Bioinspired Hydrogel Interferometer for Adaptive Coloration and Chemical Sensing

Abstract

Living organisms ubiquitously display colors that adapt to environmental changes, relying on the soft layer of cells or proteins. Adoption of soft materials into an artificial adaptive color system has promoted the development of material systems for environmental and health monitoring, anti-counterfeiting, and stealth technologies. Here, a hydrogel interferometer based on a single hydrogel thin film covalently bonded to a reflective substrate is reported as a simple and universal adaptive color platform. Similar to the cell or protein soft layer of color-changing animals, the soft hydrogel layer rapidly changes its thickness in response to external stimuli, resulting in instant color change. Such interference colors provide a visual and quantifiable means of revealing rich environmental metrics. Computational model is established and captures the key features of hydrogel stimuli-responsive swelling, which elucidates the mechanism and design principle for the broad-based platform. The single material-based platform has advantages of remarkable color uniformity, fast response, high robustness, and facile fabrication. Its versatility is demonstrated by diverse applications: a volatile-vapor sensor with highly accurate quantitative detection, a colorimetric sensor array for multianalyte recognition, breath-controlled information encryption, and a colorimetric humidity indicator. Portable and easy-to-use sensing systems are demonstrated with smartphone-based colorimetric analysis.

Graphene Oxide as an Optical Biosensing Platform: A Progress Report

“…A 2.9-fold enhancement was discussed in this biosensing approach studied by Stebunov et al, [98] see Figure 5B. [20,[111][112][113] iv) A charge transferring phenomenon that improves SERS performance. This research team engineered an SPR substrate based on a GO-coated Au surface for the screening of a cardiac biomarker (galectin-3), reaching a clinically relevant concentration range.…”

“…In fact, GO optical transparency has been found to decrease with GO thickness, [4,7] see Figure 1A. [20] It is well known that GO can be exploited as an outstanding quencher of photoluminescence. [8][9][10][11][12] Aside from this, monolayer GO optical transmittance has been reported to be modulated up to 24.8% by using an external electric field, [13] which has been associated with the electric-field-induced changes of electronic density of localized states and may enable new biosensing strategies based on electrochromic or optoelectronic principles/mechanisms.…”

Hydrogels for Medical and Environmental Applications

“…Elevated levels of major pollutants like CO 2 , CO, O 3 , NH 3 , SO x , NO x , etc., cause severe threats to human health and the environment, directly or indirectly . Apart from gases, sensing of chemicals like aldehydes, pollutants, food color, moisture, etc., will be crucial, especially in applications pertaining to food science, health care, etc . This makes it important to monitor the levels of these substances in our environment and take measures to keep them below permissible limits.…”

Bioinspired Healable Mechanochromic Function from Fluorescent Polyurethane Composite Film

“…Security encryption for information protection can be achieved by using composite materials under external stimuli . High‐level security encryption is required to protect information as the prevalence of informatization and digitization.…”