| Description |
Implantable devices have the potential to solve current challenges in both physiological monitoring and drug delivery by introducing in situ measurement and treatment. In this dissertation, two types of implantable devices will be discussed. First, implantable devices for monitoring intraocular pressure (IOP) will be addressed. Second, implantable devices made of both nonbiodegradable and biodegradable materials for bridging a peripheral nerve gap by in situ drug delivery will be discussed. Elevated IOP serves as a major factor that leads to glaucoma, a permanent vision loss disease, and a real-time monitoring implantable IOP sensor with polydimethylsiloxane membrane that was developed. This IOP sensor can be either implanted in the lens capsular bag after cataract surgery or sandwiched between the sclera and the conjunctiva; the latter being more favorable due to easy signal retrieval. For this approach, batch testing data showed a sensitivity of 0.67 mm/mmHg with the range of the device closely matching that expected for glaucoma patients. Another medical challenge addressed in this dissertation is that peripheral nerve gaps longer than 10mm require special bridging techniques to repair. Autologous nerve grafts are the gold standard to repair peripheral nerve gaps; however, it possesses donor site deficit. Hence, a drug delivery device consisting of a nerve conduit for guided axon growth is proposed, fabricated and verified in this dissertation. Both nonbiodegradable materials and biodegradable materials were used to make the device that can deliver vascular growth factor, nerve growth factor (NGF), bovine serum albumin and polysaccharide. Furthermore, a bioactivity test verified that the NGF released from the device was still bioactive in promoting axonal outgrowth on chick dorsal root ganglia explants. Two 3-week pilot animal studies in mice and rats also showed that the device is biocompatible with no noticeable inflammatory response. For the release kinetics, the device using diffusion through holes instead of a filter membrane had better consistency in release kinetics. Two mathematical models were also developed to identify the optimal design of the nerve conduit and the model was verified by an in vitro release study. Thus, the model will be used to help determine future nerve conduit designs. |
