0.988) between the junction and sensor temperatures, which is practically useful for the thermal management of the miniaturized SMD-LED.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Methodology for measuring LED junction temperature is proposed. </LI> <LI> Pt micro-temperature sensor-integrated SMD-LED is designed and fabricated for real-time measurement of junction temperature. </LI> <LI> Highly linear correlation of the temperature between the microsensor and the junction is experimentally found. </LI> <LI> Analysis of structure function, thermal resistance, and numerical calculation of SMD-LED validates measurement accuracy of Pt microsensor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Buckling and vibration of porous sandwich microactuator-microsensor with three-phase carbon nanotubes/fiber/polymer piezoelectric polymeric nanocomposite face sheets

Ali Ghorbanpour Arani,Borhan Rousta Navi,Mehdi Mohammadimehr 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.6

In this research, the buckling and free vibration of three-phase carbon nanotubes/ fiber/ polymer piezoelectric nanocomposite face sheet sandwich microbeam with microsensor and micro-actuator surrounded in elastic foundation based on modified couple stress theory (MCST) is investigated. Three types of porous materials are considered for sandwich core. Higher order (Reddy) and sinusoidal shear deformation beam theories are employed for the displacement fields. Sinusoidal surface stress effects are extracted for sinusoidal shear deformation beam theory. The equations of motion are derived by Hamilton’s principle and then the natural frequency and critical buckling load are obtained by Navier’s type solution. The determined results are in good agreement with other literatures. The detailed numerical investigation for various parameters is performed for this microsensor-microactuator. The results reveal that the microsensor-microactuator enhanced by increasing of Skempton coefficient, carbon nanotubes diameter length to thickness ratio, small scale factor, elastic foundation, surface stress constants and reduction in porous coefficient, micro-actuator voltage and CNT weight fraction. The valuable results can be expedient for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

Development and Application of a Novel Miniature in situ Microprofiler (NAFRI BelpI)

이재성,김은수,강성현,윤석현,조진형,박경수,강동진 한국해양과학기술원 2012 Ocean science journal Vol.47 No.4

We have developed a novel miniature in situ microprofiler (NAFRI BelpI) for coastal and deep-sea studies. The BelpI can carry up to three oxygen microsensors, and it allows for simultaneous replicate measurements in a relatively small area. All functions can be controlled and programmed via a small magnetic bar and three reed switches; this feature facilitates the initial setup both onboard and underwater. The large LCD window shows basic information such as the movement intervals of the linear stage, number of replicate measurements, waiting time between measurements, and the pA from the microsensors. From high-resolution vertical profiles of oxygen in coastal sediment measured using the microsensors, the diffusivity boundary layer thicknesses was determined to be in the range 0.30 - 0.35 mm. In addition, the time-series measurement of oxygen profiles in permeable sandy sediment showed advective transport of oxygen into pore water by tidal agitation. Two examples of in situ measurement using a BelpI suggest that it can be widely applied to the study of the sediment-water interface.

Flow channel과 microsensor를 내장한 전해질 측정용 소형 카트리지 제작

이영철,조병욱,김창수,고광락,손병기 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

A cartridge for FET type sensors was designed and fabricated by using micromachining techniques such as silicon etching and bonding techniques. The photosensitive polymer(THB 30) is used to define an uniform micropool and to encapsulate the sensor surface. A REFET is fabricated to replace the conventional reference electrode using photosensitive polymer(OMR 83). The fabricated cartridge includes four electrolyte sensors (H^(+), K^(+), Ca^(2+), Na^(+)), and the dead volume of intergrated flow channel is about 8μl.

