| Neural microelectrodes are an important and essential component in neuroscience and neural prosthetics. Single or arrays of microelectrodes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. They are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer's, and dementia. They are used to stimulate sub-cortical structures in patients with Parkinson's disease. At the same time, they assist paralyzed patients by allowing them to operate computers or robots using their neural activity. In neural prosthetic systems, implanted microelectrodes record the electrical potentials generated by specific thoughts and relay the signals to algorithms/robots trained to interpret these thoughts and perform specific actions.;Compared with the traditional silicon neural probes, our microfabricated multimodal neural probes (being reinforced) are much longer and stronger microelectrodes (10.5 mm long, able to penetrate the pia layer in the brain) with lower stress and better penetration ability. These multimodal probes provide additional signals which will increase the information yield when compared to standard probes that record just electro-potentials. At the same time, our new probe arrays are shown to improve biocompatibility (with their surface textured with porous silicon).;In the future, based on the principles described here, monitoring of many other biomarkers including glucose, pH, and neurotransmitters is possible. This can be achieved by integrating various optical biochemical sensors that are responsive to these biomarkers with neural electrodes.;The work in this thesis is focused on developing novel elongated multi-site multimodal neural electrodes that can record electrical signals and brain tissue oxygenation. These electrodes reach depths greater than 10mm in the brain. The majority of the research efforts have concentrated on the fabrication and integration of optical biochemical sensors with neural microelectrodes. The neural biomarker sensors are made using sol-gel derived xerogel thin films that encapsulate specific analyte responsive luminophores in their nanostructured pores. The desired neural biomarker is brain tissue oxygenation. These contributions have led to the first prototype demonstration of a hybrid silicon neural probe integrating a fiber optic coated with oxygen (O2)-responsive xerogel inside the neural microelectrodes. The recording of brain tissue oxygenation along with electrical activity could help the development of intelligent neural prosthesis/brain machine interfaces as well as aid in providing new foresights into complex brain diseases and disorders. |
