Development of a Light Source Integrated Flexible Microelectrode Array for Neuronal Applications

Abstract

Neuromodulation is a clinical therapeutic tool to modify the neuronal activities in order to address the disorders associated with the nervous system. The most recent development in neuromodulation tools is optogenetics which combines genetic engineering with optics. This is used for stimulation as well as inhibition of neuronal cell activities. Optogenetics is designed to observe and control the function of genetically targeted groups of cells with light. Such neuromodulation technique is often the case with respect to intact animals studies. The purpose of the thesis work is to design and develop a light delivery system called optrode for targeting the neuronal tissues. An optrode is an implantable electrode with light emitting structure on a single substrate. The main goal of the thesis work is to bond a light source to flexible substrate foil which embeds platinum electrodes to form optrode for brain implants. Such a system is characterized for placement on surface cortex of the brain. It can be visualized as an integration of implantable Electrocorticography electrodes with Light Emitting Diodes (LED).This is achieved by incorporating commercially available LED in an electrode grid structure. And the fabricated optrode is characterized for bio-compatibility. The work included characterization of the LED, integration to a flexible polymer substrate and to study light interaction with brain tissues. The work started by understanding the brain s environmental conditions under which the implant is to be done. Using statistical analysis like Failure Mode Effect Analysis and Pareto Analysis the operating conditions for an implanted device on surface cortex are determined. Based on the results thermal simulations newlinewere carried out to determine the nature of heat generated and methods to dissipate newlinethe heat while implanting an optrode. A flexible substrate with pads for bonding newlinedevices was developed. The conducting paths for the devices on the flexible substrate are 3D printed using Aerosol and Ultrasonic techniques