Fabrication of flexible microelectrode arrays integrated with microfluidic channels for stable neural interfaces

• We proposed a new simple and low-cost method to integrated microchannels to thin film polyimide microelectrode arrays for drugs delivery.
• We investigated the reliability of our device through experiment.
• We studied the release process from aspects of experiment and simulation and compared the release results between simulation and experiment.
• The experiment result indicates that the device can meet the requirements of long-term release and sufficient drug loading.

To achieve long-term effectiveness of implanted neural prostheses, we developed a simple and low-cost fabrication process for flexible neural microelectrodes integrated with microfluidic channels for simultaneous drug delivery and multi-channel stimulation. In this process, a conventional thin-film electrode fabrication procedure is combined with poly(dimethylsiloxane) molding and a bonding technique. Compared with the current fabrication method, this process significantly reduces the cost and time needed for fabrication. The microelectrodes were characterized by optical microscopy, impedance measurements and diffusion tests. A numerical simulation was also performed to demonstrate the fluid dynamics of drug release through the microchannels and evaluate the device's performance in terms of its delivery rate and efficiency. The results show that the drug release rate is about 20% of the total amount per day in the first two days and about 4% of the total amount per day in each of the next 10 days. The release process can last more than 2 weeks. The result meets the requirement for long-term release and sufficient drug loading.