Fig. S1.

Detailed illustration of the flow-focusing device used to assemble PNFs into microfibers. (A) The flow setup consists of syringe pumps, a flow-focusing channel, and a bath for the outlet of protein hydrogel fibers. Syringe pumps were used to control the flow rates of the core and sheath flows. The outlet of the channel was submerged into the bath solution. (B) The flow channel was milled in a 1-mm-thick stainless steel plate and sandwiched between two Plexiglas plates. Over the Plexiglas plates, two aluminum plates were placed on either side and screwed together to prevent leakage. All of the channels in the flow-focusing geometry were 1 mm in width.