Fabrication and testing of a droplet-based microfluidic neural implant

Neuroscientists have used fine gauge electrodes to record and stimulate the brain for decades. The main problem is the majority of neurological disorders involve problems with the chemical neurotransmitters, not electrical or electrochemical signal transduction. Due to this, a localised method needs to be developed to treat neurochemical disorders. This project investigates the fabrication of microfluidic device to be a chemical analogue to deep brain stimulation. We propose a modification to conventional droplet microfluidics that may enable water-based drug delivery and fluid sampling from the end of a microfabricated needle. The device will consist of a T-junction to generate water-in-oil droplets, a descending channel, a u-bend and a return channel. At the u-bend, the tip of the needle, a hydrophilic membrane will form the lid. Under positive/negative fluid pressure, droplets may be expelled/extracted through the membrane.This thesis describes how the microfluidic needle was fabricated using hot embossing, which involves pressing a PDMS mould (fabricated from a PMMA master mould) into a COC substrate. This microfluidic needle was tested using the Maesowregistered system to see if the channel is capable in producing water droplets in a continuous oil flow using a T-junction channel configuration. Bonding methods for bonding two COC substrates together, and a membrane to a COC lid were found in order to bond a COC lid to the embossed microfluidic channel.