The vast majority of microfluidic systems are molded in poly(dimethylsiloxane) (PDMS) by soft lithography due to the favorable properties of PDMS: biocompatible, elastomeric, transparent, gas-permeable, inexpensive, and copyright-free. However, PDMS molding involves tedious manual labor, which makes PDMS devices prone to assembly failures and difficult to disseminate to research and clinical settings. Furthermore, the fabrication procedures limit the 3D complexity of the devices to layered designs. Stereolithography (SL), a form of 3D-printing, has recently attracted attention as a way to customize the fabrication of biomedical devices due to its automated, assembly-free 3D fabrication, rapidly decreasing costs, and fast-improving resolution and throughput. However, existing SL resins are not biocompatible and patterning transparent resins at high resolution remains difficult. Here we report procedures for the preparation and patterning of a transparent resin based on low-MW poly(ethylene glycol) diacrylate (MW 250) (PEG-DA-250). The 3D-printed devices are highly transparent and cells can be cultured on PEG-DA-250 prints for several days. This biocompatible SL resin and printing process solves some of the main drawbacks of 3D-printed microfluidic devices: biocompatibility and transparency. In addition, it should also enable the production of non-microfluidic biomedical devices.

The Ilios 3D-Printer is on loan from 3D-Skema, Inc. A. U. is a recipient of a “La Caixa” fellowship from Catalonia and an European Molecular Biology Organization (EMBO) short-term fellowship. C. P. is a recipient of a “Consejo Nacional de Ciencia y Tecnología” (CONACYT) Mexican fellowship. F. P. is supported by the Spanish Ministry of Economy and Competitiveness (BFU2015-64437-P and FEDER), the Catalan Government (2014 SGR 599) and an ERC Advanced Grant Number 294294 from the European Union seventh framework program (SYNCOM). F. P. is supported by Fundación Botín, by Banco Santander through its Santander Universities Global Division and recipient of an ICREA Acadèmia (Generalitat de Catalunya). For the cell culture data and cell microscopy, we acknowledge partial support from the National Institutes of Health, grant number 1R01NS064387-01A2