Thermotropic Liquid Crystals for Temperature Mapping

Abstract

Wound management in Space is an important factor to be considered in future Human Space Exploration. It demands the development of reliable wound monitoring systems that will facilitate the assessment and proper care of wounds in isolated environments, such as Space. One possible system could be developed using liquid crystal films, which have been a promising solution for real-time in-situ temperature monitoring in healthcare, but they are not yet implemented in clinical practice. To progress in the latter, the goal of this study is twofold. First, it provides a full characterization of a sensing element composed of thermotropic liquid crystals arrays embedded between two elastomer layers, and second, it discusses how such a system compares against non-local infrared measurements. The sensing element evaluated here has an operating temperature range of 34–38°C, and a quick response time of approximately 0.25 s. The temperature distribution of surfaces obtained using this system was compared to the one obtained using the infrared thermography, a technique commonly used to measure temperature distributions at the wound site. This comparison was done on a mimicked wound, and results indicate that the proposed sensing element can reproduce the temperature distributions, similar to the ones obtained using infrared imaging. Although there is a long way to go before implementing the liquid crystal sensing element into clinical practice, the results of this work demonstrate that such sensors can be suitable for future wound monitoring systems.

Temperature-Responsive Structurally Colored Fibers via Blend Electrospinning

“…Notably, the first color observed for the PCL/LC mats was purple compared to blue typically reported for the LC alone. 15,17,39 The visual observation (Figure 6A) was confirmed using a chromaticity diagram in International Commission of Illumination (CIE) 1931 color space 44,72 to demonstrate the range of colors observed during cooling (Figure 6C). Representative images from the video analysis of PCL/LC-3 were analyzed and compared to representative images of LC-3 (Figure S14).…”

“…Electrospinning temperature-responsive fibers could enable innovative face mask design, e.g., color change indicator of respirator fit or fever based on changes in temperature. Thermotropic liquid crystals (LCs) have been widely used in temperature indicators based on visual observation of their structural color. , Their temperature-dependent structural color arises from the molecular, helical structure of the cholesteric phase with a temperature-dependent pitch length. , When the pitch length is on the order of the wavelength of visible light, the LC phase reflects visible light due to Bragg reflection , leading to strong iridescent color . Changes in temperature result in twisting and untwisting of the helical structure resulting in reversible changes in the pitch length and thus the reflected color.…”

“…Thermotropic liquid crystals (LCs) have been widely used in temperature indicators based on visual observation of their structural color. 15,16 Their temperature-dependent structural color arises from the molecular, helical structure of the cholesteric phase with a temperature-dependent pitch length. 15,16 When the pitch length is on the order of the wavelength of visible light, the LC phase reflects visible light due to Bragg reflection 17,18 leading to strong iridescent color.…”

Investigation of Soft Matter Nanomechanics by Atomic Force Microscopy and Optical Tweezers: A Comprehensive Review

“…Liquid crystals show excellent electro-optical, reflectance, anisotropic polarizability and low energy consumption qualities. Liquid crystals are widely used as detergent [ 26 ], for the realization of displays [ 27 ], thermal detection [ 28 ] and clinical diagnosis sensors [ 29 ]. Finally, cells and bacteria are the fundamental anatomical unit of all living organisms and prokaryotic microorganisms that do not bear defined nuclei and generally internal membranous organelles, respectively.…”

“…Liquid crystals show excellent electro-optical, reflectance, anisotropic polarizability and low energy consumption qualities. Liquid crystals are widely used as detergent [ 26 ], for the realization of displays [ 27 ], thermal detection [ 28 ] and clinical diagnosis sensors [ 29 ].…”