Electrodes Go Live

In the seven years we’ve been publishing Neurotech Business Report, we’ve seen our fair share of technological innovations and promising scientific developments. But rarely have we seen the type of far-reaching and transformative progress in neurotechnology represented by new developments in bioactive, conducting polymer electrodes. As we report in our article on page 1 of this issue, research in this area has moved out of the laboratory and into the commercial marketplace.

Much of the key research has been conducted by David Martin’s group at the University of Michigan. We’ve been following Martin’s presentations at the Neural Prosthesis Workshop since 2001. While there are several other institutions performing excellent research in electrode biomaterials, including University of Utah, Georgia Tech, and UT Southwestern [see article p8], the Michigan team deserves particular credit for evangelizing new interface technology.
Part of the reason for our enthusiasm for this new technology is that it addresses several problems with current-generation neural interfaces.

Almost all implanted neurostimulation devices on the market today are based on metal electrodes that come into contact with neural tissue. The better the contact, the more useful the device. For example, a DBS lead that is inserted even 1 or 2 millimeters away from the desired target will likely produce less effective therapy than a precisely placed lead.

Metal electrodes are stiffer than surrounding brain tissue, and are prone to all the mechanical impacts the human body is exposed to. Implanted electrodes frequently produce inflammation and sheaths of glial tissue surrounding the foreign object, which can not only lead to tissue injury but also reduce the electrical effectiveness of the device. The increased biocompatibility and electrical signal transduction properties of conducting polymer electrodes address each of these issues and promise a new generation of implanted electrodes that will benefit patients and clinicians.

But the larger reason we’re excited about this technology relates to the nature of neural communication itself. Martin’s team has grown networks of PEDOT electrodes that are intimately intertwined with neural cells. They have also produced hybrid electrodes that incorporate both conducting polymers and live neural cells. The goal is to create a matrix that actually attracts neural cells to the biomimetic template. Clearly, the boundary between what is nervous system and what is external device is blurring.

A neural environment where implanted device and neural cells coexist peacefully—even migrate and evolve together over time—is not only safer and more effective for the end user. It is also the ultimate manifestation of the melding of man and machine.

James Cavuoto
Editor and Publisher