Parylene-based implantable interfaces for biomedical applications

2018-05-09Implantable medical devices make possible the treatment of chronic conditions by providing continuous treatment at or near the affected area. BioMEMS technologies allow for the development of complex, smaller, and versatile implantable devices. However, reliable chronic performance in vivo has been limited by poor biocompatibility, mechanical mismatch to the soft biological tissue, inappropriate packaging, and lack of combined functionalities within a device (e.g. electrodes, drug delivery, sensors). Fortunately, these challenges can be overcome by utilizing Parylene C as an encapsulation or structural material. Parylene-based implantable devices hold promise due to high biocompatibility, flexibility, good water barrier properties, and compatibility with standard MEMS fabrication techniques. Presented in this work are two bioMEMS devices for clinical applications designed to achieve reliable chronic performance in vivo. ❧ Human drug therapies are initially evaluated in small animal models such as rodents; therefore, drug administration technologies for small laboratory animals are critically important for drug discovery and development. Chapter 2 presents an implantable micropump intended for evaluation and development of drug therapies in small laboratory animals for management of chronic conditions. A MEMS approach was implemented to allow miniature form factor and completely wireless operation of the micropump. The micropump’s ability to administer a tailored anti-cancer regimen under wireless operation was investigated under simulated in vivo conditions. ❧ The potential of peripheral nerve (PN) interfaces has been marred by the limited in vivo lifetime of current technology due to biological and non-biological failure modes. If PN interfaces functioned reliably under chronic conditions (in the range of multiple years), the promise of restoring sensory and motor control in amputees can be realized. Chapter 3 presents a novel Parylene-based peripheral nerve interface for restoring sensory and fine motor control in amputees. In an effort to improve the reliability of the current state-of-the art, we leveraged Parylene’s thin, flexible substrate and compatibility with batch microfabrication techniques with a unique drug delivery system to enhance implant-tissue integration in vivo and prolong chronic performance. The Parylene-based PN interface was designed, fabricated, and characterized. Finally, chapter 4 focuses on evaluating and improving the reliability of the Parylene-based PN interface for chronic in vivo implementation. The electrical, microfluidic, and mechanical functions of the LACE were tested and characterized under simulated and acute in vivo conditions to evaluate the interface potential for achieving successful chronic performance