Heterogeneity of Skin Oxygen Density Distribution: Relation to Location of Acupuncture Points

Youngmi Lee,Gwanyung Lee,Sarah S. Park,Angela Jang,Gil-Ja Jhon 사단법인약침학회 2009 Journal of Acupuncture & Meridian Studies Vol.2 No.4

To investigate possible functions of acupuncture, oxygen (O2) levels were measured at two different acupuncture points (APs) [Hegu and Laogong] and at the corresponding non-APs (3−5 cm away from the APs) in real time using a high sensitive electrochemical O2 microsensor. The sensor had a small planar sensing platinum disk (diameter = 25 μm) and therefore was able to monitor the O2 levels at the localized APs. Significantly higher O2 levels (p < 0.05) were observed at both APs (n = 5, without exceptions) in comparison with the non-APs. Sufficient sensor sensitivity to distinguish the O2 level differences between APs and non-APs was achieved. This research provides useful information on possible functions of APs and meridians. To investigate possible functions of acupuncture, oxygen (O2) levels were measured at two different acupuncture points (APs) [Hegu and Laogong] and at the corresponding non-APs (3−5 cm away from the APs) in real time using a high sensitive electrochemical O2 microsensor. The sensor had a small planar sensing platinum disk (diameter = 25 μm) and therefore was able to monitor the O2 levels at the localized APs. Significantly higher O2 levels (p < 0.05) were observed at both APs (n = 5, without exceptions) in comparison with the non-APs. Sufficient sensor sensitivity to distinguish the O2 level differences between APs and non-APs was achieved. This research provides useful information on possible functions of APs and meridians.

