Transparent and flexible structurally colored biological nanofiber films for visual gas detection

doi:10.1016/j.matt.2022.05.043

Matter

Volume 5, Issue 9, 7 September 2022, Pages 2813-2828

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Highlights

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Construct structurally colored film using sustainable biological nanofibers
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Multiple advantages are integrated into the one
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Achieve ultrafast color response to environment stimuli of less than 1 s
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Realize visual gas concentration detection simply upon blowing

Progress and potential

Stimuli-responsive films are attracting wide attention in the sensing field due to their ability to respond to temperature, moisture, and pH. However, realizing a low-cost and rapid preparation of structural-color responsive film with self-supported structure still remains a challenge. In this work, a structural-color film is developed simply by filtration of hydrophilic wood-derived nanocellulose on a hydrophobic porous membrane. The resultant film integrates multiple advantages into itself, including being ultrathin, iridescent, transparent, tailorable, flexible, foldable, and able to respond to various environment stimuli by changing color. Benefitting from its intrinsic structures and functions, the film is successfully used as portable testing paper for visual gas detection.

Summary

Structurally colored films hold promise as cheap platforms for use in visual detection. However, achieving accurate stimuli-responsive functions that can be distinguished by the naked eye in a single thin, robust, and practically useful material remains a challenge. Herein, we demonstrate flexible and self-standing structurally colored films fabricated by filtrating sustainable hydrophilic nanofibrillated cellulose through a porous hydrophobic membrane, followed by natural drying. 480–644 nm thick and composed of densely packed, high-aspect-ratio nanofibers entangled in web-like structures, the films are transparent, tailorable into a variety of shapes, and easily foldable. They exhibit iridescence owing to thin-film interference and reversibly change color in seconds when exposed to various moist gases and liquids. We validate the visual gas-detection capabilities of the films by measuring the ethanol concentration in the breath of an inebriated participant and envisage that these materials will find use in automated and broad-spectrum gas-detection devices.

Graphical abstract

Keywords

structural color

nanofibrillated cellulose

film

iridescence

interference

Material advancement progression

MAP4: Demonstrate

Data and code availability

The data that support the plots of this study may be reasonably requested from the corresponding authors.

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