A study of thermal crosslinking hydrogel with coaxial needle for manufacturing tubular shape structure

Primary author: Ilhan Yu
Co-author(s): Luiz Longo
Faculty sponsor: Chen, Roland

Primary college/unit: Voiland College of Engineering and Architecture
Campus: Pullman


Extrusion using a coaxial needle to create tubular shapes has become a popular method in tissue engineering and drug delivery. Chemical crosslinking hydrogels were the most popular materials used to manufacture tubular shapes with coaxial needles, but because of fast gelation times, non-uniform gelation, and low strength and toughness have been pointed out as drawbacks. Thus, in this study, we investigated the feasibility of using a thermal crosslinking hydrogel with coaxial needle to get the tubular shape. Gellan Gum (GG), a thermal crosslinking material, was used and extruded via the outer needle. Phosphate-buffered saline (PBS) was extruded through the inner needle. First, we analyzed the delay and response time of the system due to heat exchange of the two fluids computationally. Second, we determined the hydrogel extrusion condition and its influence on the structural geometry of shapes structure both computationally and experimentally. Various flow rates of the inner needle and outer needle was tested, and the resulting wall thickness of the structure was measured. Results show that there is a delay of transition for thermal hydrogels due to the heat exchange between two fluids. The response time of system when the flow rate of PBS changes from steady state and how long does it takes to become steady state. In the second part of the experiment, we observed that it is possible to control the wall thickness of tubular shape by changing inner fluid with certain boundary.