산소 미세전극을 이용한 강화군과 인천 북항 조간대 갯벌의 순광합성률 측정

황청연,조병철,Hwang, Chung-Yeon,Cho, Byung-Cheol 한국해양학회 2005 바다 Vol.10 No.1

갯벌에서 순 광합성률의 시기적 변화를 살펴보기 위해 강화군의 서남단과 남단에 각각 위치한 장화리와 동막리의 조간대 갯벌과, 유기물 함량이 상대적으로 높은 인천 북항 조간대 갯벌을 대상으로 2003년 12월부터 2004년 6월까지 4회에 걸쳐 산소 미세전극을 이용하여 퇴적물 내 산소 농도의 수직 분포를 측정하였다. 조사 기간 동안 장화리와 동막리 갯벌에서 산소의 퇴적물 투과 깊이는 12월에 가장 컸으며(평균 $4.0{\sim}4.1\;mm)$),이후 조사에서는 각각 평균 $2.2{\sim}2.8\;mm$와 $1.6{\sim}l.8\;mm$의 값으로 작아지는 경향을 보였다. 흥미롭게도 인천 북항 갯벌의 산소 투과 깊이는 시기에 관계없이 $0.8{\pm}0.3\;mm$(평균${\pm}ISD$)의 작은 값을 나타냈다. 순 광합성률은 동막리 갯벌에서 3월에 최대값$(11.1{\pm}2.8\;mmol\;O_2\;m^{-2}\;h^{-1})$을 보였으며 장화리와 인천 북항 갯벌에서는 5월에 각각 $6.1{\pm}4.1\;mmol\;O_2\;m^{-2}\;h^{-1}$와 $6.4{\pm}1.4\;mmol\;O_2\;m^{-2}\;h^{-1}$의 최대값을 보였다. 순 광합성률이 최대값을 보인 시기에, 퇴적물 내 공극수의 용존 산소 농도의 최대값은 깊이 $0.1{\sim}0.5\;mm$구간에서 관찰되었으며, 대기로 포화된 표층 해수의 용존 산소 농도에 비해 평균적으로 $1.8{\sim}3.2$배 높았다. 6월 조사 당일에 현장의 광량(400 ${\mu}Einst\;m^{-2}\;s^{-1}$)이 다른 조사 시기에 비해 낮았지만, 이를 감안하더라도 세 지역의 순 광합성률은 크게 감소하여 $0.2\;mmol\;O_2\;m^{-2}\;h^{-1}$이하의 값을 나타냈다. 결론적으로, 순 광합성률의 시기적인 변화 양상은 연구 지역에 따라 다소 차이가 있었지만, 대개 봄철에 표층 0.5mm이내에 분포하는 저서 일차 생산자에 의해 광합성이 가장 활발하게 일어나는 것으로 나타났다. 본 연구는 산소 미세전극을 이용한 갯벌의 광합성 연구에 대한 국내에서의 첫 보고이며, 이 기술은 갯벌의 일차 생산력이나 표층 퇴적물의 산소 소모율 등을 추정하는데 유용하게 활용될 수 있을 것으로 여겨진다. To find out temporal variations of net photosynthetic rate (NPR) of intertidal flats, we measured oxygen microprofiles in sediments with oxygen microsensors 4 times from December 2003 to June 2004. The study areas were the intertidial flats in Janghwa-ri and Dongmak-ri, located on the southwestern and the southern parts of Ganghwa-gun, respectively, and in Incheon North Harbor where the content of organic matter was relatively high. During the investigation, oxygen penetration depths in the tidal flats of Janghwa-ri and Dongmak-ri were high in December (mean values of 4.0-4.1 mm). Thereafter, the oxygen penetration depths declined to mean values of 2.2-2.8 mm and 1.6-1.8 mm in the two tidal flats. Interestingly, the oxygen penetration depths in the Incheon North Harbor tidal flat showed a lower range $(0.8{\pm}0.3\;mm;\;mean{\pm}1SD)$ over the period. The maximum NPR in the Dongmak-ri tidal flat was found in March $(11.1{\pm}2.8\;mmol\;O_2\;m^{-2}\;h^{-1})$, and those In Janghwa-ri $(6.1{\pm}4.1\;mmol\;O_2\;m^{-2}\;h^{-1})$ and Incheon North Harbor $(6.4{\pm}1.4\;mmol\;O_2\;m^{-2}\;h^{-1})$ were observed in May. During the period when NPR was most active, the highest oxygen concentration was found at 0.1-0.5 mm depth below the surface sediment, and was on average 1.8-3.2 times higher than the air-saturated oxygen concentration in the overlying seawater. Although we took into account of low in situ light intensity $(400{\mu}Einst\;m^{-2}\;s^{-1})$ during the investigation in June, NPR in the 3 study areas decreased significantly to less than $0.2\;mmol\;O_2\;m^{-2}\;h^{-1})$. Thus, temporal variations of NPR were somewhat different among the tidal flats. Generally, benthic primary producers inhabiting in the uppermost 0.5 mm of the sediment showed a peak photosynthetic activity in the study areas in spring. This is the first domestic report on photosynthetic rates of benthic microflora in the tidal flats with oxygen microsensors, and the use of the microsensor can be widely applied to measurements of benthic primary production of a tidal flat and the oxygen consumption rate of surficial sediments.

Simple Fabrication of Amperometric Nitric Oxide Microsensors Based on Electropolymerized Membrane Films

Ho Shim, Jun,Do, Hyunkyung,Lee, Youngmi WILEY-VCH Verlag 2010 Electroanalysis Vol.22 No.3

<P>Demand for highly sensitive, selective, and practically reliable sensors which could be easily fabricated is increasing for various applications in biological and biomedical systems. Thus, here we present a novel and simple amperometric NO microsensor based on electropolymerized polymeric films. The sensor consists of a platinized Pt disk anode (25-μm diameter) which surface is modified with electropolymerized polymer films and a Ag/AgCl wire cathode coiled around the anode. Three different electropolymerized films prepared from m-phenylenediamine (m-PD), 2,3-diaminonaphthalene (2,3-DAN), and 5-amino-1-naphthol (5A1N) are compared in terms of their permselectivity for NO over major biological interferents such as anionic nitrite, ascorbic acid, uric acid; neutral acetaminophen; and cationic dopamine. Poly-5A1N film layer among the three different polymers shows the best anti-interference characteristics for all the electroactive interferents examined. Indeed, single polymer film of electropolymerized 5A1N without any additional modification as a NO selective membrane is confirmed to be sufficient to reject anionic, neutral, as well as cationic interferents while allowing relatively high permeation of NO through it. Other analytical performance of the NO microsensor fabricated with poly-5A1N is evaluated: reliable linear dynamic range (a few tens nM to μM); sensitivity of 122.0±2.5 pA/μM; detection limit of <5.8 nM (S/N=3); response time, t<SUB>90%</SUB><5 s, which are excellent when considering the small sensor size. Another sensor design which has both an anode (poly-5A1N modified platinized Pt) and a cathode (Ag/AgCl disk) embedded in a single sensor body is also presented.</P>

