Colorimetric Sensor Based on Hydroxypropyl Cellulose for Wide Temperature Sensing Range

Abstract

Recently, temperature monitoring with practical colorimetric sensors has been highlighted because they can directly visualize the temperature of surfaces without any power sources or electrical transducing systems. Accordingly, several colorimetric sensors that convert the temperature change into visible color alteration through various physical and chemical mechanisms have been proposed. However, the colorimetric temperature sensors that can be used at subzero temperatures and detect a wide range of temperatures have not been sufficiently explored. Here, we present a colorimetric sensory system that can detect and visualize a wide range of temperatures, even at a temperature below 0 °C. This system was developed with easily affordable materials via a simple fabrication method. The sensory system is mainly fabricated using hydroxypropyl cellulose (HPC) and ethylene glycol as the coolant. In this system, HPC can self-assemble into a temperature-responsive cholesteric liquid crystalline mesophase, and ethylene glycol can prevent the mesophase from freezing at low temperatures. The colorimetric sensory system can quantitatively visualize the temperature and show repeatability in the temperature change from −20 to 25 °C. This simple and reliable sensory system has great potential as a temperature-monitoring system for structures exposed to real environments.

Bioinspired Confined Assembly of Cellulosic Cholesteric Liquid Crystal Bubbles

“…Temperature sensitivity is an inherent property of HPC mesophase. Typically, at higher temperatures, the structural color of HPC CLCs red-shifts due to increase of p. [39][40][41] We reasoned that the as-prepared HPC microbubbles would retain this property since the ETPTA resin shell provided a stable and transparent shield. In addition, AM molecules can form hydrogen bonds with both HPC and water molecules (Figure 6A), which facilitates the self-assembly of HPC and does not impede the intrinsic temperature-responsiveness of HPC (Figure 6B).…”

Enzyme Mimetic Activity of Intercalated Pd–H Nanosheets for Bioanalysis

“…The results suggest that the sensor assay performed well and maintained a constant color transition in the temperature range of 0−35 °C (Figure S12). 61 Therefore, this sensor assay is expected to be used for a long time with a wide temperature range and without losing its temperature-sensing capability in different environments. To verify the practicability of the designed detection assay, actual samples were used for malathion detection.…”