Sticker molds and stencils for low-cost rapid-fabrication of polymer and textile-based biomedical devices

SU-8 molds are used to prototype polydimethylsiloxane (PDMS) devices but require specialized skill, time, and costly photolithographic equipment to fabricate. Low-cost polymer alternatives such as laser-ablated polymethylmethacrylate (PMMA) molds have been explored, but are limited by the surface roughness of the ablated PMMA which transfers to molded PDMS devices. In addition, screens and stencils are widely used as ink masks for direct on-textile fabrication, but may suffer from seepage underneath their edges, resulting in lower pattern resolution. In this work we present “sticker molds” for ultra-rapid prototyping. For fabrication of PDMS devices, these molds are comprised of a glass substrate with layers of Uline Industrial Tape S-423 patterned by laser ablation. We examine the geometry and surface roughness of these molds and the resultant PDMS devices using microscopy and profilometry. Channels dimensions as small as 100 μm wide and 50 μm deep are achieved, with a W-shaped kerf. These molds have low material cost (< 10 cents Canadian per mold), require under 10 minutes to fabricate, and have low surface roughness, resulting in smooth PDMS devices that readily bond. For devices directly printed on textiles, “sticker stencils” developed from simple sticky paper can also be patterned using laser ablation, and adhered to the textile or existing ink patterns. The low barrier to entry makes sticker molds and stencils ideal for rapid proof-of-concept work where designs are frequently changing, or a classroom setting. Furthermore, we employ sticker stencils for development of electronic and microfluidic structures directly on textiles for wearable biomedical systems.