Surface Wrinkling of Plasma-Exposed PDMS is Caused by Water Vapor Sorption: An Optical Environmental Sensor

Published

June 18, 2025

Author(s)

Jack Douglas, Zain Ahmad, Tyagi Tyagi, Shuning Xiang, Jerry Heng, Pedro Patrício, Paulo Teixeira, Christopher Stafford, Joao T. Cabral

Abstract

Wrinkling of polydimethylsiloxane (PDMS) has unlocked a plethora of technological applications, from tunable surface wetting to photonic response. Surface undulations with prescribed wavelength and amplitude are excited by in-plane mechanical compression of bilayers comprising a thin, stiff outer skin on a soft elastomer or gel. Plasma oxidation has become ubiquitous for creating such thin (≈10 nm) glassy interfacial layers. Spontaneous wrinkling can occur even in the absence of external mechanical strain fields, which has been rationalized in terms of a thermally-induced strain that accompanies the expansion-contraction cycle of such laminate films. Here, we show that exposure to water vapour is, instead, responsible for surface wrinkling, due to the swelling the oxidised skin layer. This interpretation of surface wrinkling provides a rationale for the apparent experimental variability of the wrinkling process. We verify this hypothesis experimentally by observing and modelling the spatiotemporal evolution of the reversible wrinkling process under a range of controlled environmental conditions. From a practical standpoint, we find that this effect provides for a facile approach for humidity sensing, through structural color changes arising from the diffractive wrinkled skin.

Citation

Advanced Functional Materials

Volume

35

Issue

47

Pub Type

Journals

Download Paper

https://doi.org/10.1002/adfm.202509167

Local Download

Keywords

wrinkling, PDMS, plasma, relative humidity, structural color, switch

Citation

Douglas, J. , Ahmad, Z. , Tyagi, T. , Xiang, S. , Heng, J. , Patrício, P. , Teixeira, P. , Stafford, C. and Cabral, J. (2025), Surface Wrinkling of Plasma-Exposed PDMS is Caused by Water Vapor Sorption: An Optical Environmental Sensor, Advanced Functional Materials, [online], https://doi.org/10.1002/adfm.202509167, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959237 (Accessed February 17, 2026)