Rapid photothermal actuation of light-addressable, arrayed hydrogel columns in a macroporous silicon membrane

This paper presents rapid photothermal actuation of light-addressable, arrayed hydrogel columns in a macroporous silicon membrane. Au nanorods are incorporated into thermo-responsive p-NIPAAm hydrogel to utilize surface plasmon-induced local heating by near-infrared light. By measuring optical transmission through the fabricated membrane structure with Au nanorod embedded hydrogel, we have demonstrated that photothermal actuation of hydrogel can be done in two-dimensional, pixel-like configuration with high spatial and temporal resolutions. Benefiting from the hydrogel volume confinement within micron-sized pores, we have achieved sub-second response time of hydrogel photothermal actuation and its repeatable photothermal actuation on highly localized illuminated area. Considering that each hydrogel column is confined within each pore and different wavelength of light can be used to induce photothermal actuation of hydrogel's deswelling characteristics by modifying physical dimensions of Au nanorods, it has a potential for optically-addressable, multiplexed drug release systems with rapid response time.