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Recent advances in embedded 3D bioprinting have significantly improved the resolution of individual filaments to below 100 µm; however, printing with such small filaments requires accurate extrusion of nanoliter volumes of bioink. Commercially available bioprinters and extruders are expensive and most utilize pneumatic control, which limits the minimum extrusion volume and prevents retraction (pulling bioink back into the reservoir), which is essential to printing high resolution features and complex internal geometry. Here we present a new generation of our open-source syringe pump designed for extrusion-based 3D bioprinting of soft materials: the Replistruder 4. The Replistruder 4 takes advantage of the geometry customizability and ease of 3D plastic printing while improving performance by integrating mass produced high-precision linear motion components. Simultaneously this new syringe pump remains compact and lightweight enough for several to be utilized on a 3D bioprinter for multimaterial bioprinting. To facilitate multiple use cases the Replistruder 4 is compatible with a range of syringes including disposable BD and Hamilton gastight syringes. In addition, we describe the process of designing clamps for other syringes. We demonstrate the performance of a Replistruder 4 with a 2.5 mL Hamilton gastight syringe by printing collagen type I constructs with individual filaments comprising 3.35 nL and patent channels down to 300 µm in width. With smaller volume Hamilton gastight syringes this performance can be further improved. Thus, the Replistruder 4 provides an open-source solution to print soft materials at the resolution limits of current embedded bioprinting platforms.

Mechanical characterization and tensile testing of biological samples is important when determining the material properties of a tissue; however, performing tensile testing and tissue stretching while monitoring cellular changes via fluorescence microscopy is often challenging. Additionally, commercially available cell/tissue stretchers are often expensive, hard to customize, and limited in their fluorescence imaging compatibility. We have developed a 3D printed Open source Biaxial Stretcher (OBS) to be a low-cost stage top mountable biaxial stretching system for use with live cell fluorescence microscopy in both upright and inverted microscope configurations. Our OBS takes advantage of readily available open source desktop 3D printer hardware and software to deliver a fully motorized high precision (10 ± 0.5 µm movement accuracy) low cost biaxial stretching device capable of 4.5 cm of XY travel with a touch screen control panel, and an integrated heated platform with sample bath to maintain cell and tissue viability. Further, we designed a series of tissue mounts and clamps to accommodate varying samples from synthetic materials to biological tissue. By creating a low-profile design, we can directly mount the stretcher onto a microscope stage, and through coordinated biaxial stretching we maintain a constant field of view facilitating real-time sample tracking and time-lapse fluorescence imaging.