Research on a novel temperature indicating device based on Bragg reflection waveguide of planar texture cholesteric liquid crystal layer

Abstract

In this paper, a temperature indicating device with double-layer planar texture cholesteric liquid crystal (PTCLC) is designed, which has great advantages over temperature card. It works based on the temperature dependence of the cholesteric liquid crystal helical pitch and the Bragg Reflection of PTCLC. A white light source is placed on one side of the waveguide element of the temperature indicating device, and only light of a particular wavelength can form guided wave due to the Bragg Reflection. The feasibility of the temperature indicating device was verified by measuring the Bragg reflectance spectrum and chromaticity coordinates at different temperatures.

Keywords:

• Bragg reflection waveguide
• cholesteric liquid crystal
• temperature indicating device
• temperature sensor

Authors’ contributions

All the authors were involved in the preparation of the manuscript. All the authors have read and approved the final manuscript

Disclosure statement

The authors declared that they have no conflicts of interest to this work.

Additional information

Funding

This research is supported by Innovation Method Fund of China (2020IM020600, 2018IM040300), Research Projects of Undergraduate Education and Teaching Reform in Hebei University of Technology (201903006), Higher Education Teaching Research Program of Hebei Society of Higher Education and the Natural Science Foundation (51805142).