The use of thermochromic liquid crystals in research applications, thermal mapping and non-destructive testing

Parsley, M.

doi:10.1109/stherm.1991.152912

Cited by 15 publications

(15 citation statements)

References 33 publications

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“…The wavelength of maximum reflectivity decreases with increasing temperature within a range specific to the chemical composition, which can be customized. After they have been encapsulated by a nonreactive polymer, beads of TLC's can serve as long-lasting coatings for surface thermometry or as neutrally buoyant temperature and/or velocity markers in a fluid [6], [7], [9]- [11].…”

Section: Thermochromic Liquid Crystalsmentioning

confidence: 99%

“…The PID controller converts the thermistor resistance value to temperature. tical properties that are strongly sensitive to temperature within ranges specific to their chemical composition [6], [7]. Within the sensitivity range of a given TLC, the wavelengthdependent reflectivity varies strongly with temperature and induces a strong temperature dependence of the apparent color.…”

mentioning

confidence: 99%

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Transient liquid crystal thermometry of microfabricated PCR vessel arrays

Chaudhari

Woudenberg²,

Albin³

et al. 1998

J. Microelectromech. Syst.

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Abstract-Polymerase chain reaction (PCR) using micromachined structures promises improved temperature uniformity and cycling time together with decreased reagent and sample volumes. Thermal design of these structures will benefit from measurements of the temperature distribution in the reacting liquid. We report measurements of temperature uniformity and time constant in a microfabricated 18-vessel array using encapsulated liquid crystals suspended in the liquid. Separate sets of crystals are used to image temporal and spatial temperature variations near the processing thresholds of 55 C and 95 C with a resolution of 0.1 C. While the thermometry technique developed here is particularly useful for characterizing microfabricated PCR systems, it can also aid with the thermal design of a broad variety of microfluidic devices. [330]

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Section: Thermochromic Liquid Crystalsmentioning

confidence: 99%

mentioning

confidence: 99%

Transient liquid crystal thermometry of microfabricated PCR vessel arrays

Chaudhari

Woudenberg²,

Albin³

et al. 1998

J. Microelectromech. Syst.

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show abstract

“…Various equipment has been used for the physical contact measurement, including thermocouples, thermistors, scanning thermal probes, and multiple contact or blanket coatings such as liquid crystals and thermographic phosphors [59][60][61][62][63][64][65]. The aforementioned equipment relies on the transfer of thermal energy from the DUT to the thermal sensors.…”

Section: Physical Methodsmentioning

confidence: 99%

Two Decades of Condition Monitoring Methods for Power Devices

2021

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Condition monitoring (CM) of power semiconductor devices enhances converter reliability and customer service. Many studies have investigated the semiconductor devices failure modes, the sensor technologies, and the signal processing techniques to optimize the CM. Furthermore, the improvement of power devices’ CM thanks to the use of the Internet of Things and artificial intelligence technologies is rising in smart grids, transportation electrification, and so on. These technologies will be widespread in the future, where more and more smart techniques and smart sensors will enable a better estimation of the state of the health (SOH) of the devices. Considering the increasing use of power converters, CM is essential as the analysis of the data obtained from multiple sensors enables the prediction of the SOH, which, in turn, enables to properly schedule the maintenance, i.e., accounting for the trade-off between the maintenance cost and the cost and issues due to the device failure. From this perspective, this review paper summarizes past developments and recent advances of the various methods with the aim of describing the current state-of-the-art in CM research.

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“…These images are first digitized and a software program compares the two based on the pre-specified spatial resolution. The result of this comparison is a detailed temperature distribution map of the electronic part [10].…”

Section: Liquid Crystal Thermographymentioning

confidence: 99%

“…In addition, the highest spatial resolution achievable with LC thermography is limited by the type of TLC formulation and resolving capability of the optical system (camera and lenses). Unencapsulated TLC formulations [10] coupled with high performance microscope optics can provide sub-micron spatial resolution over reasonably sized fields of view.…”

Section: Limitation In Liquid Crystal Thermographymentioning

confidence: 99%

Electrothermal analysis of integrated circuits: a realization by infrared thermography

Farrokhi¹

2021

Preprint

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The International Technology Roadmap for Silicon (ITRS) predicted that by the year 2016, a high-performance chip could dissipate as much as 300 W/cm² of heat. Another more noticeable thermal issue in IC's is the uneven temperature distribution. Increased power dissipation and greater temperature variation highlight the need for electrothermal analysis of electronic components. The goal of this research is to develop an experimental infrared measurement technique for the thermal and electrothermal analysis of electronic circuits. The objective of the electrothermal analysis is to represent the behavior of the temperature dependent characteristics of electronic device in near real work condition. An infrared (IR) thermography setup to perform the temperature distribution analysis and power dissipation measurement of the device under test is proposed in this reasearch. The system is based on a transparent oil heatsink which captures the thermal profile and run-time power dissipation from the device under test with a very fine degree of granularity. The proposed setup is used to perform the thermal analysis and power measurement of an Intel Dual Core E2180 processor. The power dissipation of the processor is obtained by calculating and measuring the heat transfer coefficient of the oil heatsink. Moreover, the power consumption of the processor is measured by isolating the current used by the CPU at run time. A three-dimensional fininte element thermal model is developed to simulate the thermal properties of the processor. The results obtained using this simulation is compared to the experimental results from IR thermography. A methodology to perform electrothermal analysis on integrated circuits is introduced. This method is based on coupling a standard electrical simulator, which is often used in the design process, and IR thermography system through an efficient interface program. The proposed method is capable of updating the temperature dependent parameters of device in near real time. The proposed method is applied to perform electrothermal analysis of a power MOSFET to measure the temperature distribution and the device performance. The DC characteristics of the device are investigated. The obtained results indicated that the operating point, I-V characteristics and power dissipation of the MOSFET vary significantly with temperature.

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The use of thermochromic liquid crystals in research applications, thermal mapping and non-destructive testing

Cited by 15 publications

References 33 publications

Transient liquid crystal thermometry of microfabricated PCR vessel arrays

Transient liquid crystal thermometry of microfabricated PCR vessel arrays

Two Decades of Condition Monitoring Methods for Power Devices

Electrothermal analysis of integrated circuits: a realization by infrared thermography

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