Dual responsiveness of microgels induced by single light stimulus

Marek Bekir, Joachim Jelken, Se-Hyeong Jung, Andrij Pich, Claudia Pacholski, Alexey Kopyshev, Svetlana Santer*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


We report on the multiple response of microgels triggered by a single optical stimulus. Under irradiation, the volume of the microgels is reversibly switched by more than 20 times. The irradiation initiates two different processes: photo-isomerization of the photo-sensitive surfactant, which forms a complex with the anionic microgel, rendering it photo-responsive; and local heating due to a thermo-plasmonic effect within the structured gold layer on which the microgel is deposited. The photo-responsivity is related to the reversible accommodation/release of the photo-sensitive surfactant depending on its photo-isomerization state, while the thermo-sensitivity is intrinsically built in. We show that under exposure to green light, the thermo-plasmonic effect generates a local hot spot in the gold layer, resulting in the shrinkage of the microgel. This process competes with the simultaneous photo-induced swelling. Depending on the position of the laser spot, the spatiotemporal control of reversible particle shrinking/swelling with a predefined extent on a per-second base can be implemented.

Original languageEnglish
Article number091603
Number of pages6
JournalApplied Physics Letters
Issue number9
Publication statusPublished - 1 Mar 2021

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