Selective Electro – Thermal Growth of Zinc Oxide Nanowire on Photolithographically Patterned Electrode for Microsensor Applications

서영덕,고승환,홍석준,김근호,황광일,최준호,홍원화,여준엽 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.2

Hydrothermal growth of zinc oxide (ZnO) nanowire (NW) enables a facile synthesis of versatile 1D nanostructure, but the conventional bulk heating procedure is assessed to be unsuitable for microsensor application in terms of selectivity and power consumption. In this study, we introduce selective electro-thermal growth of ZnO NW on photolithographically patterned electrode in the liquid environment. By applying constant current to the targeted electrode, densely packed ZnO NWs are successfully synthesized only at the desired electrode with very small power consumption. It is also confirmed that the electro - thermally grown ZnO NW network connecting two distinct electrode can be utilized as photosensitive channel, proving that this process as well as the resultant ZnO NW has a high potential for microsensor applications.

Sediment Oxygen Consumption in Semi-Closed Korean Coastal Bays during Summer

이재성,김성길,김성수,안순모,김영태,최옥인 한국해양과학기술원 2009 Ocean science journal Vol.44 No.3

We used an oxygen microsensor for high-resolution measurements of pore water oxygen concentration in semiclosed coastal bays of the South Sea of Korea during summer. The oxygen penetration depths ranged from 0.60 to 3.65 mm. Oxygen consumption rates were estimated to be 9.1 to 59 mmol m–2 d–1 (average: 22.8 mmol m–2 d–1). At the sediment–water interface, the oxidation rates of organic carbon were estimated to be 84–545 mg C m–2 d–1 (average: 211 mg C m–2 d–1). Approximately 38% (~211 mg C m–2 d–1) of pelagic primary production was regenerated in the surface sediment, indicating the tight benthic–pelagic coupling in the coastal sea of the South Sea of Korea. We used an oxygen microsensor for high-resolution measurements of pore water oxygen concentration in semiclosed coastal bays of the South Sea of Korea during summer. The oxygen penetration depths ranged from 0.60 to 3.65 mm. Oxygen consumption rates were estimated to be 9.1 to 59 mmol m–2 d–1 (average: 22.8 mmol m–2 d–1). At the sediment–water interface, the oxidation rates of organic carbon were estimated to be 84–545 mg C m–2 d–1 (average: 211 mg C m–2 d–1). Approximately 38% (~211 mg C m–2 d–1) of pelagic primary production was regenerated in the surface sediment, indicating the tight benthic–pelagic coupling in the coastal sea of the South Sea of Korea.

Timeout-based Information Forwarding Protocol for Wireless Sensor Networks

Jeong, Wootae,Nof, Shimon Y. Taylor & Francis 2007 INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWOR Vol.3 No.4

<P> Recent wireless microsensor network protocols provide more flexible leverage to the applications with dynamically changing topology, but they should be designed to overcome energy constraints, the bandwidth limit, and system latency. Thus, microsensor network protocols should be effective both in energy and in latency. In addition, they should be evaluated through designated tools at each level of networking characteristics. This paper proposes a new Timeout-based Information Forwarding (TIF) protocol for wireless sensor networks. It uses a relatively simple logic to forward the data packet with multi-hop fashion to reduce the overall network energy consumption. The TIF protocol has been implemented into a network evaluation tool, called TIE/MEMS, and provides a design strategy for distributed wireless sensor network systems needed for various emerging applications. The simulated results show that the TIF protocol has low energy consumption and provides design guidelines between energy consumption and latency according to the number of hops by adjusting weight values in the timeout function.</P>