Silicon Micro-Needles with Flexible Interconnections

A flexible polyimide-based interconnect scheme was developed to realize isolated needle-like microelectrodes. A simple fabrication approach allows the integration of micromachined silicon needles with a larger silicon base designed to carry elements such as amplifiers, battery or memory. The interconnecting scheme uses two polyimide layers to sandwich a metallic layer. The metal layer forms the electrical connection between the silicon base and the micro-electrodes, while the polyimide layers provide flexible insulation. The current design allows convenient handling of the device during implantation and minimal mechanical load on the implanted region. The device can conform to the surface of neural tissue and allows convenient interfacing with rugged and dynamic tissues. Prototype devices were tested for usability and animalcompatibility. The devices were implanted in sea slugs (Tritonia diomedea) and extracellular signals were acquired. Tritonia diomedea show full recovery from surgery and implantation, and survive up to a minimum of fourteen days with the ability to perform normal behaviors.