Stereolithography (SLA) is a widely used technique for the fabrication of prototypes and small series products. The main advantage of SLA and related solid freeform fabrication (SFF) techniques is their capability to fabricate parts with complex shapes with high resolution. Although the spectrum of available materials has been widened in recent years, there is still a lack of materials which can be processed with SLA on a routine basis. In this work, a micro-SLA (μSLA) system is presented which can shape a number of different photopolymers with resolutions down to 5 μ mi n thexy-plane and 10 μ mi n thez-direction. The system is capable of processing various specifically tailored photopolymers which are based on acrylate chemistry. The materials processed for this work range from hybrid sol-gel materials (ORMOCER) to photo-crosslinked elastomers and hydrogels. The elastic moduli of these materials can be tuned over several orders of magnitude and range from 0.1 MPa to 8000 MPa. The reactivity of these monomers is sufficient for achieving writing speeds up to 500 mm s−1 which is comparable to commercial SLA resins. Various test structures are presented which show the suitability of the process for fabricating parts required for applications in micro-mechanical systems as well as for applications in biomedical engineering. Using the presented system, internal channels with a diameter of 50 μm and a length of 1500 μm could be fabricated. It was also possible to manufacture a micro-mechanical system consisting of a fixed axe and a free spinning turbine wheel. (Some figures in this article are in colour only in the electronic version)

A highly efficient waterborne bis(acyl)phosphane oxide photoinitiator (PEG-BAPO) was conveniently synthesized for 3D printing of hydrogels under blue light irradiation.

A photolabile ruthenium‐based complex, [Ru(bpy)₂(4AMP)₂](PF₆)₂, (4AMP=4‐(aminomethyl)pyridine) is incorporated into polyurea organo‐ and hydrogels via the reactive amine moieties on the photocleavable 4AMP ligands. While showing long‐term stability in the dark, cleavage of the pyridine–ruthenium bond upon irradiation with visible or near‐infrared irradiation (in a two‐photon process) leads to rapid de‐gelation of the supramolecular gels, thus enabling spatiotemporal micropatterning by photomasking or pulsed NIR‐laser irradiation