Direct Laser Writing Photonic Crystal Hydrogels with a Supramolecular Sacrificial Scaffold

Abstract Photonic crystal hydrogels (PCHs), with smart stimulus‐responsive abilities, have been widely exploited as colorimetric sensors for years. However, the current fabrication technologies are mostly applicable to produce PCHs with simple geometries at the sub‐millimeter scale, limiting the introduction of structural design into PCH sensors as well as the accompanied advanced applications. This paper reports the microfabrication of three‐dimensional (3D) PCHs with the help of supramolecular agarose PCH as a sacrificial scaffold by two‐photon lithography (TPL). The supramolecular PCHs, formulated with SiO₂ colloidal nanoparticles and agarose aqueous solutions, show bright structural color and are degradable upon short‐time dimethyl sulfoxide treatment. Leveraging the supramolecular PCH as a sacrificial scaffold, PCHs with precise 3D geometries can be fabricated in an economical and efficient way. This work demonstrates the application of such a strategy in the creation of structural‐designed PCH mechanical microsensors that have not been explored before.