Abstract
As up to 2014, there were about 123,800 patients in the U.S. waiting for a life saving organ transplant. Organ regeneration is a pressing issue as the waiting list of organ transplant is getting longer and longer year by year. To achieve the ultimate goal, the regeneration of organs, the lack of blood vessel in the regeneration of multi-layered is needed to be solved. In this work, a novel fabrication method, laser ablation, is developed for the fabrication of biodegradable microfluidic devices for the regeneration of vascularized tissue. Mircorfluidic devices with branched micro-size channels have been applied in detectors, sensors, and analytical separation. To crate biocompatible and biodegradable micorfluidic systems, one biocompatible polymer, poly(dimethylsiloxane) (PDMS), and two biodegradable polymers, poly(glycerol sebacate) (PGS) and poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate)s (APS), were synthesized for the fabrication of branched microfluidic systems using laser ablation. These branched microfluidic systems aim to mimic complex microvascular systems to provide nutrient and oxygen for organs such as kidney and liver regeneration. The biodegradable polymers, PGS and APS, with controllable stiffness and degradation rate are able to mimic microvascular systems in vivo, while degrading slowly during new tissue regeneration. Laser ablation is a rather simple fabrication method that can be easily controlled and is a safe process compared to conventional microfluidic system fabrication methods such as lithography and soft lithography. The channels depth can be controlled precisely and are high flexibility in the design of fabrication patterns by utilizing laser ablation. There are several fabrication parameters that require to be analyzed, including fluence (energy per unit area), beam size of laser pulse, beam velocity, beam firing frequency, and numbers of repeated ablation. In this study, the fluence was chosen as 6 J/cm^2 and the beam size of laser pulse was set as 150 μm. A few other parameters that can affect the fabrication of microfluidic devices are beam velocity, beam firing frequency, and numbers of repeated ablation. These parameters were thoroughly investigated, and are successfully applied in the fabrication of multiple devices. This study presents a revolutionary micropatterning methodology that enables the fabrication of a 3D microvascular system through a bottom-up process, and is expected to present new options for the field of tissue engineering.